FAQ: Recalibration of Alicat Devices

When do I need to get my Alicat device calibrated?

We recommend sending your units back for yearly calibration. This upholds your lifetime warranty and allows our service department to check for any damage to the device. Over time minor physical changes to the laminar flow elements and pressure sensors inside the device and particulate deposits can cause the instrument’s calibrated flow curve to inaccurately represent the actual characteristics of the flow path. With an annual recalibration, instruments are brought back to their optimal calibration specifications and, if need be, can be cleaned.

What is included in an annual recalibration?

Every recalibration starts with an evaluation.  Our service technicians will double check analog signals, settings, sensor health, LCD functionality, threads and even cosmetic issues like a scratch on the display.

After careful evaluation, our service technician will log “as found” data showing how precisely calibrated the unit was when it arrived. The device is then compared to our local barometric pressure and a NIST traceable standard and calibration adjustments are made to achieve the closest to ideal calibration possible. If anything is noticed to be out of sync, we work with the customers to make sure they understand the condition of their Alicat and how we will recalibrate and, if needed, repair the device.

Additional benefits of annual recalibration

When a device is sent in for recalibration it is an opportunity not only to maintain the quality and precision of the device, but also an opportunity to update firmware or, if your application needs have changed, the perfect time to work with our Application Engineers to find a solution that allows your Alicat to be adjusted or even customized to meet your evolving needs without the hassle and expense of buying a whole new instrument. Many reconfiguration options are available for Alicat devices—from updating the display to changing the flow range.

On the calibration certificate

Annual calibration includes a NIST traceable calibration certificate with before and after recalibration data. On the calibration certificate, we list certain parameters and conditions related to the calibration:

  • P/D/I values: These are the default tuning settings on the device. Note: most units will only have P and D settings.
  • Process gas: The pre-selected gas from the gas menu. This can be changed through the front panel or during recalibration.
  • Calibration gas: The gas used to calibrate the unit. Unless a customer specifically asks for an actual gas calibration, we typically use air.
  • Range: The full scale range of the unit. Since we can configure devices with custom ranges, this may not match the body size found in the part number.
  • Gas temperature: The temperature of the gas that was used to calibrate the device at our facility.
  • Ambient humidity: The humidity of our facility at the time of calibration.
  • Calibration procedure/rev #: The standard procedure and revision used to calibrate the gas.

Below this there is a list of standard tools used to calibrate the unit. Every standard tool used to calibrate the units has an associated calibration chain, to keep all units NIST traceable. This list shows our standard tool’s name, that tool’s calibration due date, manufacturer and model number and uncertainty. Some units listed in this section are Alicat units. These are primary transfer standards, with high accuracy calibration. They are used for calibrating devices to our standard (as opposed to “high”) accuracy procedures.

For recalibrations, you will also get as found and as left data. This lets you know if the unit was in spec when it arrived at the calibration facility, and if not, which points were out of tolerance. This also shows the uncertainty, calibration pressure and units of measure. In the “as found” and “as left” sections, the “D.U.T.” is your Alicat device being calibrated and “Actual” is the reading from the high accuracy device it is being compared to. The outputs are the analog inputs and outputs.

How do I get a recalibration from Alicat?

To order a calibration through Alicat, use the service request form. On receipt of your request, we’ll issue you an RMA (Return of Materials Authorization) and send you shipping instructions. If you’re close to one of our regional calibration or service centers, you should contact that center for an RMA.

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