Fluke 35040 manual Effective Exposure Time Measurements, General Measurements, Specifications

Page 11

General Information

Specifications 1

1.0000 μA

0.0001 μA

Measurement Method: Average current measurement is derived by monitoring the charge integrated over the time interval beginning 1.33 seconds after the detection of the start of the exposure, and ending

1.33seconds prior to the detection of the end of the exposure. Dividing the charge integrated over this interval by duration of the time interval yields the average current value.

Measurement Accuracy: The accuracy of the average current value in %rdg is approximately equal to the accuracy of the integrated charge measurement value from which it is produced. This value may be calculated by converting the “counts” contribution to a %rdg and summing this value with the inherent 0.20%rdg base accuracy of the charge measurement. Since the average current measurements are based directly upon charge measurements, an independent current calibration is not required.

Measurement Noise: Average current measurement noise decreases as the integration time interval increases. Typically, the noise in the average current measurement after a 100 second integration interval will be 10 times less than is present in the current measurement.

Response Speed: The display of average current measurement values will begin within 4 seconds of the start of the exposure.

Effective Exposure Time Measurements

Range and Resolution:

 

Full Scale Range

Display Resolution

Seconds

 

Hours/Minutes/Seconds

 

 

59.99 s

 

59.99 s

0.01 s

 

 

 

 

19,999.9 s

 

5 h 33 min 19.9 s

0.1 s

 

 

 

 

Measurement Method: The effective exposure time value is calculated as the quotient of the charge and average current measurement values. A minimum exposure duration of 3.5 seconds is required to produce an effective exposure time measurement value.

Measurement Accuracy: Although the accuracy of the effective exposure time measurement value is directly dependent upon the accuracy of the internal oscillator frequency (better than ± 0.01%), more important to the achievable accuracy of this measurement are the effects of linearity and noise in the exposure and average current measurement values upon which it is based. In practice, an upper limit of the error in the exposure time value in %rdg will be equal to the %rdg noise observed in the average current display values.

Response Speed: The display of effective exposure time values will begin within 4 seconds of the start of the exposure.

General Measurements

Dose Conversion: Dose measurement values are calculated by forming the product of the measured charge, ion chamber calibration factor, and the air density correction factor.

Dose Rate Conversion: Dose Rate measurement values are calculated by forming the product of the measured current, ion chamber calibration factor, air density correction factor, and time unit multiplier.

Measurement Non-Linearity:The maximum variation from a straight line is ± 0.1% of range on all charge and current ranges.

Long Term Stability: Ultra high long-term stability on the order of 0.1% per 5 years for both charge and current measurements is expected. Long-term measurement stability is verified as a part of each factory recalibration using inputs of -1.90 nC and ± 19.0 nC for charge and 19.0 nA for current. Compliance to the warranted specifications is considered satisfied if the observed measurement errors (%rdg) meet the following equations:

1-5

Page 10 Page 12
Image 11
Page 10 Page 12
Contents Therapy Dosimeter 35040Fluke Biomedical Table of Contents Sample Customization Reports Troubleshooting and ServiceAddendum Features of Firmware Version 27JAN00 or Later Iii Blank Introduction FeaturesIntroduction Operators Manual Before You Start Safety PrecautionsSafety Symbols And Terms Manual Addenda SpecificationsFactory Calibration Error Source ± %rdg Maximum ErrorCurrent Measurements Full Scale Range Display Resolution Noise ± countsFull Scale Range Display Resolution Timed Charge MeasurementsGeneral Measurements SpecificationsEffective Exposure Time Measurements High Performance Power Supply and Battery Charger Unpacking and Inspection 35040 Functional Description Hardware Block Diagram of the Model 35040 Therapy DosimeterSerial Communications Port Power SupplyFront Panel MicroControllerMultiplexer and A/D Converter Basic Operating EquationsElectrometer Bias SupplyQAccumprevious Quantity Description Units CommentsQExposure QAccum= time of electrometer conversion s Charge and Current MeasurementsLeakage Measurements Timed Charge and Dose Exposure Charge and DoseExposure Current and Rate Setting ThresholdsPredicted Timed Charge and Dose Accumulated Charge and DoseDoseRate = I a × Iccf Units/C × Adcf × RateMultiplier s Exposure TimeMm Hg = inch Hg x Air Density Correction Factor⎝ P Units Display Minimum Maximum Standard Resolution ErrorIntroduction SetupSetup Front Panel FamiliarizationRear Panel Familiarization Powering The SystemIon Chamber Connector Power-Up Self-Test and Display MessagesMaking Non-Timed Exposure Measurements Basic Measurement TechniquesGeneral Considerations 3Making Timed Exposure Measurements Timer SetupTimer Use Using Other Ion Chambers Battery CareFront Panel Controls PowerBattery Care Operation InstructionsPowering Up the Model 35040 Therapy Dosimeter Operation Instructions Powering Down the Model 35040 Therapy DosimeterUsing the Test Function Button QScaleFactor=1.0000 IScaleFactor=1.0000 5Automatic Leakage Compensation 12. The Test Function Screen Showing the Timer SettingsCalibrated by Keithley RMD Nov 15 17. The Test Function Screen Showing the Timer Settings 6Timer SetupUsing the AIR Density Button Using the Detector Select ButtonUsing the Bias Select Button Using the Units Select ButtonSet 300.0 V 100% Central Electrde Pos IC Bias 300.0 V CEP Overranging Conditions Using the RESET/MEASURE ButtonCondition Values Overranged Reset ErrorOverrange Conditions Annunciator Condition Reset Error With Automatic Leakage Compensation EnabledAnnunciators AnnunciatorsCondition Overranged Measurement Measurement Indicators and ConditionsIndicator Measurement Condition ? left of valueStarting the Customization Software Installing/Uninstalling Customization SoftwareCustomization Connection to the ComputerCOM Port Drop Down List DownloadingMenu Items and Controls File Save AS and File Print Ion ChambersClose or File Close Edit Special Items OK and Cancel36. The Special Items Menu Calibration Temperature has focus Download and CancelMeasurement Displays Display Line Operators Manual Available Display LinesChanging a Line on a Display Using the APPEND, DELETE, and Insert ButtonsDisplay Line Group Selection Selecting an Item and Placing It38. The Timer Intervals Form Timer Intervals39. The Bias Settings Form Bias SettingsExamples Deleting a Display Changing the Pressure UnitsCustomizing a Measurement Display Appending a DisplayErrors Troubleshooting Troubleshooting and ServiceSymptom LoBias annunciator displayed Symptom Display does not light up when Power is pressedSymptom ??Bias annunciator displayed Symptom HiBias annunciator displayedDo not make Symptom Internal Reset Error displayedSymptom Configuration Error displayed Bit Description ActionMeasurements. Return Symptom Current Overrange DisplayedSymptom Dashes displayed instead of digits Symptom Bias voltage measurement changes by one digitExample 299.9 to Display Will Not Light Hours? Is the battery voltage greater than 5.9 volts? Low BatteryLine Bias ErrorGo to Model 35040 Therapy Dosimeter Fuse Replacement Line Fuse ReplacementReplaceable Parts Information Interface Connector CleaningCleaning The Instrument Replaceable Parts Information Warranty InformationReplaceable Parts List Recalibration, Repair Information & Technical AssistanceBlank Sample Documents Sample Customization Reports35040 Appendix Sample Customization Reports 35040 Appendix Sample Customization Reports Blank Timed Measurements Introduction New FeaturesOverview Specifications Update New Features B SetupMaking Timed Exposure Measurements Timer Setup ProcedureTimer Use Procedure Setup B RESET/MEASUREAutomatic Leakage Compensation ADC ALCOperation Instructions B Start NA pA Stop Thres CurrentDecimal Places Timer SetupTable B-1. Annunciators Annunciators, Indicators, and Overrange ConditionsTable B-2. Measurement Indicators and Conditions Condition Overranged Measurement1 Table B-3. Overrange ConditionsTheory of Operation Theory Of OperationConfiguration Error Service Required Error Number Measurement Displays Main MenuMeasurement Menu Figure B-9 shows the Measurement Displays dialog box Table B-4. Available Display Lines Figure B-10. The Timer Intervals dialog box Page Fluke Biomedical
Top Page Image Contents