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Ludlum Measurements 334A, Руководство по эксплуатации

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Model 334A Operations Manual 

Ludlum Measurements, Inc 

16 

January 2021 

 

After the calibration has completed, it will report the efficiency. Typical 4pi efficiency is 20-

30% for Am-241.  If the efficiency falls outside these parameters, either

 Repeat Calibration

 or 

call a Ludlum Technician for assistance.   

If the efficiency is acceptable, remove the source from the detector, place the filter back, and 
close up the detector head.  Tap 

OK 

to close the dialog and save the new efficiency setting.  

Automatic Alpha Calibration 

Customers  should  first  perform  the  Advanced  Calibrations,  using  the  same  calibration 
isotope source, before running Automatic calibrations. 

The automatic alpha energy calibration is designed to make regular alpha energy calibration quick, 
easy, and accurate.  This calibration mode will adjust the offset parameter in the MCA and the 

energy channels of the radon isotopes to compensate for a shift of the spectrum due to electronic 
drift over time, or from significant temperature and pressure changes. 

To start the Automatic calibration tap 

Calibrate—Automatic Alpha…

 

on the menu. Open up the 

detector head and remove the filter.  Insert the source defined as the “Alpha Source” and tap 

Start Calibration.  

 The calibration routine will calculate the alpha efficiency and display the efficiency results.  The 

Alpha 4-Pi Efficiency should be 20-30 %.  An efficiency percent outside of the expected range 
would indicate a discrepancy in the process or possibly with the unit.  

Repeat Efficiency

 or call a 

Ludlum Technician for assistance.  Hit 

Next

 to go to the Calibrate Energy step.  

Содержание 334A

Страница 1: ...LUDLUM MODEL 334A ALPHA AIR MONITOR January 2021 ...

Страница 2: ......

Страница 3: ...Model 334A Operations Manual ...

Страница 4: ...cumentation may contain technical or other inaccuracies or typographical errors Ludlum reserves the right to make changes without prior notice No part of this publication may be copied without the express written permission of Ludlum Measurements Inc 501 Oak Street Sweetwater Texas 79556 Trademarks Ludlum the Ludlum logo and Model 334A are trademarks of Ludlum Measurements Inc Microsoft Windows CE...

Страница 5: ......

Страница 6: ...anty of merchantability or fitness which extend beyond the description of the face there of If the product does not perform as warranted herein purchaser s sole remedy shall be repair or replacement at the option of Ludlum Measurements In no event will Ludlum Measurements be liable for damages lost revenue lost wages or any other incidental or consequential damages arising from the purchase use or...

Страница 7: ......

Страница 8: ...IBRATION EXPIRATION 10 SOURCE REQUIREMENTS 10 SET SOURCE PARAMETERS 11 Calibration Instructions 11 ALPHA ENERGY CALIBRATION 11 Performing the Calibration 13 ALPHA EFFICIENCY CALIBRATION 15 AUTOMATIC ALPHA CALIBRATION 16 Response Check 17 FLOW CALIBRATION 18 Setting Up the Apparatus 18 Performing the Calibration 19 CONFIGURATION 21 INSTRUMENT PROPERTIES 21 INSTRUMENT OPTIONS 22 General Tab 23 Loggi...

Страница 9: ...MOVING WINDOWS 35 ALPHA MEASUREMENT CALCULATIONS 35 MINIMUM DETECTABLE MEASUREMENT CALCULATIONS 37 RADON MODE CONSIDERATIONS 39 RETRIEVING ANALYZING THE DATA 40 ENDING A DOSE MEASUREMENT 40 PC SYNCING SOFTWARE 40 CONNECTING TO A PC 41 SYNCING LOG FILES 42 GRAPHING DATA IN EXCEL MANUALLY 43 GRAPHING DATA IN EXCEL WITH TEMPLATES 43 Spectrum Chart 44 Chronic Acute Charts 45 RADNET OPERATION 46 ASCII ...

Страница 10: ...hat displays information on instrument status and readings during operation The estimated dose of the isotope s of interest and instrument status is displayed at all times A window below may be switched from showing historical readings and battery status or to display the current spectrum Unpacking and Repacking Remove the calibration certificate and place it in a secure location Remove the instru...

Страница 11: ...s an alarm acknowledge to silence and clear an alarm On the right side below the detector head there is a red power button mini USB port charging port and LED charging indicator along with other ports needed for additional options The Model 334A includes an annunciator alarm light audible alarm that is used when radiological alarms have been enabled The annunciator has an adjustable volume setting...

Страница 12: ...touched The filter holder suctions a 37mm filter in place and mounts inside the cavity opposite the detector face Between the detector face and the filter is a small gap of air that creates a flow path by extending circularly around the outside of the Detector Head Air borne particulates are suctioned into the Detector Head via the air flow path through the radial gap and are captured on the filte...

Страница 13: ...d once power is returned to the unit So after the battery is fully discharged all that is needed is to reconnect the unit to AC power and allow the battery to charge again Depending on user settings measurement records can either be stored on the SD card or on the My Documents folder The default save location for log data is the My Documents folder but in the event of a full battery discharge thes...

Страница 14: ...applications or changing display or network settings To close the Model 334A program tap File Close in the menu Response Check The Response Check dialog is the first screen to be displayed after starting the Model 334A program The Response Check function will be covered later in this manual For now and until the Model 334A is fully calibrated tap the Skip button to bypass the Response Check or wai...

Страница 15: ... menu The spectrum is displayed as a bar graph made up of the detected counts Each count is assigned to one of 256 channels increasing in energy along the non visible X axis The Y axis is a non visible scale of counts that compresses to fit the entire spectrum in view The red line represents the mathematical peak fit curve that best matches the actual data After several hours three peaks will have...

Страница 16: ...trument configuration or calibration By default password security is turned off and all menus and functions are accessible Password security may be enabled by checking Use Password Security from the File Properties menu The Properties dialog is explained fully in Section 3 Configuration Tap File Login from the menu to enter a password Security Levels and Default Passwords Logged Out User level all...

Страница 17: ...is configured with a real time clock which can be manually set or set automatically when connected via the USB port to a PC The unit is factory calibrated to the correct customer time zone before shipment Whenever the battery and external power are disconnected from the main processor board during maintenance or repair the clock will be reset to a default date The Model 334A program will sense thi...

Страница 18: ...n functions are accessed from the Calibration item on the main menu Two types of calibrations can be performed on the Model 334A The first is called the Automatic Alpha calibration which is a source calibration check The other type of calibration is the Advanced calibration which separates Alpha Energy and Alpha Efficiency calibrations Advanced Calibrations should be performed in this order Alpha ...

Страница 19: ...ror percentage Calibration Expiration The Model 334A program keeps track of the last time the alpha energy calibration was performed and will indicate that the unit is out of service if one of two conditions is met A user defined number of days since the last calibration have elapsed Default is 365 days The unit has exceeded the user defined number of hours of run time since the last calibration D...

Страница 20: ...ate Advanced Alpha Energy on the menu The Alpha Energy Calibration dialog will be displayed showing the alpha energy calibration settings and a window where the spectrum will appear with several red lines The horizontal axis represents the possible energies assigned to channels 0 to 255 The vertical scale accumulates counts in each channel and adjusts automatically to display the highest peak Seve...

Страница 21: ...fting to the next Scale will bring the peaks back into view on the spectrum Also as Gain is increased the noise amplitude will increase proportionally requiring a compensating increase in Threshold level Gain should not normally be changed from the factory setting Threshold Range 1 to 31 This value controls the amplitude threshold that pulses must exceed to be measured It should be set just above ...

Страница 22: ...have a marker In radon mode a peak marker will also appear for Po210 The energy of the Po210 peak is at 5 3 MeV left of the Po218 peak Roughing in the Source Peak If any of the configuration settings are drastically changed it helps to perform this step to reset them and get the radon peaks to appear in the correct location Place a mid energy alpha source such as Am 241 in the sampling head and ve...

Страница 23: ...e number of counts per channel Release the line on the channel with the highest counts Calibrating the Isotope of Interest The isotope s of interest also needs to be energy calibrated at this point Remove the filter and leave the detector exposed Using an appropriate source holder to provide repeatable geometry place the desired isotope of interest calibration source in the detector recess so that...

Страница 24: ...ficiency Calibration is used to determine the detector counting efficiency to the isotope of interest energy This efficiency is used to produce accurate exposure and concentrations in units of measure meaningful to the user e g DAC h and mWL It also makes sure that the Model 334A is counting at an acceptable rate To begin the Alpha Efficiency Calibration select Calibrate Advanced Alpha Efficiency ...

Страница 25: ...ion is designed to make regular alpha energy calibration quick easy and accurate This calibration mode will adjust the offset parameter in the MCA and the energy channels of the radon isotopes to compensate for a shift of the spectrum due to electronic drift over time or from significant temperature and pressure changes To start the Automatic calibration tap Calibrate Automatic Alpha on the menu O...

Страница 26: ...f you elect to save the new settings then the offset radon peaks and second IoI peak will be adjusted an equal amount to compensate for the new attenuation For most users doing a re calibration using the same isotopes these Automatic Alpha steps will be sufficient to calibrate the instrument Instruments that exhibit POOR_FIT status or erratic readings should be recalibrated using the advanced cali...

Страница 27: ...propriate equipment for the procedure Volumetric Digital Flowmeter a Rotameter will work as well Tygon tubing Flow restriction device a clamp or needle valve Flow Calibration Aid included with Model 334A 1 per order Create the testing apparatus by attaching the flow restriction device to the Tygon tubing on the side of the digital flowmeter opposite the unit and attaching the flow calibration aid ...

Страница 28: ... and reports the measured difference in an error percentage The flow calibration dialog instructs the user throughout the process NOTE Any flow rate will work as long as the measured flow entered is the same as what is reported by the flowmeter So if the Flowmeter reports 4 11 then the Measured Flow is entered at 4 11 even if the instructions ask for 4 0 LPM The first step in the flow calibration ...

Страница 29: ... the Measured Flow and then tap Validate The validation step will check to make sure the formula calculated by interpolation is correct and will produce an error percentage which should be less than 5 percent and is usually less than 1 percent The flow calibration is now completed and this example shows 0 4 error which is acceptable Tap Close and save the calibration settings Remove the flow calib...

Страница 30: ...s are accessed through the File and Monitor menus Each dialog and its settings are described below Instrument Properties This dialog controls the operation of the of the user interface aspects of the program Tap the File Properties menu item to access the Instrument Properties dialog Voice Update Frequency Voice output is not implemented in the Model 334A so the settings are disabled SECTION 3 ...

Страница 31: ... menu selection When unchecked alarms may be silenced either from the menu or by pressing the Alarm Ack button on the face of the Model 334A When paired with the Use Password Security option the user must have at least a config level password in order to acknowledge and silence the alarm Default is unchecked The Disable buttons when logged out setting prevents the use of all three front panel butt...

Страница 32: ...ieve a desired alarm level and response time Default is 120 Seconds Chronic Window This setting define the count time used to determine the Chronic Dose Concentration NetCps and Activity Longer times provide better sensitivity and lengthen the dose integration time Default is 240 Minutes Calibration Expiration Settings Calibration expires This non editable item displays the latest date on which th...

Страница 33: ...snapshots are written to a log file SpectrumYYYYMMDD txt If the setting is checked the Log Spectrums frequency field will be enabled Default is Spectrum Logging is ON Log Spectrums every This setting defines the frequency in minutes that spectrums are time stamped and logged Default is 10 Minutes Log data destination This selection defines the location where Model 334A data will be saved My Docume...

Страница 34: ... the selected isotope of interest is expected by the peak fit algorithm Although it is not editable from this dialog page it is set during the calibration procedure DAC Constant This setting defines the conversion constant to convert from Pico Curies per liter to DAC defined by 10CFR835 Note that the constant uses units of Pico Curies per liter to avoid the need for scientific notation Default is ...

Страница 35: ...gure the alarm limits for the isotope of interest See the dialog description under Alarm Settings below Iso 2 Tab This page defines the parameters concerning the second isotope of interest measurements By default the isotope of interest is none however this isotope may be changed to support the measurement of other alpha emitting isotopes ...

Страница 36: ...ute Alarms Dose DAC h This setting determines the alarm set point for an acute dose alarm Default is 80 DAC h Acceptable False Alarm Rate This setting defines the acceptable number of false alarms per year The limit has an effect on the calculated minimum detectable dose and concentration limits Therefore it has an effect on the dose and concentration sensitivities The setting is used to determine...

Страница 37: ... per minute above which the Model 334A will indicate a HI FLOW status A high flow status can indicate a missing filter leaking or disconnected vacuum line To achieve a missing filter limit remove the filter replace the filter holder check the flow rate and set just below this rate Default is 7 5 LPM Low Fail Limit This setting defines the limit in liters per minute below which the Model 334A will ...

Страница 38: ...e choices are Chronic and Acute data Chronic Only and Acute Only Default is Chronic and Acute and is factory set to user specifications Broadcast Spectrums This checkbox enables or disables the transmission of Model 334A spectrums to RadNet clients Check the box to enable spectrum broadcasts Spectrum Type List Box This list describes the options for spectrum packet broadcasts Allowable choices are...

Страница 39: ...otocol Default is checked if ordered COM This field specifies the Communications Port number of the PC that the RS 232 cable is connected to Default is COM5 Baud This field specifies the bits per second with which ASCII packets are broadcast Default is 19200 WiFi Enabled When checked this setting transmits measurement packets wirelessly using the ASCII Protocol Default is checked if ordered TCP Th...

Страница 40: ...n activity The detector and MCA are functioning properly The source isotope is correctly identified the peak area properly measured and that the alpha efficiency has not changed Source Requirements In source checks the source used should have an active plated diameter of at least 25mm 1 inch If the active area is larger the activity of the 25mm area must be known so that when masked to that size t...

Страница 41: ...ould set this value to be approximately the source activity in dpm minus 10 Count Time sec This setting defines the time window in seconds over which the activity will be averaged The actual duration of the Response Check will be longer to account for stabilization of the reading Set the High Low Limits to reflect the desired tolerance and set the Count Time to produce a reading that will reliably...

Страница 42: ...il the Acute and Chronic Window times have elapsed defaulted to 120sec and 240min respectively Until the full window times have elapsed the Model 334A is using incomplete spectrum accumulations to calculate the dose and concentration and has elevated statistical fluctuations of the results This means that for the first 240 seconds using twice the default Acute Window time the Acute MDD will be ele...

Страница 43: ...tries Return to the log entry view by tapping View Log In the event that a dose or concentration reading exceeds alarm limits the Model 334A will alarm visually and audibly automatically display the channel of the chronic or acute reading that caused the alarm and the status will be changed to High Alarm Operational Duration For lengthy or continuous air monitoring it is recommended that the unit ...

Страница 44: ...ast minute and also the minute previous are calculated For long lived isotopes the increase in net count rates over the two intervals is proportional to the concentration The Acute window time offers a very quick response to measurement data sacrificing some accuracy in the process The Chronic window time provides a very accurate dose reading but must take place over a substantial period of time A...

Страница 45: ...ration Calculation The concentration equation used for the acute and chronic alpha calculation is Eff Cal K Vol Yield Net T Net Net ion Concentrat DAC Sample W A 0 0 1 Where TWA Actual window time in seconds Net0 Net counts T 2TWA to T TWA Net1 Net counts T TWA to T Cal Calibration constant Eff Detector efficiency 4 Pi Yield Isotope Alpha yield VolSample Air volume since filter change KDAC DAC con...

Страница 46: ...Sample Flow rate KDAC DAC conversion factor equals one if DAC not used Minimum Detectable Measurement Calculations Uncertainties in Peak Counts In most ROI based Alpha CAM s the minimum detectible concentration is based on the statistical uncertainty of the background counts that fall within the region in combination with the uncertainty of any counts in excess of the background In the Model 334A ...

Страница 47: ...ectability variance used is a combination of the fit variance with the previously saved zero counts variance 2 0 645 1 Variance VarZero K VarLD Where K is the Sigma Factor a multiplier based on the False Alarm setting and the number of alarm determinations per year Calculation of the Minimum Detectable Activity MDA Eff Cal T Var MDA W A LD Calculation of the Minimum Detectable Concentration MDC DA...

Страница 48: ...is shown as the default reading on the instrument i e PAEC C The PAEC is based on the individual radon decay product concentrations as measured off the filter The beta decay product Pb 214 is estimated from the concentrations of Po 218 and Po 214 before its contribution to the PAEC can be added The thoron contributions from Po 212 and Bi 212 are also included in the PAEC result and when Bi 212 is ...

Страница 49: ...le Close menu item The program will terminate and close any open log data files This should be unnecessary for continuous sampling mode operation Note that if password security is enabled the user will be required to log in before the File Close menu item will be accessible PC Syncing Software To access the data on the Model 334A the user must install ActiveSync software from Microsoft and then co...

Страница 50: ...ed the Model 334A will appear under Computer in the File Explorer Your computer may categorize it as a camera phone or portable device A dialog will automatically pop up that requests to establish a permanent partnership Click Set up your device and follow the process Be sure to disable all options except Files because we do not want tasks contacts and appointments to be shared between the PC to t...

Страница 51: ...es can then be opened imported into a spreadsheet or printed Each log file contains time stamps in the name of the file They are formatted with YYYY being the year MM being the month and DD being the day of the file creation Each file begins with a header line describing the individual fields Each subsequent entry in the log files is stamped with the time and date of its creation The list below de...

Страница 52: ...from Microsoft Excel Once the Model 334A log data has been retrieved you may disconnect the USB cable from the computer to the unit Disconnecting the USB cable will not affect the operation of the unit nor the files copied or synced Graphing Data in Excel Manually Data can be imported in Microsoft Excel and then manually graphed by following these instructions Alternatively the data can be graphed...

Страница 53: ...pectrum data Follow the instructions to refresh the template with new data from your unit Spectrum Animate Chart Click the Spectrum Data tab to view the raw data Click on any cell to begin To import new data select the Data menu tab and click Refresh not Refresh All Navigate to the folder where you synced or copied the log files to earlier Find the spectrum file labeled Spectrum_YYYYMMDD and impor...

Страница 54: ...esh from each tab and choose one file at a time Alpha Chronic Chart Alpha Acute Chart When formatting the Y axis the whole chart does not need to be in view as the minimum detectable line will likely be too high in the beginning to achieve good readability of the rest The chart is best read when the typical readings are within the bottom fifth of the chart See the example chart below for typical a...

Страница 55: ...oint WAP is required to receive the transmissions from the Model 334A and relay those transmissions either via an Ethernet cable or via a second wireless link to the RadNet Client workstation The concentration readings and spectrums from up to nine Model 334As may be linked to a single RadNet Client workstation Configuration Model 334As purchased with the RadNet Output Option come preconfigured fo...

Страница 56: ...iguration sheet on the Client LAN Side When connected log on with admin as the User No password is required In the event that the WAP no longer responds to the assigned address reset the WAP back to factory defaults by referring to its manual RadNet Client Workstation Configuration In order to communicate with the Model 334A and wireless access point the client workstation must be configured with ...

Страница 57: ...eless module and antenna for wirelessly broadcasting the ASCII log data A wireless access point WAP is required to receive the transmissions from the Model 334A and relay those transmissions either via an Ethernet cable to a network workstation or via a second wireless link to the workstation Configuration of RS 232 Connections The serial RS 232 port on the Model 334A is a 2 wire output only seria...

Страница 58: ...ollows Initializing 1 Normal 0 Standby 40 Alarm_High 18 Flow_Low 24 Flow_High 25 Fail_Det 32 Fail_Low_Batt 33 Fail_Int_Comm 34 Fail_Poor_Fit 36 Fail_Flow 37 Fail_Calib 38 Concen is the derived airborne concentration in units of DAC floating point MDC is the minimum detectable concentration in DAC floating point DAC h is the estimated worker dose in units of DAC h floating point MDD is the minimum ...

Страница 59: ...Concentration set point has been exceeded Low Flow Flow rate is below Low Limit High Flow Flow Rate is above High Limit Flow Fail Flow Rate is below Fail Limit Detector Fail No counts received from detector Low Batt Battery is almost expired MCA Fail No communications with Multi Channel Analyzer PCB Poor Fit Could not fit the spectrum with the defined isotopes Possible unknown isotope Out of Calib...

Страница 60: ...ith no load Alpha Data Analysis MCA 1024 channel analyzer binned to 256 channel spectrum Alpha Peak shape fitting algorithm Po 212 Po 214 Po 218 optional one or two isotopes of interest Acute fast response and Chronic high sensitivity dose determinations Typical 30 efficiency for Pu 239 Physical Battery powered 7 2V Lithium Ion 6 6Ah Weight 8 3 lbs 3 8 kg Dimensions W x H x D 10 x 12 x 5 in Temper...

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