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 ??