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Calibration Savvy
Calibration and Conformance
Calibration: Check a measurement against a known universally recognized standard to determine any deviation and correct for errors
Conformance: Check for agreement against internally defined values
THI Documents
Certificate of Conformance Certificate of Calibration Combined Test Report Calibration Data Sheets – ALL THI
metrology is NIST traceable NIST back up Documentation - $275.00
Certificate of ConformanceUsu
ally
free
!!
Certificate of Conformance
Question #1: Can a customer receive a certificate of conformance on a gauge tube?
Answer: Yes! We can verify that the tube’s output conforms to our acceptance criteria.
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Question #2: What other THI products could have a “C of C”?
Answer: Any of our products that have some output (signal or visual indication) that we can verify against our acceptance criteria.
NIST Traceable Metrology
Calibration Report
Question #3: Can a customer receive a calibration report for a gauge tube?
Answer: No. We can combine the gauge tube with the customer's meter and cable and perform a calibration against our NIST standards, but we cannot calibrate just a gauge tube.
Certificate of Calibration
ASK
NIST Back-up Documentation
Provides the customer with copies of all of our calibration documentation related to the metrology used for their instrument’s calibration.
In other words, THI has all of the calibration records for the metrology that we use.
NIST Back-up Documentation
Note: Most of the time… the customer doesn’t need all of this!
Definitions
Accuracy: closeness of a measurement of a quantity to its actual value
Repeatability: the degree of change in a repeated measurement under the same conditions
Useful Measurement: Accurate and Repeatable
Error Calculation
% Point =((IUT – STND)/ STND) * 100
Example for an HPM-760S:
Standard (STND) = 1.00 Torr
Instrument Under Test (IUT) = 1.01 Torr
% Point = ((1.01-1.00)/1.00)*100 = 1.0%
Full Scale Accuracy Calculation
Accuracy as a % Full Scale =((IUT – STND)/ FS) * 100
Example for an HFC-202: IUT = 100.04 sccmStandard = 100.02 sccmFull Scale of IUT (FS) = 100 sccm %FS = ((100.04-100.02)/100)*100 = 0.02%
Accuracy Statements
% FS (Full Scale) (HFC-202) % Reading (HPM-760) % Reading + % FS (HFC-D-302) % Reading + Constant (DVT, DAVC)
% of Reading (or % of Point)
Internal ID
Common Questions:
What is the accuracy of my gauge tube? Answer: Trick Question… need to know the
instrument being used to measure gauge tube output.
Digital Gauges have stated accuracy… but what is the accuracy of an Analog Vacuum Meter/Controller (e.g. VT-6A or CVT-26A)?
Answer: Depends on the region of interest.
Accuracy: Response Curve
Reference Tubes
What are they?- Evacuated/sealed glass gauge tube inside protective housing which simulate gauge tube output
How are they used? – Allow the customer to verify the heater current to the gauge tube and the readout of the meter movement or digital display. Gives verification of the electronics and cabling – BUT tells nothing about the gauge tube connected to system.
Certificate of Calibration – Reference tube
Other Flow Calibrations
Calibration Report Additional Points (10 points, 20 points, etc.) Multiple gas instances Polynomial Equation Manual
Ordering power supplies with flow instruments
Other Vacuum Calibrations
Specific Points on Data Sheet
Calibration in gases other than N2
(Must be inert)
(Requires Quality Plan)
Flow Calibration Reports
Common Sections Order Summary IUT Summary ( Instrument Under Test) IUT Condition Environmental Conditions Standard Conditions Reference Standard Documentation Test Data
Calibration Report: HFC-202
By Request
Published Accuracy & The GCF
GCF – Gas Correction Factor
Calibration Report: Test Data
Recorded Measurements Reference Flow Temperature Mass Flow
DUT (Device Under Test): Indicated flow Output VDC Flow in SLM
Estimated Uncertainty % FS and % PT
Calibration Report: HFC-D-302
Calibration Report: HFM-200 LFE
Combined Test Report
Working Pressure
Oxygen Clean
Calibration Report: HFM-201
Valve Check Test Report
All two stage valves ( 203/303/307) Automated Test
Other Industry Terms
Other Industry Terms
Turn Down Ratio: ratio of maximum flow to minimum flow at a stated accuracy
Rangeability: how much the range can be adjusted without major modifications
Zero Drift (offset error): how far from zero an instrument will change
Span Drift (span error): shift in the slope of the calibration curve
Other Industry Terms
Transducer Sensor Gauge Meter
-Vacuum: Electronics and display
-Flow: bypass, sensor, electronics
Other Industry Terms
Controller Flow meter with a solenoid valve or Set Point Relays
Power Supply – unit that converts AC “wall” current to DC “electronic circuit” current
Digital: microprocessor on board
Questions ??