Are you considering on calibrating pressure instruments in house?  Then there are a few things to think about before setting up the lab and committing to a scope of calibration.  Once you have the answers to your questions, you must choose a pressure standard to use in the calibration.  The standard can be any pressure sensing device, that has a range and accuracy capable of covering all the devices being tested, from controllers, transducers, digital gauges to deadweight testers and portable devices.

  • Review or create an in-house quality procedure
  • Determine the level of calibration required
    • Do you need traceability to NIST or other national institutes?
    • Is a calibration accredited to ISO 17025 necessary?
    • Can you verify without traceability or accreditation?
    • Are there requirements for an as-found calibration and/or an adjusted as-left calibration?
    • Do you have personnel trained in these procedures?

Accuracy specifications are sometimes reported as a percent of full-scale range or as a percent of reading down to a specific percent of full scale.  In either case the accuracy of the standard and the accuracy of every DUT you plan to calibrate must be compared to make sure the standard has enough accuracy in every case. 

Many pressure calibrators are equipped with multiple internal transducer ranges and multiple pressure controlling channels for exactly this reason.  This information will guide you in determining if you already have an appropriate pressure standard or if you will need to purchase more.

The calibration will consist of generating a range of pressure points determined by your procedure. These points must be stable enough to record a simultaneous reading from the standard and the DUT. The pressure difference between the standard and the DUT is recorded as the error.

Generation of a common pressure to the standard and to the DUT can be accomplished using various devices such as:

  • Deadweight tester
  • Manual pressure pump and volume controller connected to the DUT and a transducer or indicator
  • An automated pressure controller.

In any case, the pressure difference between the standard and the DUT for each calibration point is recorded as the error. These data points can be compiled into a record that can serve as the calibration report. The initial calibration or "as-found" calibration shows the initial state of the DUT. If the DUT is found to have errors exceeding its accuracy specification, corrections can be made to bring it into compliance (reference the manufacturer's manual for instructions). After corrections have been made, an as-left calibration can also be done to verify the corrected values.

For more information on how to calibrate pressure instruments, check out this video : How to calibrate Pressure Instruments

Our scientific equipment calibration in Ohio clientele ranges from private laboratories, hospitals to universities. Contact Scientific Instrument Center and learn more about our laboratory and medical equipment calibration. To inquire about our services, you may contact us or give us a call at (614) 771-4700. 
We are here to answer any questions you may have.