An instrument calibration verification calculator confirms that instruments provide accurate and precise measurements by comparing their performance to a predefined standard.
Calibration Verification Calculator
The following is a thorough example of a pressure transmitter calibration with five points.
Calculator Inputs
- Instrument Reading: The value provided by the instrument being tested.
- Standard Value: The value from a reference standard or calibration standard.
- Tolerance: The acceptable range of error for the instrument.
- Full-Scale Range (FSR): The maximum range of the instrument.
Calculator Outputs
- Error: The difference between the instrument reading and the standard value.
- Percentage Full-Scale Error: The error expressed as a percentage of the full-scale range.
- Pass/Fail: Whether the instrument is within the acceptable tolerance.
Formula and Calculation Steps:
Step 1: Error Calculation
Step 2: Percentage Full-Scale Error Calculation
Step 3: Pass/Fail Determination
Check if the absolute value of the percentage full-scale error is within the specified tolerance.
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Example Calculation for a 5-Point Calibration of a Pressure Transmitter:
Let’s perform a calibration verification example for a pressure transmitter that operates within a negative to positive range. We’ll assume the following details:
- Full-Scale Range (FSR): -50 psi to 50 psi
- Standard Values (Reference Pressure): -50, -25, 0, 25, 50 psi
- Instrument Readings: -49, -24, 1, 24, 51 psi
- Tolerance: ±1% of full scale (1 psi)
Step-by-Step Calculation:
Full-Scale Range:
- Full-Scale Range (FSR): 100 psi (since -50 to 50 psi gives a range of 100 psi)
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Calibration Point 1:
- Standard Value: -50 psi
- Instrument Reading: -49 psi
- Error: −49−(−50)=1 psi
- Percentage Full-Scale Error: (1/100)×100=1%
- Pass/Fail: Pass (within tolerance)
Calibration Point 2:
- Standard Value: -25 psi
- Instrument Reading: -24 psi
- Error: −24−(−25)=1 psi
- Percentage Full-Scale Error: (1/100)×100=1%
- Pass/Fail: Pass (within tolerance)
Calibration Point 3:
- Standard Value: 0 psi
- Instrument Reading: 1 psi
- Error: 1−0=1 psi
- Percentage Full-Scale Error: (1/100)×100=1%
- Pass/Fail: Pass (within tolerance)
Calibration Point 4:
- Standard Value: 25 psi
- Instrument Reading: 24 psi
- Error: 24−25=−1
- Percentage Full-Scale Error: (−1/100)×100=−1%
- Pass/Fail: Pass (within tolerance)
Calibration Point 5:
- Standard Value: 50 psi
- Instrument Reading: 51 psi
- Error: 51−50=1 psi
- Percentage Full-Scale Error: (1/100)×100=1%
- Pass/Fail: Pass (within tolerance)
Table with Full-Scale Error Data
| Standard Value (psi) | Instrument Reading (psi) | Error (psi) | Percentage Full-Scale Error (%) | Pass/Fail (±1%) |
| -50 | -49 | 1 | 1 | Pass |
| -25 | -24 | 1 | 1 | Pass |
| 0 | 1 | 1 | 1 | Pass |
| 25 | 24 | -1 | -1 | Pass |
| 50 | 51 | 1 | 1 | Pass |
The calibration verification of the pressure transmitter is successful in this case because every data point falls within the designated full-scale error tolerance of ±1%.
By using this method the accuracy of the instrument is verified throughout its whole operating pressure range from negative to positive providing accurate readings for crucial applications.
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