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Optidew Series User’s Manual

97430 Issue 2, March 2017

INTRODUCTION

1.2 Optidew

Sensor

Optidew Series’ sensors are available with either single stage, or dual stage peltier

devices, and with a variety of different sensor body and mirror materials. The following

tables show the capabilities of each sensor type:

Single Stage

Dual Stage

Metal Body

Available sensor body materials

Acetal

PEEK

Aluminum

Stainless steel

Approximate maximum depression

55°C (99°F) 65°C (117°F)

45°C (81°F)

Equivalent % RH range

2 to 100%

0.5 to 100%

4 to 100%

Lowest Measureable Dew Point

Sensor temperature 20°C (68°F)

-30°C (-22°F) -40°C (-40°F)

-20°C

With additional cooling

-40°C (-40°F) -50°C (-58°F)

N/A

Table 1

Sensor Capabilities

Acetal

PEEK

Stainless Steel

Aluminum

Maximum Temperature

+90°C (+194°F)

+130°C (+266°F)

Table 2

Sensor Body Materials

All sensor variants are available in high pressure versions, able to operate in pressure

up to 250 barg (3600 psig).

Summary of Contents for Optidew

Page 1: ...2017 Power On Po wer Inpu t 85 254 Va c 47 440 Hz Communications Port Status Temperature Probe Output Connec tions Dew point Sen sor Warning Disconnect power supply before removing cover OPTIDEW High Performance Optical Dew point Transmitter Display Control Alarm Dcc OPTIDEW VISION Precision Dewpointmeter ...

Page 2: ...information when contacting Michell Instruments for service purposes Instrument Code Serial Number Invoice Date Location of Instrument Tag No Instrument Code Serial Number Invoice Date Location of Instrument Tag No Instrument Code Serial Number Invoice Date Location of Instrument Tag No ...

Page 3: ...may not be copied or otherwise reproduced communicated in any way to third parties nor stored in any Data Processing System without the express written authorization of Michell Instruments Ltd Optidew Optidew Vision For Michell Instruments contact information please go to www michell com ...

Page 4: ...llation 11 2 5 1 Integral Sensor Configuration 12 2 6 Remote Temperature Probe 12 3 OPERATION 13 3 1 Display 13 3 2 LOCAL and REMOTE modes 13 3 2 1 Screens 14 3 3 Operational Functions 15 3 3 1 Operating Principle 15 3 3 2 Operating Cycle 15 3 3 3 DCC 16 3 3 4 DATA HOLD Phase 16 3 3 5 MAXCOOL 17 3 3 6 FAST Frost Assurance System Technology 17 3 3 7 Mirror Condition and Peltier Power 18 3 4 Optisof...

Page 5: ...on Window 26 Figure 12 Change Password Window 26 Figure 13 Sensor Mirror Cleaning 31 Appendices Appendix A Technical Specification 34 Appendix B Optidew RS232 Commands 37 Appendix C Troubleshooting Common Faults 41 Appendix D Dimensional Drawings 47 D 1 Optidew 47 D 2 Optidew Integral Version 48 D 3 Optidew Vision 49 D 4 Sensor and Probe Dimensions 50 Appendix E Quality Recycling Warranty Informat...

Page 6: ...e specified safe working pressure is 20 barg 300 psig The pressure rated versions can withstand 250 barg 3600 psig Toxic Materials The use of hazardous materials in the construction of this instrument has been minimized During normal operation it is not possible for the user to come into contact with any hazardous substance which might be employed in the construction of the instrument Care should ...

Page 7: ...hnical Commission LED Light Emitting Diode m meter s mA milliampere Max maximum Min minimum mm millimeters m sec meters per second N C not connected normally closed relay contacts N O normally open relay contacts Nl min liters per minute percentage psig pounds per square inch gauge scfh standard cubic feet per hour RS232 serial data transmission standard RS485 serial data transmission standard T t...

Page 8: ...plied as standard with a fully traceable in house calibration or optional UKAS certified calibration Their simple operation makes it possible for anyone to use with minimum training Simply connect the instrument power it up and measurement will begin automatically Frost Assurance Technology FAST Super cooled water can exist at temperatures down to 30 C 22 F and when formed on the mirror of a chill...

Page 9: ...rs and sensor cable Figure 1 Optidew Figure 2 Optidew Vision The Optidew features a rugged 304 stainless steel industrial enclosure offering protection to IP66 NEMA 4x The enclosure is suitable for wall mounting and can be ordered either as a blind transmitter or with an optional display The Optidew Vision is a bench top model with integrated display ideal for laboratory use ...

Page 10: ...ble sensor body materials Acetal Acetal PEEK Aluminum Stainless steel Approximate maximum depression 55 C 99 F 65 C 117 F 45 C 81 F Equivalent RH range 2 to 100 0 5 to 100 4 to 100 Lowest Measureable Dew Point Sensor temperature 20 C 68 F 30 C 22 F 40 C 40 F 20 C With additional cooling 40 C 40 F 50 C 58 F N A Table 1 Sensor Capabilities Acetal PEEK Stainless Steel Aluminum Maximum Temperature 90 ...

Page 11: ...e analog and digital outputs Michell order code OPT WPS Optidew Vision The Optidew Vision is designed to be bench mounted and is supplied with a tilting carry handle but it can also be panel mounted using the optional panel mounting kit Michell order code OPV PMK 2 2 Instrument Connections Optidew Front Panel 1 OPTIDEW High Performance Optical Dew point Transmitter h 2 h Number Description 1 Displ...

Page 12: ...ollowed by resetting the mirror condition during a DCC cycle Refer to Section 5 for more details 3 Serial Connector For digital serial communications Refer to Section 2 4 4 Sensor Connector Used for connecting the Optidew sensor via the sensor cable 5 Mounting Point For integral sensor version 6 Power Connector Universal power input 90 to 264 V AC OR 127 to 370 V DC 47 to 440 Hz 7 Temperature Conn...

Page 13: ...nstrument is in DCC or DATA HOLD mode Flashes in the event of an Optics fault This normally means the mirror needs cleaning followed by resetting the mirror condition during a DCC cycle Refer to Section 5 for more details 2 Display Shows measured or calculated instrument parameters Refer to Section 3 1 3 Display Control Switches between different display screens and puts the instrument in REMOTE M...

Page 14: ...ype 2A Quick blow Glass 20 x 5mm 2 Mirror Condition Potentiometer Used to adjust mirror condition during a DCC cycle Refer to Section 3 3 7 3 Serial Connector For digital serial communications Refer to Section 2 4 4 Temperature Connector For connection of remote PT100 temperature probe 5 Sensor Connector Used for connecting the Optidew sensor via the sensor cable 6 Output Connector Two current out...

Page 15: ...ollows Pin Connection Conductor Color Pin 1 Live Line Voltage Brown Pin 2 N C N A Pin 3 Neutral Blue Ground Green Yellow NOTE The Optidew is designed for continuous operation and therefore does not feature a power on off switch As soon as power is applied the green power LED will illuminate and the transmitter will initiate a DCC cycle illuminating the system status LED The part number for a repla...

Page 16: ...cs Fault Alarm Relay COM 9 Optics Fault Alarm Relay N O 6 Optics Fault Alarm Relay N O 10 Optics Fault Alarm Relay COM 7 Channel 1 Current Output 11 Optics Fault Alarm Relay N C 8 Channel 1 Ground 12 Status Relay N O 9 Channel 2 Current Output 13 Status Relay COM 10 Channel 2 Ground 14 Status Relay N C 11 12 Screen 15 Not Connected 2 3 2 Current Outputs Two current source outputs are provided whic...

Page 17: ...llowed by resetting the mirror condition during a DCC cycle Refer to Section 5 for more details Refer to Section 2 3 for wiring details 2 4 Digital Communications Port The Optidew Series provides either RS232 or RS485 serial communications via a 9 way D type connector This allows for communication with a PC data logger or other hardware device The following communication settings are required Baud...

Page 18: ...eaning details 2 If the sensor is installed within a sealed gas system it must be fixed securely without any possibility of leaks Ensure that the sample flow across the sensor is correctly regulated 3 The gas connections for the remote sensor are either via a permanently installed sample port into which the remote sensor can be inserted or via a sensor block see Figure 3 immediately attached to th...

Page 19: ... be fitted directly to the bayonet type connector on the case of the instrument without using a sensor cable A retaining bracket provides support for the sensor NOTE This is not possible with the Optidew Vision Installation Removal 1 Connect the sensor to the bayonet type connector on the case of the Optidew 2 Fit the retaining bracket configuration drawing shown in Appendix D 1 3 Secure the retai...

Page 20: ...dew Vision features a front panel VFD When power is applied to the Optidew or Optidew Vision the display will momentarily show test characters after which the start up banner will be displayed for approximately 7 seconds 3 2 LOCAL and REMOTE modes To the right of the display is a multi function button Pressing the button in LOCAL mode scrolls through the available display screens Pressing and hold...

Page 21: ...een 2 Peltier Power and the Mirror Condition Refer to Section 3 3 7 Screen 3 RH and ambient temperature Screen 4 Dew point and ambient temperature Screen 5 Humidity in gkg 1 and ambient temperature Screen 6 Humidity in gm 3 and ambient temperature Screen 7 t tdp and ambient temperature This is the difference between ambient temperature and dew point NOTE This parameter will be equal to 0 if the de...

Page 22: ...poration rate and condensation rate at the surface of the mirror are equal the mirror temperature read by a Pt100 platinum resistance thermometer embedded in the mirror represents the dew point 3 3 2 Operating Cycle Figure 4 Operating Cycle At initial switch on the instrument enters a DCC cycle for 4 minutes This heats the mirror 20 C 36 F above the sensor temperature This ensures that all moistur...

Page 23: ...n about the operating cycle of the Optidew and DATA HOLD mode refer to Sections 3 4 2 and 3 4 4 3 3 4 DATA HOLD Phase During DATA HOLD the level of the Channel 1 mA output is held and the Status Relay and Status LED are energized and illuminated respectively until the system has stabilized onto the measured dew point The DATA HOLD phase will finish when the following two conditions are met The min...

Page 24: ...ing commands to the instrument using the digital communications port 3 3 6 FAST Frost Assurance System Technology Theoretically it is possible for water to exist as a super cooled liquid at temperatures down to 40 C 40 F A gas in equilibrium with ice is capable of supporting a greater quantity of water vapor at a given temperature than a gas in equilibrium with liquid water This means that a measu...

Page 25: ...t COOL indicates the system is depressing the heat pump in order to form dew on the mirror surface HEAT indicates a rapid increase in dew point level whereby the system needs to increase the temperature of the mirror surface to read this new dew point value The Mirror Condition indicates the amount of signal received back from the mirror which includes both the level of moisture and contamination ...

Page 26: ...l 1 mA output The ambient temperature is shown in the lower display NOTE The humidity display will blink if the dew point is higher than the temperature This is normal and not a fault 3 4 2 Mirror Condition Mirror Condition indicates the amount of signal received back from the mirror which includes both the level of moisture and contamination on the mirror surface In DCC mode this display will onl...

Page 27: ...OL The MAXCOOL indicator will illuminate to indicate the MAXCOOL function has been activated The system will drive the heat pump into maximum depression This feature can be used to ascertain if the measured dew point is within the measurement capability of the instrument NOTE It is necessary to manually deactivate the MAXCOOL function Refer to Section 3 3 5 for more details Alarm The alarm indicat...

Page 28: ...s not possible The pressure value is used to correct gm 3 and gkg 1 for atmospheric pressure By entering the atmospheric pressure the display and Channel 1 mA output if either gm 3 or gkg 1 is selected will both be corrected accordingly The Alarm can be set to OFF or set to be active on any of the process variables i e dew point ambient temperature temperature difference RH gm 3 or gkg 1 as shown ...

Page 29: ...ue while in these modes and chart the held data values accordingly To log the measured and calculated humidity values to a data file for further analysis click on the check box in the Logging section and specify a file name by clicking on the Browse button If a log file is not required simply uncheck the box To Run Pause and Stop the charting and logging facility use the chart control buttons acco...

Page 30: ...g on the Statistics button on the Virtual Hygrometer window will display the Basic statistics window as shown below This window shows the maximum minimum and average of each parameter since the program began taking readings from the instrument or since the Reset button was pressed Figure 9 Basic Statistics Window ...

Page 31: ...ment point from a known reference value Data provided on the Calibration Certificate is normally arranged as shown in the following extracts Extract from a UKAS Calibration Certificate Generated Dew point C Test Hygrometer Dew point Temperature C Sensor Temperature C Correction Required C Expanded Uncertainty C 39 89 40 11 20 0 22 0 26 20 10 20 31 0 0 21 0 22 0 39 0 20 21 0 19 0 18 Extract from a ...

Page 32: ...e entered DP Ref Dew point data for the reference hygrometer sometimes called the actual dew point or the standard DP Reading Measured dew point value of the Optidew under test Temp Ref Temperature data from the reference thermometer Temp Reading Measured temperature value of the Optidew under test Data can be entered for between 3 and 11 different dew point and temperature calibration points If n...

Page 33: ...y will indicate this fact To remove the Calibration Correction window de select the check box click on Apply then click on Close Figure 11 Calibration Correction Window NOTE Enter the calibration data in descending order so the highest values are in row 1 as shown above 3 4 9 Change of Password The initial password is Michell This can be changed after entering the Control and Calibration Data wind...

Page 34: ...e to water vapor as the water molecule is extremely small compared to the structure of solids even when compared to the crystalline structure of metals The graph above shows the dew point inside tubing of different materials when purged with very dry gas where the exterior of the tubing is in the ambient environment Many materials contain moisture as part of their structure particularly organic ma...

Page 35: ...ce the time it takes for the sample system to dry out when purged with dry gas Over a long tubing run water will inevitably migrate into any line and the effects of adsorption and desorption will become more apparent It is clear from the graph shown above that the best materials to resist transpiration are stainless steel and PTFE Trapped Moisture Dead volumes areas which are not in a direct flow ...

Page 36: ...e vapor pressure differential will also allow water vapor to contaminate the flow Flow Rates Theoretically flow rate has no direct effect on the measured moisture content but in practice it can have unanticipated effects on response speed and accuracy The optimal flow rate varies depending on the measurement technology and can always be found in the instrument or sensor manual An inadequate flow r...

Page 37: ...ments by having a cooling effect on the mirror This is most apparent with gases that have a high thermal conductivity such as hydrogen and helium POSSIBLE INJURY The tubing valves and other apparatus attached to this instrument must be adequate for the maximum pressure which will be applied otherwise physical injury to the operator or bystander is possible Before disconnecting the instrument from ...

Page 38: ...an the mirror surface and optics window with a cotton bud Q Tip soaked in distilled water If the sensor has been exposed to oil based contamination then use one of the following solvents methanol ethanol or isopropyl alcohol To avoid damage to the mirror surface do not press too firmly on the cotton bud Q Tip when cleaning Allow the cleaning solvent to fully evaporate 3 Reset the mirror condition ...

Page 39: ...n DCC for 4 minutes it is important that the adjustments are only made in this mode If the instrument comes out of DCC the status LED will no longer be illuminated just cycle power to the instrument 3 Observe the mirror condition on the display or the application software 4 Adjust the potentiometer until the mirror condition is 0 2 If the mirror condition shows LOW on the display or flashing 0 on ...

Page 40: ... output to the serial port gofth Continuously outputs signal mirror level between 0 and 1023 abc Starts a DCC cycle The instrument will now be in DCC for 4 minutes it is important that the adjustments are only made in this mode During this time adjust the potentiometer until the signal level is 150 10 If the instrument comes out of DCC the status LED will no longer be illuminated send the abc comm...

Page 41: ...Optidew Series User s Manual Michell Instruments 33 MAINTENANCE Appendix A Technical Specifications ...

Page 42: ...0 Cdp at sensor temperature of 130 C Temperature Range 40 to 90 C 40 to 194 F 40 to 90 C 40 to 194 F 40 to 130 C 40 to 266 F 40 to 130 C 40 to 266 F RH Range 2 to 100 0 5 to 100 0 5 to 100 10 to 100 Min Measured Dew Point 20 C 68 F 30 C 22 F 40 C 40 F 40 C 40 F 10 C 14 F Mirror Material Options Gold plated copper standard gold stud 316 stainless steel stud Platinum stud Sensor Body Material Option...

Page 43: ...tatus Operating Temperature 20 to 50 C 4 to 122 F ambient Environmental Conditions Up to 98 RH non condensing Optidew only 100 RH condensing with optional weatherproof cable pack Enclosure Optidew 304 stainless steel DIN 1 4301 Optidew Vision Standing case with carry handle Panel mounting kit optional Ingress Protection Optidew IP66 NEMA 4X Optidew Vision IP54 NEMA 2 rated Cable Pack Power and RS2...

Page 44: ...Optidew Series User s Manual 36 97430 Issue 2 March 2017 APPENDIX A Appendix B Optidew RS232 Commands ...

Page 45: ...ion cmdt sets unit for CMDT mode temperature measurement disabled opti sets unit for OPTIDEW temperature measurement enabled Measured and calculated parameters gdp returns dew point value gtp returns temperature value grh returns rh value gofth repeatedly outputs mirror signal level gclm returns clean mirror value y outputs status string refer to information on the following page x outputs status ...

Page 46: ...mp DP 5 Temp 6 OFF NOTE Some commands may not feature in all versions of the firmware Optidew Status String The measured values and status information can also be read as one string by entering the command y cr which will output the information in the following format 020702110975012405892116160897201 cr For continuous monitoring send x cr which outputs the status string continuously as soon as it...

Page 47: ...e the value is 0589 or 24 cooling NOTE The depression is shown on the Optidew Optidew Vision display and OptiSoft as a percentage and is calculated as follows If depression 450 peltier drive PeltierDrive 450 5 73 peltier is cooling If depression 450 peltier drive 449 PeltierDrive 4 49 peltier is heating If depression 0 peltier is neither heating nor cooling Character 22 represents the status of th...

Page 48: ...Optidew Series User s Manual 40 97430 Issue 2 March 2017 APPENDIX B Appendix C Troubleshooting Common Faults ...

Page 49: ...ARNING Do not attempt to disassemble the instrument or sensor This will invalidate the calibration and may cause permanent damage to the instrument voiding the warranty It is permitted to remove the lid of the Optidew for the purpose of adjusting the mirror condition potentiometer only The Optidew Vision must NOT be disassembled Symptom Cannot connect to HyperTerminal Optisoft Cause If unit has di...

Page 50: ...sor cable conductors i e Pin A Pin A continuity Resolution Ensure sensor cable connections are sound Source replacement sensor cable from local Michell Instruments representative Cause Heating transistor on instrument damaged Diagnosis Run a DCC cycle and run a MAXCOOL for a short period If temperature does not increase during DCC but does decrease during MAXCOOL then heating transistor on instrum...

Page 51: ...uminated while instrument is switched on Resolution Contact Michell Instruments Service department Symptom Fixed 0 or flashing 0 low Mirror Condition Constant cooling See below Cause LED too bright mirror condition not set correctly Resolution Set mirror condition during DCC cycle as per instruction in Section 5 Maintenance Ensure red sensor LED brightness changes as potentiometer is adjusted Caus...

Page 52: ...he sensor is sufficiently ventilated to remove build up of heat generated when the heat pump is cooling High ambient temperatures will limit the depression range of the sensor If the maximum depression is within the specification above then the dew point may be below the measurement capabilities of the sensor In this case contact Michell Instruments for further advice Cause Photo detector fault Di...

Page 53: ...a reliable recently calibrated reference there is likely a problem with the instrument Return to service department for service and calibration Symptom Dew point reading unstable Cause Mirror is dirty Resolution Clean mirror according to instructions in manual Set mirror condition during DCC cycle as per manual instructions Cause Problem with measurement technique Resolution Contact Michell Instru...

Page 54: ...Optidew Series User s Manual 46 97430 Issue 2 March 2017 APPENDIX D Appendix D Dimensional Drawings ...

Page 55: ...l Instruments 47 APPENDIX D Appendix D Dimensional Drawings D 1 Optidew 222mm 8 74 Wall Mounting Brackets 4 each Ø M8 OPTIDEW High Performance Optical Dew point Transmitter h h h h h h 164mm 6 46 89mm 3 54 h h h 200mm 7 87 h h 200mm 7 87 ...

Page 56: ...ch 2017 APPENDIX D D 2 Optidew Integral Version Bracket Retaining Nut 222mm 8 74 Wall Mounting Brackets 4 each Ø M8 OPTIDEW High Performance Optical Dew point Transmitter h h h h h h 164mm 6 46 89mm 3 54 h h 200mm 7 87 h h 200mm 7 87 h h 365mm 14 37 h ...

Page 57: ...PENDIX D D 3 Optidew Vision OVERALL DEPTH OVERALL WIDTH OPTIDEW VISION Precision Dewpointmeter Alarm Dcc Display Control h h 290mm 11 4 h h 260mm 10 2 h h MIN CABLE CLEARANCE h h 340mm 13 4 275mm 10 8 h h h h h h 85mm 3 3 100mm 3 9 250mm 9 8 h h 130mm 5 1 ...

Page 58: ... 5mm 0 14 With Sintered or HDPE Guard Optional Dowty Bonded Seal M36X1 5 6g Ø45mm 1 77 Ø28mm 1 10 61mm 2 40 1 Stage 63mm 2 48 2 Stage 126mm 4 96 1 Stage 128mm 5 04 2 Stage Sensor Overall Dimensions Ø3mm 0 11 j i g g g 76mm 2 99 70mm 2 76 g 37mm 1 46 Ø9 5mm 0 3 Ø4 5mm 0 17 Cable Diameter i i j j i j Ø6mm 0 23 g g Remote Temperature Probe Dimensions 63mm 2 48 61mm 2 40 h h h h Ø3mm 0 11 j i Ø18 5mm ...

Page 59: ...Optidew Series User s Manual Michell Instruments 51 APPENDIX E Appendix E Quality Recycling Warranty Information ...

Page 60: ... directives Full information can be found on our website at www michell com compliance This page contains information on the following directives ATEX Directive Calibration Facilities Confl ict Minerals FCC Statement Manufacturing Quality Modern Slavery Statement Pressure Equipment Directive REACH RoHS2 WEEE2 Recycling Policy Warranty and Returns This information is also available in PDF format ...

Page 61: ...Optidew Series User s Manual Michell Instruments 53 APPENDIX F Appendix F Return Document Decontamination Declaration ...

Page 62: ... chemicals YES NO Radioactive substances YES NO Other hazards YES NO Please provide details of any hazardous materials used with this equipment as indicated above use continuation sheet if necessary Your method of cleaning decontamination Has the equipment been cleaned and decontaminated YES NOT NECESSARY Michell Instruments will not accept instruments that have been exposed to toxins radio activi...

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Page 66: ...http www michell com ...

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