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Validating, verifying, and calibrating flows

Validation, verification, and calibration all share the common goal of ensuring a process is working as intended. Here, we discuss these three interrelated but distinct processes and detail how to go about validating, verifying, or calibrating your system.

At a basic level, the three terms may be defined as follows:

• Validation ensures a system satisfies its stated functional intent
• Verification ensures a process or equipment operates according to its stated operating specifications
• Calibration ensures the measurement accuracy of an instrument meets a known standard

Validation: Is it producing the right results?

The outputs of a process are checked by the user to certify that the expected standard has been with upheld during the validation period. Usually an external organization will uphold the standard, but there may also be internal requirements to meet the standard. Commonly, users are compelled to validate that stack gas outputs comply with EPA requirements in power plants and refineries.

Verification: Is it working correctly?

Gauging parameters such as pressure or flow rate typically involves the insertion, temporarily, of a flow meter into a process. This task is part of the verification process, whereby the confirmation that a piece of equipment or a sup-process is working to the standard of the manufacturers technical design specifications as well as to confirm newly acquired instruments work correctly prior to installation. The undertaking of verification can also be completed during routine maintenance periods.

Performing validation and verification

The process is the same for both Validation and Verification, despite both having distinct goals. Simply, the procedure is as follows: Read a value and check to see if it falls within a specified range. Portable mass flow meters are particularly well-suited for quick and easy validation and verification.

• These battery powered devices last up to 18 hours, ensuring that multiple processes/instruments can be quickly checked.
• Multivariate measurement allows for validation or verification of process pressure, mass flow rate, or volumetric flow rate – all with one device.
• Low pressure drop configurations are available for processes with low system pressures and/or to minimize system impact.

In cases where the flow range of a single device isn’t quite enough, a portable calibration unit can be used. These units contain three high-accuracy battery-powered mass flow meters. Easy, swift verification of numerous process parts operating across a wide range of flow rates is what they are explicitly designed for.

Calibration: Is it still accurate?

In this two-step process, the user initially uses a calibration standard to confirm a flow value which then allows them to adjust the device undergoing testing to match the reading on the standard.

There are two types of standards:

• A primary standard is a universal measurement reference standard, such as those from the National Institute of Standards and Technology (NIST).
• A transfer standard is an instrument which has been directly calibrated using a primary standard.

Typically, Transfer standards are used instead of Primary standards due to the fact that Primary Standards are often highly expensive. For flow and pressure calibrations, Lab Unlimited’s high accuracy mass flow meters and pressure transducers can be used as transfer calibration standards.

Performing calibration

It is crucial that both accuracy requirements and operating range are taken into consideration when determining which instruments to use for Calibration. A single mass flow meter can be used to calibrate devices. These instruments measure with NIST-traceable accuracy to ±0.5% of reading or ±0.1% of full scale and have a flow measurement range of 0.01% to 100% of full scale (10,000:1).

• Higher accuracy calibrations may require an additional device, with a setup consisting of either two high-accuracy mass flow meters or one high-accuracy meter and one high-accuracy controller.
• Wider operating range calibrations may require a portable calibration unit, with a 100,000:1 operating range.
• Lab Unlimited also offers an FP-25 complete calibrator kit specifically designed for air quality monitoring applications.

Our applications engineers are always available to discuss your application and determine which solution is best for your process validation, verification, or calibration needs.