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Fluke molbox RFM, Operation And Maintenance Manual

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3.  OPERATION 

 

Page 41 

© 1998-2007 DH Instruments, a Fluke Company 

When the TARE function is activated, molbox RFM’s internal valves operate to 
pneumatically connect together the two absolute transducers, and both legs of 
the microrange option differential transducer if present, at the molbloc operating 
pressure. The user can select whether this pressure is the upstream or 
downstream molbloc pressure so that the 

tare

 can be made at the pressure that 

will be held stable during operation (generally by a regulator or because it is 
open to atmosphere).  Activating the 

tare

 causes molbox RFM to record the 

current differential as the 

tare value

. The 

tare value

 will be used to correct all 

subsequent RPT readings. For the absolute transducers the 

tare value

 is the 

difference between the two transducer readings (hi - lo). The upstream RPT will 
be corrected by (- 

tare value

/2) and the downstream RPT will be corrected by (+ 

tare value

/2). For the microrange differential RPT, the 

tare value

 is the differential 

value read. The differential transducer will be corrected by subtracting the 

tare 

value

 from the current reading. 

 

1. 

High Isolation:   

Open 

2. 

Low Isolation: 

Closed  

3. Bypass: 

 

Open 

4. Mirorange 

Bypass: 

Open 

 

 

 

Figure 5.  

molbox RFM 

Internal Pneumatic Schematic – TARING, UPSTREAM molbloc-L OPERATION 



 OPERATION 

 

 

At a minimum, the TARE function should be executed whenever the operating 
pressure of the molbloc is changed significantly, at the beginning of each 
test or any time a significant zero error is observed.  For best results, it is 
possible to 

tare

 before every reading since taring can be executed while 

flowing.  Best results will be obtained if the TARE function is executed with a 
stable flow through the molbloc. 

To access the TARE function press 

[TARE]

, 

<1tare>

. 

The display is: 

Select tare pressure:

1upstream 2dnstream 

 

Selecting 

<1upstream>

 will 

tare

 the molbox RFM RPTs at the molbloc’s 

upstream pressure (see Figure 5).  Selecting 

<2dnstream>

 will 

tare

 the RPTs at 

the molbloc’s downstream pressure (Low isolation valve open, High isolation 
valve closed).  Select the position where the pressure will remain the most stable 
during molbloc operation. 

Summary of Contents for molbox RFM

Page 1: ... 1998 2007 DH Instruments a Fluke Company molbox RFM Ver 1 10 and Higher Reference Flow Monitor Operation and Maintenance Manual ...

Page 2: ...uments disclaims any responsibility or liability for any direct or indirect damages resulting from the use of the information in this manual or products described in it Mention of any product does not constitute an endorsement by DH Instruments of that product This manual was originally composed in English and was subsequently translated into other languages The fidelity of the translation cannot ...

Page 3: ...6 1 2 4 1 4 MOLBLOC L RANGES WITH HIGH PRESSURE CALIBRATIONS 7 1 2 4 1 5 MOLBLOC L DIMENSIONS 8 1 2 4 2 MOLBLOC S 9 1 2 4 2 1 MOLBLOC S RANGES 9 1 2 4 2 2 MOLBLOC S PRESSURE DEPENDENT CALIBRATION TYPES 11 1 2 4 2 3 MOLBLOC S DIMENSIONS 12 1 2 5 FRONT AND REAR PANELS 13 1 2 5 1 FRONT PANEL 13 1 2 5 2 REAR PANEL 14 2 INSTALLATION 15 2 1 UNPACKING AND INSPECTION 15 2 1 1 REMOVING FROM PACKAGING 15 2 ...

Page 4: ...LOC S OPERATION 33 3 4 3 UNIT 34 3 4 3 1 MASS FLOW VS VOLUME FLOW 35 3 4 3 2 VOLUMETRICALLY BASED MASS FLOW UNITS 36 3 4 3 3 VOLUMETRICALLY BASED MASS FLOW UNITS AT VARIOUS REFERENCE TEMPERATURES UXXX 37 3 4 3 4 VOLUME FLOW UNITS VLM 37 3 4 3 5 CUSTOMIZING FLOW UNITS AVAILABLE UNDER THE UNIT FUNCTION 38 3 4 4 TARE 39 3 4 4 1 1TARE 40 3 4 4 1 1 MOLBLOC L OPERATION 40 3 4 4 1 2 MOLBLOC S OPERATION 4...

Page 5: ...MON AND STATUS COMMANDS 101 4 3 4 2 MOLBOX RFM COMMANDS 104 4 4 STATUS SYSTEM 129 4 4 1 STATUS REPORTING SYSTEM 129 4 4 1 1 STATUS BYTE REGISTER 129 4 4 1 2 STANDARD EVENT REGISTER 131 5 MAINTENANCE ADJUSTMENTS AND CALIBRATION 133 5 1 PRODUCT OVERVIEW 133 5 2 CALIBRATION OF REFERENCE PRESSURE TRANSDUCERS RPTS 134 5 2 1 PRINCIPLE 134 5 2 1 1 PA AND PM COEFFICIENTS 135 5 2 2 EQUIPMENT REQUIRED 135 5...

Page 6: ...UTE RPT 146 5 6 1 3 DIFFERENTIAL MICRORANGE RPT OPTIONAL 146 5 6 1 4 DISPLAY 146 5 6 1 5 POWER SUPPLY 146 5 6 1 6 MICRO BOARD 146 5 6 1 7 VALVING MODULE 146 5 6 1 8 MAIN BOARD 147 5 6 1 9 COOLING FAN 147 6 TROUBLESHOOTING 149 6 1 OVERVIEW 149 7 APPENDIX 155 7 1 CONVERSION OF NUMERICAL VALUES 155 7 1 1 PRESSURE 155 7 1 2 TEMPERATURE 155 7 1 3 FLOW 156 7 2 WARRANTY STATEMENT 159 8 GLOSSARY 161 ...

Page 7: ...ssure Units of Measure Available 73 Table 16 Security Levels Functions NOT Executed Per Function Level 81 Table 17 Security Levels Functions NOT Executed Per Function Level Continued 82 Table 18 COM1 and COM2 Available Settings 88 Table 19 COM1 DB 9F Pin Designation 96 Table 20 COM2 DB 9M Pin Designation 97 Table 21 Command Summary 98 Table 22 Error Messages 100 Table 23 Status Byte Register 129 T...

Page 8: ...ic Schematic LEAK CHECK molbox 48 Figure 9 molbox RFM Internal Pneumatic Schematic SYSTEM LEAK CHECK CHECKING OFFSET AND STABILITY molbloc L operation 50 Figure 10 molbox RFM Internal Pneumatic Schematic SYSTEM LEAK CHECK CHECKING OFFSET AND STABILITY molbloc S operation 52 Figure 11 molbox RFM Internal Pneumatic Schematic molbloc S OPERATION BPR ON 92 Figure 12 molbox RFM Internal Pneumatic Schem...

Page 9: ...ng guide Use it to troubleshoot unexpected molbox RFM behavior based on the symptoms of that behavior Certain words and expressions have specific meaning as they pertain to molbox RFM Section 8 is useful as a quick reference for exact definition of specific words and expressions as they are used in this manual For those of you who don t read manuals go directly to section 2 3 initial setup to set ...

Page 10: ...molbox RFM OPERATION AND MAINTENANCE MANUAL 1998 2007 DH Instruments a Fluke Company Page VIII N NO OT TE ES S ...

Page 11: ...ity and lower cost are the primary considerations A second model molbox1 is available for applications where higher accuracy is the most important requirement 1 1 1 MOLBLOC FLOW ELEMENTS Two different types of molblocs may be used with molbox RFM molbloc L laminar and molbloc S sonic 1 1 1 1 MOLBLOC L FLOW ELEMENT molbloc L is the original molbloc laminar flow element molbloc L covers the lower po...

Page 12: ...tane Butn Carbon Monoxide CO Helium He Oxygen O2 Carbon Dioxide CO2 Carbon Tetrafluoride CF4 Octofluorocyclobutane C4F8 Ethane C2H6 Ethylene C2H4 Fluoroform CHF3 Hexafluoroethane C2F6 Hydrogen H2 Methane CH4 Nitrous Oxide N2O Propane C3H8 Sulfur Hexafluoride SF6 Xenon Xe With molbloc S Nitrogen N2 Air dry and humid Pressure Connections Quick connectors equivalent to Swagelok QM Series QM2 B200 Pre...

Page 13: ...ting pressure and absolute and differential pressure associated with molbloc L operation depend on the molbloc used and its pressure dependent calibration options see Section 1 2 4 1 2 Measurement Update Rate 1 second Range 0 to molbloc full scale depending on gas and molbloc pressure dependent calibration type see Section 1 2 4 1 2 Resolution 0 01 FS Linearity 0 23 of reading from 10 to 100 FS 0 ...

Page 14: ...cted stability for a specific molbox RFM should be established from experience 3 Measurement Uncertainty Accuracy Maximum deviation of the molbox RFM flow indication from the true value of the flow through the molbloc including precision stability and DHI calibration standard measurement uncertainty 1 2 4 1 2 molbloc L PRESSURE DEPENDENT CALIBRATION TYPES See your molbloc s Calibration Report to d...

Page 15: ...ssure 325 to 525 kPa absolute 48 to 76 psia upstream of molbloc Not available 50 kPa 7 5 psi Downstream Atmospheric pressure 95 to 105 kPa 13 8 to 15 2 psia downstream of molbloc 12 5 kPa 1 8 psi 80 kPa 12 psi Single P low pressure non N2 gases only Any specified single molbloc upstream pressure between 200 and 325 kPa absolute 29 to 48 psia 5 kPa 725 psi 50 kPa 7 5 psi Single P high pressure non ...

Page 16: ...0 2 000 10 000 7 000 Carbon Tetrafluoride CF4 10 50 100 200 500 1 000 4 000 600 10 000 12 000 3 000 36 000 25 000 Hexafluorethene C2F6 10 50 100 200 500 1 000 2 000 600 6 000 1 200 6 000 4 000 FLUORO CARBONS Trifluoromethane CHF3 10 50 100 200 500 1 000 4 000 600 10 000 12 000 4 000 38 000 30 000 Air Air 10 50 100 200 500 1 000 5 000 10 000 30 000 100 000 Carbon Dioxide CO2 10 50 100 200 500 1 000...

Page 17: ...oride CF4 20 100 200 400 1 000 2 000 3 700 1 200 12 000 2 400 12 000 7 300 N A Hexafluorethene C2F6 25 100 15 120 30 250 50 600 150 2 000 300 1 800 1 500 6 000 3 000 N A FLUORO CARBONS Trifluoromethane CHF3 25 125 240 30 450 60 1 200 150 2 500 4 000 1 500 12 000 3 000 12 000 8 800 N A Air Air 20 100 200 400 1 000 2 000 10 000 20 000 40 000 7 200 N A Carbon Dioxide CO2 25 125 250 500 1 250 2 500 6 ...

Page 18: ...lbloc L SIZES mm in 5E3 AND LOWER 1E4 3E4 1E5 A 58 50 2 303 74 50 2 933 74 50 2 933 B 16 00 0 630 24 00 0 945 24 00 0 945 C 32 00 1 260 SQ 48 00 1 890 SQ 48 00 1 890 SQ D 68 84 2 750 80 00 3 150 80 00 3 150 E 19 06 0 750 28 00 1 102 28 00 1 102 F 124 00 4 881 157 00 6 181 164 00 6 458 G 1 4 in VCR M 1 4 in VCR M 1 2 in VCR M ...

Page 19: ...he molbloc including precision stability and DHI calibration standard measurement uncertainty 1 2 4 2 1 molbloc S RANGES molbloc S flow ranges are defined by the molbloc s Pressure to Flow Conversion Ratio KF the absolute pressure that can be delivered upstream of molbloc S the downstream pressure and the acceptable back pressure ratio see Section 3 1 2 KF is expressed in units of sccm kPa and def...

Page 20: ...3 Minimum upstream pressure to achieve critical flow with atmospheric pressure approximately 100 kPa downstream of molbloc S no vacuum Table 5 Minimum molbloc S Critical Flow slm at Various molbloc S Downstream Pressures MINIMUM molbloc S CRITICAL FLOW SLM 0 C WITH molbloc DOWNSTREAM PRESSURE OF 1 molbloc S DESIGNATO R 5 kPa 0 7 psia 10 kPa 1 5 psia 25 kPa 3 5 psia 50 kPa 7 psia 100 kPa 15 psia 11...

Page 21: ...y molbloc S is separate from the list of molbloc L gases and may be more limited DHI calibration capability is not maintained at all times for all gases on all molbloc sizes Check for availability before ordering calibrations molbloc S calibrations are performed over flow ranges corresponding to one of two pressure ranges summarized in Table 6 Table 6 molbloc S Calibration Types CALIBRATION TYPE O...

Page 22: ... KF16 FLANGE KF16 FLANGE KF40 FLANGE KF40 FLANGE H 100 0 3 94 100 0 3 94 84 0 3 31 84 0 3 31 84 0 3 31 84 0 3 31 154 0 6 06 154 0 6 06 I 128 0 5 04 128 0 5 04 128 0 5 35 128 0 5 35 128 0 5 35 128 0 5 35 236 0 9 29 236 0 9 29 J 73 0 2 87 73 0 2 87 73 0 2 87 73 0 2 87 73 0 2 87 73 0 2 87 106 0 4 17 106 0 4 17 K 167 5 6 59 167 5 6 59 171 0 6 73 171 0 6 73 171 0 6 73 171 0 6 73 290 0 11 42 290 0 11 42...

Page 23: ...LS 1 2 5 1 FRONT PANEL The front panel assembly provides a 2 x 20 vacuum fluorescent display a membrane keypad for local user interface and a SOFT ON OFF key 1 Display 2 Multi function Keypad P 3 Remote Communication Indicator 4 SOFT ON OFF Key and Indicator Figure 1 molbox RFM Front Panel ...

Page 24: ...nications interfaces and the power connection module 1 Quick connectors to molbloc pressure connections color coded 2 Electrical power connector IEC320 313 3 IEEE 488 GPIB connector for host communications 4 COM1 RS232 connector for host communications 5 Electrical connection to molbloc 6 COM2 RS232 connector for communications with an external device 7 Product label on bottom of case Figure 2 mol...

Page 25: ...rough quick connector stem 101889 1 General Accessories CD white Important Includes system support software and documentation 102987 Equivalent to Swagelok P N SS QM2 S 200 2 2 SITE REQUIREMENTS Install molbox RFM on any stable surface at a convenient height The front feet are extendible so that the unit can be inclined for easier viewing The molbox RFM can also be mounted in a standard 19 in rack...

Page 26: ...ve If a DUT is located upstream of the molbloc and is contaminated contaminates may flow from the DUT to the molbloc and alter the molbloc calibration If the DUT must be connected upstream of the molbloc be sure it is clean before flowing and consider installing a filter between the DUT and the molbloc 2 3 INITIAL SETUP 2 3 1 PREPARING FOR OPERATION To prepare molbox RFM for check out and operatio...

Page 27: ...calibration type Care should also be taken to make sure that the pressure and flow supplied to the molbloc are always low enough to avoid over pressuring the molbox RFM RPTs see Sections 1 2 2 3 1 6 If a DUT upstream of the molbloc is operated at high pressure a pressure reducing regulator should be connected between the DUT and the molbloc to ensure that even momentary high pressure spikes do not...

Page 28: ...ould be included between the pump and the molbloc S It is preferable to install a check valve with very low cracking pressure between the molbloc and the vacuum shut off valve Adaptor kits are available from DHI to make connections from the molbloc or molstic fittings to other common connector types Ask you DHI Sales Representative about your specific adaptor requirements Operating at pressures ot...

Page 29: ...q If the molbox RFM is equipped with the microrange option and the option is currently active the bottom line left side of the display is mDP Observe the differential pressure value following this indication see Section 3 4 5 It should be 0 50 Pa 0 004 psi If the indication is different from zero by more than 50 Pa 0 004 psi the microrange differential RPT may be out of calibration and service may...

Page 30: ...For molbloc L operation the pressure measuring RPTs should be tared at the operating line pressure see Section 3 4 4 1 Operating pressure should be within the limits of the molbloc calibration type see Sections 1 2 4 1 2 and 1 2 4 2 2 The gas type selected should be the gas flowing through the molbloc see Section 3 4 2 For best accuracy the gas type should be a gas with which molbloc has been cali...

Page 31: ...approximately 0 5 That is the absolute pressure downstream of the nozzle must be less than one half of the absolute pressure upstream of the nozzle Empirical study of the venturi nozzles used in molbloc S shows that the actual choking ratio or maximum BPR for critical flow varies between about 0 4 and 0 9 as a function of the Reynolds number Re over which the molblocs are used molbox RFM continual...

Page 32: ... when steady state flow conditions are present so that a valid comparison reading can be made 3 1 3 1 molbloc L OPERATION In molbloc L operation the Ready Not Ready indication also helps guard against using molblocs above their valid range by monitoring the Reynolds number of the flow If the Reynolds number of the current flow exceeds 1 300 the Ready indicator flashes The current Reynolds number v...

Page 33: ...si A three way valve and on board logic automatically put the low differential RPT into and out of service This allows it to be used as the source of differential pressure values whenever differential pressure is under 12 5 kPa 1 8 psi and bypassed for protection from overpressure when differential pressure exceeds 13 5 kPa 2 psi see Figure 3 With automatic microrange operation ON the microrange o...

Page 34: ...TIAL RPT MICRORANGE OPTION The microrange option low differential RPT has no overpressure warnings or alarms in normal operation It is to the extent possible protected from overpressure automatically and transparently as it is put into and out of service using the molbox RFM on board valving In run calibration operation see Section 5 2 4 1 the microrange RPT has an OVERPRESSURE function whose oper...

Page 35: ...3 4 7 and 3 6 7 Possible indications include Blank NO character The microrange option is currently OFF or the molbox RFM is not equipped with the microrange option m Automatic microrange is ON see Section 3 4 7 d Manual microrange is ON and the differential pressure reading being used to calculate flow is coming from the microrange differential RPT see Section 3 6 7 a flashing Manual microrange is...

Page 36: ...HI When molbloc S is in the BPR OFF mode see Section 3 6 9 BPR is not monitored and invalid flow values may be displayed in the molbloc S MAIN run screen with no indication that a the BPR value is high 1 Ready Not Ready indication when Ready increasing or decreasing indicating direction of flow rate evolution when Not Ready P when BPR is higher than choking limit see Section 3 1 2 2 FLOWWW Numeric...

Page 37: ... The SETUP menu is for more frequently used functions The SPECIAL menu is for less frequently used and internal functions These keys enter numerical values when editing Figure 4 Keypad Layout Pressing the ENTER key generally causes execution or forward movement in the menu tree Pressing the ESCAPE key generally allows movement back in the menu tree and or causes execution to cease or suspend witho...

Page 38: ... RFM into a dormant mode in which the display is turned OFF but power is still supplied and OVERPRESSURE functions are still active When molbox RFM is ON the ON OFF indicator is ON continuously When molbox RFM is SOFT OFF the ON OFF indicator blinks every 5 seconds When molbox RFM is SOFT OFF receiving a remote command turns it ON When molbox RFM is SOFT OFF an overpressure conditions turns it ON ...

Page 39: ...ther values are displayed Run the TARE LEAK CHECK PURGE AutoZ and BPR functions Display the current pressure measurements first press Display the current molbloc temperature measurements second press Define the DISPLAY function for the second line of the molbox RFM display Choices include rate average hi lo totalize 2 nd unit deviation freeze clean Set change a DUT gas correction factor K factor S...

Page 40: ...n is active molbox RFM performs all of its flow calculations normally but multiplies the current flow value by the value of the K factor prior to displaying it The gas selected on molbox RFM which is displayed in the upper right corner of the molbox RFM display should always be the gas that is actually flowing through the molbloc K factors or gas conversion factors are based on the properties of t...

Page 41: ...geometric characteristics gas pressures gas temperature specific characteristics of the flowing gas The gas characteristics include gas density under standard conditions change in gas density with pressure and temperature gas viscosity under standard conditions when needed changes in gas viscosity with pressure and temperature Proprietary algorithms are used to calculate gas density and viscosity ...

Page 42: ...olbloc L OPERATION To specify the gas flowing through molbloc L press GAS The display is 1inert 2flammable 3toxic 4other The gases available are grouped in categories to facilitate finding a specific gas and as a reminder to the user when selecting a gas that may require special precautions in use There is a list of gases under each category For example the 1inert selection displays 1N2 2He 3Ar Se...

Page 43: ...nt pressure and temperature Users who do not have the W value available can use DHI s free Unit of Measure Converter software utility or COMPASS for molbox calibration software to calculate W from measured pressure temperature and relative humidity Visit www dhinstruments com or see your DHI sales representative for a copy of the Unit of Measure Converter software utility Air relative humidity pre...

Page 44: ...riate non zero value see section immediately above if humid air is being flowed The gas selected on molbox RFM should always be the gas that is flowing through the molbloc molbloc molbox does not use K factors or gas conversion factors between gases When calibrating or testing a device with a surrogate gas molbox RFM should be set to the surrogate gas The K factor or gas conversion factor if used ...

Page 45: ... order see Section 3 4 3 5 Many different types of flow units are commonly used including a wide variety of mass flow units as well as volume flow units Please read Sections 3 4 3 1 through 3 4 3 5 for additional information on the various unit definitions and how they are handled by molbox RFM before making unit of measure selections 3 4 3 1 MASS FLOW VS VOLUME FLOW COMPASS for molbox software us...

Page 46: ... molbloc causes the temperature of the gas that flows through the molbloc to take on the molbloc temperature Therefore the temperature of the gas as it exits the molbloc is the same as the molbloc temperature If the volume flow measurement point is not immediately downstream of the molbloc the best estimate of gas temperature may be ambient temperature or the temperature of the device or bath used...

Page 47: ...4 3 3 In early 1996 SEMI a semiconductor industry interest group adopted standard E12 96 which specifies that perfect units be used for volumetrically based mass flow units To comply with the SEMI standard pccm should be used rather than sccm To purchase a copy of the relevant SEMI standard contact SEMI at telephone 415 964 5111 or email semihq semi org 3 4 3 3 VOLUMETRICALLY BASED MASS FLOW UNITS...

Page 48: ...ser The next screen is to edit the volume flow pressure in the current pressure unit of measure Pressing ENTER accepts the edited value as the volume flow pressure and returns to the MAIN run screen with the selected volume flow unit and gas temperature and pressure active Volume unit gas pres 101 325 kPa The temperature and pressure units of measure used to specify volume flow conditions can be c...

Page 49: ...and using the true compressibility factor of the gas 2user mass flow units for which standard conditions are a user settable temperature standard atmosphere and using the true compressibility factor of the gas 3perfect mass flow units for which standard conditions are temperature of 0 C standard atmosphere and assuming a compressibility factor of 1 for all gases 4vlm volume flow units See Sections...

Page 50: ...ately for the two molbloc types below 3 4 4 1 1 molbloc L OPERATION PURPOSE To zero the molbox RFM differential pressure reading at the molbloc operating pressure Zeros the differential between the two high pressure absolute transducers as well as the microrange transducer if present PRINCIPLE The molbox RFM TARE function can be considered the equivalent of the ZEROING function performed on many i...

Page 51: ...he tare value is the differential value read The differential transducer will be corrected by subtracting the tare value from the current reading 1 High Isolation Open 2 Low Isolation Closed 3 Bypass Open 4 Mirorange Bypass Open Figure 5 molbox RFM Internal Pneumatic Schematic TARING UPSTREAM molbloc L OPERATION OPERATION At a minimum the TARE function should be executed whenever the operating pre...

Page 52: ... tare value resulting from this execution of the TARE function Pa 3 Microrange tare value currently in use Pa 4 New microrange tare value Pa OldT 44Pa m 20 NewT 36Pa m 20 Press ENTER to activate the new tare and return to the MAIN run screen Press ESCAPE to return to the TARE display without activating the new tare leaving the old tare active The tare screen shows the upstream and downstream RPT r...

Page 53: ...box RFM employs internal valving to direct the upstream pressure to both RPTs and the average of the two readings is used as the measured molbloc upstream pressure To take advantage of this RPT averaging the molbox RFM must be in either BPR OFF or Auto BPR mode see Section 3 6 9 molbox RFM dynamically tares the two RPT readings when they are connected together so the user can view the live average...

Page 54: ...erential value is always in Pascal Pa 4 Tare message OK If tare is less than 300 Pa CHECK if tare is between 300 and 1250 Pa NEED CAL if tare is greater than 1250 kPa 201 032 kPa 201 013 T 19 3 Pa OK The tare screen shows the upstream and downstream RPT readings WITHOUT the current tare applied The P T screen shows the RPT readings WITH the tare applied see Section 3 4 5 3 4 4 2 2Purge PURPOSE To ...

Page 55: ...the molbox RFM internal volume can be purged by simply flowing the new gas in the normal flowing configuration The flow resistance through the molbloc creates a differential pressure which causes flow through the molbox RFM to occur purging it with the new gas 1 High Isolation Open 2 Low Isolation Open 3 Bypass Open 4 Mirorange Bypass Open Figure 7 molbox RFM Internal Pneumatic Schematic PURGING O...

Page 56: ... 3 4 4 3 3Leak Check PURPOSE To access the molbox LEAK CHECK and SYSTEM LEAK CHECK functions which use molbox RFM s pressure and flow measurement capabilities to check molbox RFM and or the system to which it is connected for leaks PRINCIPAL molbox RFM is used both as a tool to accurately measure unknown flow values and as a calibration standard to calibrate other devices by comparison Leaks withi...

Page 57: ...ENTER The molbox RFM internal valving is in its normal measuring configuration see Figure 3 This display is intended to assist the operator in setting the leak check pressure Apply the maximum differential pressure across the molbloc that is normally encountered during flow measurement while working at your typical absolute working pressure Neither pressure should be less than atmosphere Use the D...

Page 58: ...unt down in seconds 347 466 kPaa 35 459 1 03579 1 WAIT 60 molbox RFM counts down for 60 seconds while monitoring the ratio of the two pressures and then determines whether an internal leak was present A significant leak in a pressure isolation valve or a bypass valve between the two channels will cause the ratio between the two pressures to vary The molbox RFM LEAK CHECK function should end with t...

Page 59: ...lp determine whether a leak is present upstream or downstream of the molbloc Since molbloc S is not capable of calculating meaningful flow values with the very small differential pressure present during this test the SYSTEM LEAK CHECK operates differently for molbloc L and molbloc S operation as described in the OPERATION sections immediately below The SYSTEM LEAK CHECK function uses molbox RFM s ...

Page 60: ...em by connecting a cap to the MFC outlet fitting or by connecting a shutoff valve downstream If the MFC valve is closed most MFCs have normally closed valves when the operating pressure is applied from the upstream side most of the gas will be stopped by the MFC valve and will not immediately fill the volume between the MFC valve and the downstream cap or valve If this happens the gas may leak by ...

Page 61: ...Current measured flow 3 Time remaining in the leak check in seconds 347 592 kPaa 347 583 0 101 sccm 30 molbox RFM measures pressure and flow for a 40 second countdown After the countdown has elapsed molbox RFM displays its conclusion from the measurements The display will be either possible system upstream leak or possible system downstream leak or System passed system leak check Upstream and down...

Page 62: ...CS Keep in mind that the valves in most MFCs are not intended to provide a complete gas shutoff and so they may not be suitable to close off the test system If an MFC is downstream of the molbloc and its downstream port is open to atmosphere it is best to close the system by connecting a cap to the MFC outlet fitting or by connecting a shutoff valve downstream If the MFC valve is closed most MFCs ...

Page 63: ...lumes may be quite large it is difficult to predict what size pressure rate of change is acceptable to avoid significant flow errors Your best guide may be to run the SYSTEM LEAK CHECK often with your hardware find a typical rate of change which represents a sound setup and attempt to match that rate each time In any case you should be able to achieve a rate of change smaller than 0 01 second of t...

Page 64: ...ive to the AutoZ standard Pstd 0 The AutoZ function manages the determination storage and application of Poffset for both molbox RFM RPTs in absolute mode The AutoZ handles both molbox RFM RPTs simultaneously as they are of the same range and always used together The source of Pstd 0 must be an absolute pressure nominally atmospheric pressure with uncertainty significantly better than that of the ...

Page 65: ...4 1 OPERATION To access the molbox RFM AutoZ function press TARE 4AutoZ The display is 1 Active RPT designator 2 Indication of whether AutoZ is currently ON or OFF for this RPT and measurement mode 1off 2view 3edit 4run ON Select 1off or 1on to change the AutoZ status Select 2view to view the current values of Poffset for the two RPTs Poffset should be zero when the molbox RFM is new or has just b...

Page 66: ... read automatically from a DHI RPMx connected to molbox RFM s COM2 communications port When AutoZ is run the molbox RFM internal valves are actuated to connect both molbox RPTs to the Hi port on the molbox RFM rear panel see Figure 21 in Section 5 2 4 1 Be sure the Hi port is fully open to atmosphere when running AutoZ Note that the molbox RFM quick connectors and molbox to molbloc pressure lines ...

Page 67: ...e as the display and press ENT molbox RFM logs the readings and calculates a new AutoZ offset value The next display is 1 Current previous value of Poffset for the upstream 1 Hi RPT 2 Current previous value of Poffset for the downstream 2 Lo RPT 3 New value of Poffset for the upstream 1 Hi RPT for the AutoZ that was just run 4 New value of Poffset for the downstream 2 Lo RPT for the AutoZ that was...

Page 68: ...at was just run 4 New value of Poffset for the downstream 2 Lo RPT for the AutoZ that was just run Old 0 0 Pa 0 0 New 3 7 Pa 2 6 Press ENT to activate the new values of Poffset or ESC to start over The value of Poffset is always displayed and entered in Pascal Pa 3 4 4 5 5BPR molbloc S OPERATION ONLY PURPOSE To quickly measure the molbloc S upstream and downstream pressure and calculate and displa...

Page 69: ... s low differential pressure RPT In molbloc S operation the flow is calculated from the molbloc S upstream pressure The upstream pressure may be read by either one or both of the RPTs depending on which BPR mode is used see Section 3 6 9 When molbox RFM is in a valve state called BPR OFF the molbloc S downstream pressure is not measured and both RPTs are used to measure the molbloc S upstream pres...

Page 70: ... MAIN run screen press ESCAPE To change the pressure and or temperature unit of measure see Sections 3 5 2 and 3 5 3 OPERATION molbloc S operation 1 The current pressure read by the upstream left and downstream right RPTs and the current pressure unit of measure middle In BPR OFF or Auto modes tare is automatically applied to these readings In BPR ON mode tare is never applied 2 Arrow to indicate ...

Page 71: ...sured since HI LO reset see Section 3 4 6 3 This function is used to keep track of the minimum and maximum flow observed over a period of time or to monitor whether a flow min max limit has been exceeded TOTAL Totalizes the mass or volume flowed over a period of time see Section 3 4 6 4 Used to measure total mass or volume over a period of time Can be useful in calibrating or verifying a totalizin...

Page 72: ...d in this section but the display will return to normal when the BPR returns to a usable level for molbloc S measurements see Section 3 1 2 The default DISPLAY function is RATE which causes the second line of the display to show R followed by the current rate of change of flow in current flow unit of measure per second see Section 3 4 6 1 3 4 6 1 1RATE PURPOSE To activate the RATE DISPLAY See Sect...

Page 73: ... DISPLAY active With the AVERAGE DISPLAY active the MAIN run screen is 1 Average flow measured over last completed averaging period 2 Standard deviation of last completed averaging period 3 Countdown in seconds until completion of on going averaging period 101 99 sccm N20 δ 0 06 18 sec The AVERAGE DISPLAY has a second screen that allows the instantaneous flow readings to be viewed while an averagi...

Page 74: ...occurs The HI LO record can be reset at any time by pressing ENTER allowing a HI LO reset without going back through the DISPLAY menu Changing the flow unit of measure the gas the K factor or running a TARE function while in HI LO resets the HI LO record To go to a DISPLAY other than HI LO press DISPLAY and make a new DISPLAY choice 3 4 6 4 4TOTAL TOTALIZER PURPOSE To activate the TOTALIZER DISPLA...

Page 75: ...w totalizing run from the totalizing complete screen press ENTER This clears the previous total resets to the totalizing timer and starts totalizing Certain functions cannot be executed while totalizing These functions include change K change gas change flow unit of measure tare If Access restricted while totalizing is displayed when a function key is pressed during totalizing the function is one ...

Page 76: ...20 0 1013 slm The reference temperature setting for the user units i e uccm and ulm see Section 3 4 3 3 and the temperature and pressure settings for volume units see Section 3 4 3 4 apply to the units in the main UNIT selections as well as the UNIT DISPLAY selection Therefore it is not possible to simultaneously display user units or volume units with different reference temperatures and or press...

Page 77: ...nt flow from target value in of reading 100 53 sccm N20 D 0 53 T 100 00 Pressing ENTER from the MAIN run screen when the DEVIATION DISPLAY is active goes directly to the target editing screen This allows the target value to be changed without going through the DISPLAY menu The DEVIATION DISPLAY target value is the value from which deviations D are measured by the DEVIATION DISPLAY following D curr...

Page 78: ...LAY is active the FREEZE value defaults back to zero To go to a DISPLAY other than FREEZE press DISPLAY and make a new DISPLAY choice 3 4 6 8 8CLEAN PURPOSE To activate the CLEAN DISPLAY See Section 3 4 6 PRINCIPLE OPERATION To activate the CLEAN DISPLAY press DISPLAY and select 8clean Selecting 8clean returns to the MAIN run screen with the CLEAN DISPLAY active With the CLEAN DISPLAY active the M...

Page 79: ...s flow can come from the difference between the upstream and downstream RPTs the microrange differential RPT or a combination of the two during the transition from one method to the other The microrange option can also be operated in a manual mode see Section 3 6 7 OPERATION The MICRO function can be operated at any time from the main run screen Pressing MICRO causes automatic microrange to turn O...

Page 80: ...lbox EEPROM and then display a summary of the molbloc identification header including range designation serial number and calibration date This screen is displayed for 5 seconds before operation returns to the main run screen If molbox RFM is unable to establish communications with a molbloc the display is molbloc not detected ENTER searches again Pressing ESCAPE returns to the run screen Pressing...

Page 81: ... S Size Designation and Pressure to Flow Conversion Ratio KF KF sccm kPa molbloc S SIZE DESIGNATION 50 5E1 S 100 1E2 S 200 2E2 S 500 5E2 S 1 000 1E3 S 2 000 2E3 S 5 000 5E3 S 10 000 1E4 S 3 4 9 RES PURPOSE To set the resolution of molbox RFM s display of the flow through the molbloc and other flow display and entry values PRINCIPLE The resolution with which the flow measured by molbox RFM is displ...

Page 82: ...OT have direct function keys These functions include 1flowU To customize the flow unit choices available under UNIT see Sections 3 5 1 and 3 4 3 2presU To select change the unit of measure in which molbox RFM displays pressure values see Section 3 5 2 3tempU To select change the unit of measure in which molbox RFM displays temperature values see Section 3 5 3 4molbloc To initialize a molbloc when ...

Page 83: ...Units of Measure Available 1SI 2Other 3User 1Pa 2kPa 3mPa 4mbar 5bar 6mmHg 7mmWa 1psi 2psf 3inHg 4inWa 5kcm2 1user 3User User defined unit The user unit is defined in terms of user units Pa when the user unit is selected See Section 7 1 1 for definition of the pressure unit conversions used by molbox RFM 3 5 3 3tempU PURPOSE To select the unit of measure in which molbox RFM displays temperature va...

Page 84: ...h which the molbloc has been calibrated OPERATION To access the molbloc function press SETUP and 4molbloc Operation is similar to operation of the molbloc direct function key see Section 3 4 8 However when in the molbloc identification screen pressing ENTER causes a list of the gases for which the molbloc has specific calibration coefficients to be displayed The gases are listed using their chemic...

Page 85: ...d by setting an adder and a multiplier The adder FA and multiplier FM adjust the displayed value of the flow through the molbloc as calculated by the molbox RFM following corrected flow calculated flow FM FA If a K factor is active see Section 3 4 1 the adder and multiplier are applied to the calculated flow before the K factor is applied Using the Flow ADJ Function with molbloc L to Handle a Gas ...

Page 86: ...der and multiplier of the ADJ function if different from 0 and 1 alter the flow readings made by the molbox The ADJ function is always ON When using adders and multipliers great caution should be taken to ensure that they are entered and changed correctly and that they are 0 and 1 if no adder or multiplier effect is desired The ADJ function is restricted in all User Security Levels except none to ...

Page 87: ...default or factory values PRINCIPLE molbox RFM stores its user definable settings in non volatile memory The reset menu allows the user to selectively or completely reset these settings to factory defaults Reset clears settings that the user may have made and should be used only to restore the molbox RFM to a known state molbox RFM will go through its reboot routine after any type of reset is exec...

Page 88: ... to upstream pressure see Section 3 4 4 1 1 Flow adder to 0 and flow multiplier to 1 see Section 3 5 6 Resolution to 0 01 see Section 3 4 9 BPR mode to Auto see Section 3 6 9 3 6 1 2 2UNITS PURPOSE OPERATION To access Reset Units press SPECIAL and select 1reset 2units Reset Units clears and sets to default all UNIT OF MEASURE functions These include Six flow units of measure selectable from UNIT t...

Page 89: ...ransducers RPTs see Section 5 2 If the molbox RFM has been recalibrated at any time since its original factory calibration the recalibration adjustment was done using these user calibration coefficients The RPT cal coefficient defaults are Upstream and downstream absolute RPTs Adder 0 Multiplier 1 Calibration Date 19980101 Microrange differential RPT Adder 0 Multiplier 1 Calibration Date 19980101 ...

Page 90: ...nvironments as follows None This level is intended for use only by the system manager and or calibration facility It allows access and editing in all areas including critical metrological information and other settings that affect measurement integrity Low Low security is designed to protect the specific metrological information and SYSTEM DIAGNOSTIC AND MAINTENANCE functions of the system against...

Page 91: ...y strokes marked by Table 16 Security Levels Functions NOT Executed Per Function Level KEYS LOW MEDIUM HIGH K GAS UNIT UNIT change temperature pressure conditions TARE access menu TARE 1tare select tare pressure TARE 2purge change purge time TARE 4AutoZ 1on off TARE 4AutoZ 3edit TARE 4AutoZ 4run P T DISPLAY DISPLAY change times target MICRO molbloc RES SETUP 1flowU SETUP 2presU SETUP 3tempU SETUP ...

Page 92: ...e password setting To access the USER LEVEL function press SPECIAL 2level If NO password yet exists or if the correct password has been entered the display is 1change user level 3edit password Selecting 1change user level brings up the restriction menu Restriction 1none 2low 3medium 4high Select the desired restriction level or press ESCAPE to return to the current run screen Selecting 2edit passw...

Page 93: ...ttempt to protect the RPTs against overpressure molbox RFM continuously monitors the pressure read by the RPTs When the pressure passes the level set by the UL function molbox RFM warns the operator by sounding an audible alarm Beyond the UL limit there is an overpressure limit which is not user selectable If the pressure reaches the overpressure limit molbox RFM uses its internal valves to isolat...

Page 94: ...ation The upper limit and overpressure functions are intended to use molbox RFM s features to the extent possible to protect the molbox RFM reference pressure transducers RPTs against overpressure The system is not failsafe and an overpressure causing fatal damage to the RPTs can still occur Ultimately protection of the RPTs is the responsibility of the user RPTs damaged by overpressure are not co...

Page 95: ...ill activate to dim the screen Set zero to eliminate the SCREEN SAVER function Setting screen saver time to zero eliminates the SCREEN SAVER function so that the display remains permanently at full brightness The display may also be completed suppressed using the SOFT ON OFF key see Section 3 3 3 3 6 5 2 2SOUND PURPOSE To adjust or suppress the molbox RFM keypad valid and invalid key press sounds ...

Page 96: ...roductory screen molbox RFM also allows the user to store a unique twelve character alpha numeric ID number This feature is frequently used to assign an organizational control ID e g an asset number tool number standard number etc The ID function allows the ID number to be viewed and edited It also displays the molbox RFM factory serial number OPERATION To access the ID function press SPECIAL and ...

Page 97: ...E To configure the molbox RFM COM1 COM2 and IEEE 488 communication ports To test COM1 and COM2 communications PRINCIPLE The molbox RFM has two RS232 communications ports referred to as COM1 and COM2 and a single IEEE 488 port COM1 and the IEEE 488 port are for communicating with a host computer see Section 4 1 COM2 is reserved for communicating with an external device e g a multimeter second molbo...

Page 98: ...he end of all transmitted messages It looks for a line feed and or assertion of the EOI line to terminate incoming messages see Section 4 2 2 3 6 6 3 RS232 SELF TEST The RS232 self test is provided to check the molbox RFM COM ports and the interface cable independently of an external device or computer If you are having difficulty communicating with molbox RFM from a host computer using RS232 the ...

Page 99: ...on 1 2 4 1 1 for a complete description of microrange principles The differences between automatic microrange and manual microrange are that in manual microrange The differential pressure value used to calculate flow is either 100 difference between the upstream and downstream absolute RPTs P1 P2 or 100 readings from the microrange differential RPT No special transitioning from one method to the o...

Page 100: ... reference pressure transducers in order to predict the pressure at height the height of the molbloc when the molbloc is at a level other than the molbox RFM s reference level PRINCIPLE molbox RFM measures absolute and differential pressure in molbloc flow elements The molbox RFM reference pressure transducers RPTs are calibrated with the height of the rear panel pressure quick connectors as the p...

Page 101: ...disabled when running AutoZ see Section 3 4 4 4 2 and in the calibration run screen see Section 5 2 4 1 3 6 9 9BPR PURPOSE In molbloc S operation to select the molbox RFM BPR back pressure ratio measurement mode PRINCIPLE When molbloc S elements are used with molbox RFM the RPT which is normally used to read molbloc downstream pressure may be pneumatically connected to either the molbloc S nozzle ...

Page 102: ...umatic Schematic molbloc S OPERATION BPR OFF Ideally the user is able to monitor the BPR with BPR ON while setting flows and pressures and once the flow is established uncertainties can be minimized by turning BPR OFF gaining the benefit of using both RPTs upstream As an alternate to operator switching between BPR ON and BPR OFF molbox RFM has a BPR mode called AUTO that uses on board logic to det...

Page 103: ... until the user changes the BPR mode or activates a function which causes a valve change such as the TARE 5BPR function see Section 3 4 4 5 In BPR OFF mode the flow is calculated from the average of the two RPT pressure readings and the RPT pressures displayed in the P T pressure screen are adjusted using the dynamic tare feature so both pressures are displayed equal to the average value see Secti...

Page 104: ...suring the same pressure The most recent tare that was automatically calculated during the BPR OFF valve state is used to correct the pressures used and displayed in Auto mode until the valves return to the BPR OFF state again This assures that flow measurements remain as consistent as possible during Auto mode valve switching and that the tare value that is most likely to be correct is used at al...

Page 105: ...d operation until the LOCAL command is sent Most remote commands will return a reply within 500 ms You must wait for this reply before issuing another command to the molbox This ensures that the molbox RFM has completed the command An exception to this is the use of any of the IEEE STD 488 2 Common Commands see Section 4 3 4 1 via the IEEE 488 interface common commands all start with an asterisk T...

Page 106: ...age return character while line feed characters are ignored All RS232 responses from the molbox RFM are terminated with a carriage return character and a line feed character Table 19 COM1 DB 9F Pin Designation PIN FUNCTION DESCRIPTION 2 TxD This pin transmits serial data from the molbox RFM to the host 3 RxD This pin accepts serial data from the host computer 5 Grn This pin is the common return fo...

Page 107: ...r is 250 bytes deep The molbox RFM will hold OFF release of the NRFD handshake line until it can service and empty the receive buffer This keeps the buffer from overflowing IEEE 488 commands must be terminated with a single line feed character along with the assertion of the EOI line All IEEE 488 responses from the molbox RFM are terminated with a line feed character along with the assertion of th...

Page 108: ...sure ratio mode when using molbloc S COMn Read or set the configuration of the COM1 or COM2 port DATE Read or set the internal time and date DEVICE EXT Loads information on molbloc connected to molbox RFM into molbox RFM DP Read the differential pressure value being used to calculate flow ERR Read the last error message FA Start a single flow averaging cycle FCOEF Read the coefficient to convert k...

Page 109: ...Read the current tare conditions and the current tare TARESETUP Prepares the unit to tare TARESET Tare the upstream and downstream RPTs and microrange RPT if present or set tare to a given value TEMP Read the current molbloc temperature in the current units TIME Read or set the internal clock time TOTAL Read the progress of or start a new totalize cycle TUNIT Read or set the molbloc temperature un...

Page 110: ...17 Selected gas not available ERR 18 Command not yet available ERR 19 Not supported ERR 20 Not supported ERR 21 User device not defined ERR 22 Pressure is not stable ERR 23 Option not available or installed ERR 24 molbloc not detected ERR 25 Transducer out of calibration ERR 26 COM port failed to initialize ERR 27 Internal device 1 2 or 3 timeout error ERR 29 Busy averaging ERR 30 Fatal mass flow ...

Page 111: ...ands they must have a space instead of an equals sign between the command and any arguments Also unlike the other molbox RFM commands if you are using the IEEE 488 port the query form command is immediately followed by a must be used to get a reply If using the COM1 port and the command is not a query OK will be replied CLS Purpose Clear all of the status and event structures Syntax CLS Remarks Th...

Page 112: ...serial number and the software version Each is separated by a comma Query Reply The version string Example Command Reply IDN DH INSTRUMENTS INC molbox RFM 1001 Ver1 10 dhf OPC Purpose Sets the operation complete bit when all operations have completed Syntax OPC OPC Remarks This command enables the molbox RFM to set the OPC bit in the standard event status register when it has completed all pending...

Page 113: ...valent to pressing SPECIAL on the front panel and selecting 5Reset 1sets This does not affect the communications settings Example Command Reply RST OK using COM1 no reply if IEEE 488 port SRE Purpose Read or set the service request enable register Syntax SRE n SRE Parameters n 0 to 255 This is the decimal representation of the bit s to enable To allow the MAV and ESB bits to assert the SRQ line th...

Page 114: ... 1 4 3 4 2 molbox RFM COMMANDS Purpose To allow the Host computer to communicate with a device connected to the molbox RFM COM2 port Syntax XX Arguments xx The string to send out of the COM2 port It must be less than 40 characters long Remarks The molbox RFM COM2 port can be used to communicate to another RS232 device e g another molbox RFM or a multimeter This allows the user to use one COM port ...

Page 115: ... operation of the unit begins if the previous state of the unit is not known The ABORT command also clears out any previous leak or tare cycle errors Example Command Reply ABORT ABORT See Also FA TARESETUP LEAKCK PURGE AIRW Purpose Read or set the humidity ratio for the gas AIR Syntax AIRW HumidityRatio AIRW Default AIRW 0 00 00 Arguments HumidityRati o The humidity ratio 0 0 1 Remarks The humidit...

Page 116: ...urrent measured flow and flow units avgpres is the average of the upstream and downstream RPTs and units uppres is the upstream RPT pressure measurement and units dnpres is the downstream RPT pressure measurement and units temp is the molbloc temperature and units micropres is the optional microrange RPT pressure measurement and units Example Command Reply ALLR R 1 2 sccm 97 697 kPa a 97 685 kPa a...

Page 117: ... Sent Reply Sent Reply BPR 2 2 0 BPR 1 1 1 1 Errors ERR 6 One of the arguments is out of range See Also 3 6 9 COMn Purpose To set or read the configuration of the COM1 or COM2 ports Syntax COMn baud parity data stop COMn Arguments n The COM port 1 or 2 baud The baud rate This may be 300 600 1200 2400 4800 or 9600 parity The data parity This may be O for odd E for even or N for none data The data w...

Page 118: ...le Command Reply DEVICE EXT EXT Errors ERR 24 ERR 35 ERR 40 ERR 41 A molbloc is not connected to the molbox RFM The molbloc experienced a communications timeout The molbloc experienced a read checksum failure The molbloc data header is corrupted See Also 3 2 8 and 3 3 4 DP Purpose Read the differential pressure value used by molbox RFM to calculate flow Syntax DP Remarks The molbox RFM has upstrea...

Page 119: ...e molbloc flow and standard deviation of the molbloc flow over this period After sending this command you can monitor the averaging cycle by using the FR or SR command to determine when the averaging cycle is complete Once the cycle is done you must use the FRA command to collect the results Example Command Reply FA 20 20 s Errors ERR 6 The period argument is not within the specified limits See Al...

Page 120: ...g cycle that was started earlier using the FA command During the averaging cycle this command will reply BUSY until the averaging cycle is complete Then the reply will be the result of the averaging cycle If the cycle is aborted before it is complete see FA then the data will be lost The data that is returned from the command consists of multiple numeric fields delimited by commas The flow numbers...

Page 121: ...VLM GAS Purpose Read or set the gas type being flowed through the molbloc Syntax GAS gas GAS Arguments gas The gas to use Remarks The gas type being flowed through the molbloc is specified using this command The gas must be supported by the molbox RFM The gas type protocol is the same as the front panel gas definitions A valid molbloc must be connected to the molbox RFM before changing the gas typ...

Page 122: ...fined ID label can be used to allow the user to tag the molbox RFM with a unique identifier This ID is stored in non volatile memory and cannot be erased by a power failure system fault or reset Example Command Reply ID RFM 001 RFM 001 See Also 3 4 5 4 KFACT Purpose Read or set the molbox RFM K factor Syntax KFACT kfactor KFACT Arguments kfactor The new K factor Defaults FACT 1 0 Disabled Remarks ...

Page 123: ... of the leak check the molbox RFM is returned to its normal operating state For the BOX leak check the microrange RPT is normally bypassed inactive unless the optional second argument is given For the SYS leak check the microrange RPT is always bypassed The ABORT command can be used to stop a leak check cycle clear out any previous error messages and return the molbox RFM to its normal operating s...

Page 124: ...Command Reply LOCAL LOCAL See Also REMOTE MEM Purpose Read the memory test status Syntax MEM Remarks On power up a memory test is run to check the integrity of the internal data NVRAM If the memory has been corrupted FATAL MEMORY FAULT will be displayed on power up to alert the user and the memory test status command will return a 0 The command will return a 1 if the memory is OK Example Command R...

Page 125: ...calibration data This data is stored in the molbloc and is downloaded to the molbox RFM on power up The data for the active molbloc is returned in a single comma delimited string in the following order Serial Number Range Designator Range Flow Units Gas Calibration Date yyyymmdd Total PRT Resistance upstream downstream at 0 C Ω PRT Slope dimensionless Upstream PRT Resistance at 0 C Ω Downstream PR...

Page 126: ...AL 0 1 00000 0 1 00000 0 0 1 00000 microrange option Arguments upadder The upstream RPT calibration adder PA from 10 000 to 10 000 Pa upmult The upstream RPT calibration multiplier PM from 0 9 to 1 1 dnadder The downstream RPT calibration adder from 10 000 to 10 000 Pa dnmult The downstream RPT calibration multiplier from 0 9 to 1 1 mradder The optional microrange RPT calibration adder from 10 000...

Page 127: ...2 PCAL PCOEF Purpose Read the coefficient to convert Pascal Pa to the current pressure units Syntax PR Remarks The pressure coefficient PCOEF is a value that is used to convert Pascal units to the current pressure units To use this coefficient multiply it by pressure in Pascal to get pressure in the current units Example Command Reply PCOEF 1 000000e 003 See Also 7 1 1 UNIT PR Purpose Read the nex...

Page 128: ...fferential pressure across the molbloc Example Command Reply Reply PRDP 10 5 kPa RPT is not bypassed it is active 10 5 kPa RPT is bypassed it is inactive Errors ERR 23 The microrange option is not installed See Also 3 1 2 6 DP PR PRHI PRLO PRHI Purpose Read the last measured upstream absolute pressure tare corrected Syntax PRHI Remarks The current upstream pressure value corrected for tare is retu...

Page 129: ...ommand is used to first start the purge cycle and then to query how many seconds are left or if the cycle is complete While the purge cycle is executing a b busy will appear in the third character position of the FR and the SR command replies The PURGE command must be completed or aborted using the ABORT command before performing another operation Example Command Reply PURGE 30 30 sec Command Repl...

Page 130: ...ondition Syntax READYCK 1 READYCK Defaults READYCK 1 Remarks The internal ready check flag is cleared whenever the molbox RFM reaches a Not Ready NR condition The READYCK command will return the status of this flag This flag can be set only by sending the READYCK 1 command while the molbox RFM is in a Ready condition If you send the READYCK 1 command when the molbox RFM is in a Not Ready NR condit...

Page 131: ...ctive The resolution of remote flow measurement replies are always 0 001 FS 0 0001 FS with microrange Example Sent Query reply RES 01 0 010 Errors ERR 6 The argument was out of bounds See Also 3 4 9 RESET Purpose Reset the molbox RFM to the default operating parameters Syntax RESET Remarks The RESET command can be given to return certain molbox RFM settings to a default state This reset correspond...

Page 132: ...r if the molbloc flow is over the maximum Reynolds number of 1 200 allowed for a valid measurement A b will appear if the molbox RFM is busy with a tare leak check or purge cycle which does not allow normal operation Example Command Reply SR NR See Also 3 1 2 4 FA FR READYCK SS TARESET PURGE LEAKCK SS Purpose Read or set the flow stability required for a Ready condition to occur flow unit s Syntax...

Page 133: ...dition see TARESETUP and check the tare conditions before taring the internal transducers see TARESET The returned data will allow the user to determine if the current conditions will allow a valid tare The reply contains three or five fields which are separated by commas The first field starts with an R if the system is ready to tare or else an NR The R must be present to tare the transducers The...

Page 134: ...nge bypassed inactive Remarks Before the molbox RFM can be tared the TARESETUP command must be used to configure the internal RPT connections properly After the tare operation is complete the TARESETUP command must again be used to restore the RFM to normal operation The ABORT command can also return operation to normal The normal order of remote commands for a tare operation TARESETUP UP or TARES...

Page 135: ...so manually set the tare value s using the TARESET tare command All pressure values are always in Pascal Pa While the tare cycle is executing a b busy will appear in the third character position of the FR and the SR command replies NOTE This command typically takes 5 to 7 seconds to complete if performing a tare no arguments given Example Command Reply Reply TARESET 66 Pa 66 Pa 7 Pa microrange opt...

Page 136: ...ired to use a shorter period than specified The reply to a TOTAL query provides the current total and the elapsed time period in the HH MM SS format The cycle is complete when the total flow is preceded by R Ready If the unit is actively totalizing an NR Not Ready proceeds the total flow Example Command Reply TOTAL 00 10 00 NR 0 0000 ucc 00 00 00 new cycle has started Command Reply Reply TOTAL NR ...

Page 137: ...e user flow measurement adjustment Syntax USERCAL adder mult USERCAL Defaults USERCAL 0 1 Arguments adder The flow adder in the current flow unit and gas type 0 to FS Mult The flow multiplier 0 1 to 2 Remarks The user definable adjustment lets the user modify the measured flow The adder and multiplier are separated by a comma The adder is in the current flow unit Example Command Reply USERCAL 58 9...

Page 138: ... lh m3m m3h cfm and cfh require pressure and a temperature conditions to be specified by the user Example Command Reply VLM 200 200 00 kPaa molbloc temp will be used Command Reply VLM 200 15 200 00 kPaa 15 C user defined temp will be used Errors ERR 6 One of the arguments is invalid See Also 3 2 3 3 2 3 1 and 3 2 3 4 FUNIT ZOFFSET HI and ZOFFSET LO Purpose Read or set the AutoZ pressure offset Pof...

Page 139: ... channels and to enable the events and event transitions Bit15 of all of these registers is not used because Bit15 represents a sign bit on some computer systems 4 4 1 STATUS REPORTING SYSTEM The molbox RFM status reporting system is used to track and report system status and errors The status subsystem is layered under and reports to the status reporting system It follows the model of the IEEE St...

Page 140: ...ignated bit to cause a SRQ except for the RQS MSS bit s which cannot cause a SRQ If you set this register to 20 14 hex an SRQ will occur if the MAV or the ERROR bit are set The description of these bits are given as OPER OPERational event register summary bit Bit 7 This bit is not supported by the molbox RFM RQS Requested Service Bit 6 Indicates that the SRQ line of the IEEE 488 interface has been...

Page 141: ... these bits are given as PON Power On Bit 7 Indicates that the molbox RFM power has been cycled since the last time this bit was read or cleared URQ User Request Bit 6 Indicates that the molbox RFM was set to local operation manually from the front panel by the user pressing the ESC key Command Error Bit 5 Indicates that a remote command error has occurred A command error is typically a syntax err...

Page 142: ...molbox RFM OPERATION AND MAINTENANCE MANUAL 1998 2007 DH Instruments a Fluke Company Page 132 N NO OT TE ES S ...

Page 143: ...sts associated with maintaining the flow standards needed to calibrate molblocs most users return their molblocs to a DHI Calibration Service rather than supporting the calibrations themselves molbloc calibration is not covered in this manual CalTool for molblocs software is available for facilities desiring to perform molbloc calibrations Contact your DHI representative for additional information...

Page 144: ...ol software to assist in the calibration of the molbox RFM The latest version of this software is always available for download free of charge from www dhinstruments com CalTool for RPTs steps the operator through the complete reference transducer calibration procedure It is capable of applying the necessary test pressures gathering the data calculating the optimum calibration coefficeints evaluat...

Page 145: ...ctively for all RPTs This does NOT mean that the molbox RFM has NOT been calibrated For the original factory calibration privileged factory coefficients are used for calibration adjustment This allows a new molbox RFM to be delivered with virgin calibration coefficients of PA 0 and PM 1 5 2 2 EQUIPMENT REQUIRED 5 2 2 1 UPSTREAM AND DOWNSTREAM ABSOLUTE RPTS Gas operated pressure standard with the f...

Page 146: ...prepare the molbox RFM for calibration of its upstream and downstream absolute RPTs n Set the molbox RFM on a stable surface near the calibration standard at a height as close as possible to the calibration standard s reference height Consider the connections that need to be made to the molbox RFM rear panel pressure quick connectors and access to the front panel display and keypad o Connect the c...

Page 147: ...of the RPT is vented The accessory stems do not have shut off valves The quick connector stems on the molbox to molbloc tubes also have shut off valves so they are closed when not connected 5 2 4 VIEWING AND EDITING RPT READINGS AND CALIBRATION INFORMATION Editing RPT calibration information will affect molbox RFM pressure measurements and can cause out of tolerance flow measurements RPT calibrati...

Page 148: ...tream absolute RPT reading is on the left and the downstream absolute reading is on the right If the AutoZ function is turned on the AutoZ correction is applied to these pressure values and the z indicators are present as shown above see Section 3 4 4 4 If AutoZ is off the correction is not applied and the indicators are not present The values displayed are the readings for the RPTs with the curre...

Page 149: ...on Closed 3 Bypass Open 4 Mirorange Bypass Open Figure 14 molbox RFM Internal Pneumatic Schematic RUN UPSTREAM OR DOWNSTREAM ABSOLUTE RPT CALIBRATION 1 High Isolation Open 2 Low Isolation Open 3 Bypass Closed 4 Mirorange Bypass Closed Figure 15 molbox RFM Internal Pneumatic Schematic RUN MICRORANGE DIFFERENTIAL RPT CALIBRATION ...

Page 150: ... or 3edit to make changes to calibration information The display is 1 Current adder always in Pascal Pa This is an edit field if 3edit was selected 2 Indication of which RPT calibration information is being viewed edited 3 Current multiplier dimensionless This is an edit field if 3edit was selected PA 0 0 dwnstrm RPT PM 1 00000 If 3edit was selected edit the values of PA and PM as desired Pressing...

Page 151: ...rding the pressure applied by the standard and the molbox RFM RPT s reading s at each calibration point The standard calibration range for the upstream and downstream absolute RPTs is 70 to 550 kPa absolute 10 to 80 psia The standard calibration range for the microrange differential RPT is 0 to 12 5 kPa 0 to 1 8 psi Dwell at least 30 seconds after setting the reference pressure at each point to al...

Page 152: ... stability of 0 0025 for one year 0 005 for three years The self calibration feature and the very high accuracy and stability of the reference resistors relative to the accuracy tolerance on the molbox RFM temperature measurements make it unnecessary to calibrate the ohmic measurement system independently It is a good practice however to verify the ohmic measurement system This is most easily acco...

Page 153: ...ation failed Possible reasons for failure include Faulty molbox RFM internal reference resistor s Faulty molbox RFM internal relays Faulty connections between molbox RFM and the molbloc simulator Faulty molbloc simulator Check the molbox RFM to molbloc simulator connections and repeat the verification If the out of tolerance condition persists the molbox RFM and or the molbloc simulator need servi...

Page 154: ...ized Service Provider for additional information on the molbloc EEPROM loading tool and obtaining molbloc data files 5 6 OVERHAUL If calibration of the Reference Pressure Transducers RPTs is included as part of the overhaul procedure the calibration procedure should be performed last as other overhaul procedures may affect RPT calibration Any or all of the following items may be included as part o...

Page 155: ...ucer RPT 3 Downstream LO absolute reference pressure transducer RPT 4 Optional microrange differential reference pressure transducer RPT not present if microrange option not included see Section 3 1 5 5 Display 6 Power supply 7 Micro board 8 Main board not visible under micro board and power supply 9 Cooling fan not visible mounted on top cover Figure 16 molbox RFM Internal View ...

Page 156: ...ection 5 6 1 8 5 6 1 4 DISPLAY 2 x 20 vacuum fluorescent alpha numeric display mounted to front panel 5 6 1 5 POWER SUPPLY molbox RFM has one power supply with two voltage outputs V DC 5 0 9 Amps for valve excitation RPT supply and analog circuit V DC 5 2 5 Amps for micro board main board display and fan 5 6 1 6 MICRO BOARD The micro board supports a Motorola 68302 micro controller EPROM EEPROM 12...

Page 157: ...ly Schematic 5 6 1 8 MAIN BOARD The main board is controlled by the micro board see Section 5 6 1 6 The main board supports the 12 V drivers for the valving assembly solenoid excitation the ohmic measurement system and the beeper The main board also includes COM ports for reading RPTs 5 6 1 9 COOLING FAN The cooling fan is mounted to the molbox RFM top cover and connected to the main board It is a...

Page 158: ...molbox RFM OPERATION AND MAINTENANCE MANUAL 1998 2007 DH Instruments a Fluke Company Page 148 N NO OT TE ES S ...

Page 159: ...l or consult system manager 3 6 2 Cannot establish communication over remote interface Computer and or molbox RFM interface not correctly configured incorrect or bad interface cable Check and correct interface configurations and cables if necessary Run COM port test 3 6 6 3 molbox RFM unable to read molbloc Cable not connected molbloc data corrupted Check cable connections try another molbloc relo...

Page 160: ...y criterion or stabilize flow 3 5 5 3 1 3 Ready indication does not seem to be based on current stability setting The flow is within the stability limit but the Reynolds number of the flow exceeds the maximum acceptable limit of 1 200 Operation is normal 3 5 5 3 1 3 Flow indication is flashing during molbloc L operation Reynolds number is greater than 1300 Operation is normal Indicates that flow i...

Page 161: ...pressure flow to be inside of limits 1 2 4 and 3 4 5 Flow indication appears to be incorrect Flow through molbloc is in wrong direction Check that flow through molbloc is in direction of arrow on molbloc Switch if necessary Flow indication appears to be incorrect Leak in pressure lines from molbloc to molbox RFM Check lines for leaks and correct if necessary 3 4 4 3 Flow indication appears to be i...

Page 162: ...nd you are using AVERAGING function Averaging period is wrong and does not correspond to reading period of the device you are comparing with Adjust averaging period and or be sure to synchronize averaging period of the molbox RFM and the device you are comparing to 3 4 6 2 Flow indication is negative Flow in your system is reverse from what you expect molbloc upstream and downstream pressure lines...

Page 163: ...y instability and sudden small jumps in flow rate The molbox RFM pneumatic circuit is contaminated with liquids Purge and clean molbox RFM and associated pneumatic systems Contact your DHI Authorized Service Provider Grossly inaccurate flow measurements and little or no response to pressure or flow changes RPT s destroyed by overpressure View pressure readings using P T If readings are grossly ina...

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Page 165: ... other units 7 1 1 PRESSURE Table 26 Pressure Unit Conversions TO CONVERT FROM PA TO MULTIPLY BY Pa Pascal 1 0 mbar millibar 1 0 E 02 kPa kilo Pascal 1 0 E 03 bar bar 1 0 E 05 mmWa 4 C millimeter of water 1 019716 E 01 mmHg 0 C millimeter of mercury 7 50063 E 03 psi pound per square inch 1 450377 E 04 psf pound per square foot 1 007206 E 06 inWa 4 C inch of water 4 014649 E 03 inWa 20 C inch of wa...

Page 166: ...ne C2H6 4 42602 E 07 Ethylene C2H4 4 75813 E 07 Fluoroform CHF3 1 90128 E 07 Helium He 3 36210 E 08 Hexafluoroethane C2F6 9 60432 E 06 Hydrogen H2 6 67483 E 08 Methane CH4 8 36354 E 07 Nitrogen N2 4 79808 E 07 Nitrous Oxide N2O 3 03321 E 07 Oxygen O2 4 19903 E 07 Propane C3H8 2 98516 E 07 Sulfur Hexafluoride SF6 9 06602 E 06 Xenon Xe 1 01710 E 07 Table 29 Conversions From sccm At 0 C To Other Volu...

Page 167: ...nt compressibility factors Table 31 Conversions From kg s To mole s For Various Gases TO CONVERT KG SEC TO MOLE S MULTIPLY BY Air Air 3 45316 E 01 Argon Ar 2 50325 E 01 Butane C4H10 1 72049 E 01 Carbon Dioxide CO2 2 27221 E 01 Carbon Monoxide CO 3 57015 E 01 Carbon Tetrafluoride CF4 1 13624 E 01 Ethane C2H6 3 32568 E 01 Ethylene C2H4 3 56455 E 01 Fluoroform CHF3 1 42837 E 01 Helium He 2 49838 E 02...

Page 168: ...ard E12 96 which specified that this definition be used for volumetrically base mass flow units Table 33 Conversion From sccm At 0 C to Volume Flow Units At Another Pressure And Temperature TO CONVERT FROM A VOLUMETRIC MASS FLOW UNIT TO THE EQUIVALENT VOLUME FLOW UNIT AT TEMPERATURE θ AND PUSER MULTIPLY BY sccm to ccm slm to lm slh to lh scfm to cfm scfh to cfh sm3m to m3m sm3h to m3h T Z P T Z Pu...

Page 169: ...ised of the possibility thereof and regardless of whether such products are used individually or as components in other products Items returned to DHI under warranty claim but determined to not have a defect covered under warranty or to not have a defect at all are subject to an evaluation and shipping charge as well as applicable repair and or calibration costs The provisions of this warranty and...

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Page 171: ...pe of the measured flow Freeze A DISPLAY function in which the current flow reading can be captured and displayed by pressing ENTER Full Mod Calibration A molbloc calibration option which is valid over a range of operating pressure FS Abbreviation of full scale The full scale value is the maximum value or the span of a measurement range Limits and specifications are often expressed as FS Gauge As ...

Page 172: ... when the process gas cannot be used for safety or cost reasons Target The value from which deviations are measured in the DEVIATION DISPLAY function Test Gas The gas flowing through the molbloc that is being used to run the test or calibration The test gas from the standpoint of the device under test could be a surrogate gas or the process gas Totalize A DISPLAY function in which the total mass o...

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