Take Me to Your Meter!


(Photos above: (L-R) Rosemount Pressure Transmitter, Emerson Radar Level Transmitter &  Fluke Process Calibrator | courtesy of Powers of Automation, Inc.)

Automated manufacturing and production equipment requires calibration of its instrumentation to ensure products are manufactured to specification. A company benefits from calibration by delivering a consistent product, increased product quality, and reduced waste or rework. A company may be required to have instrumentation calibrated to comply with regulatory requirements like the Code of Federal Regulations for manufacture of pharmaceuticals, biologics, or medical devices, or required by ISO (International Organization for Standardization) standards for quality and environmental stewardship.

Automated processes utilize instrumentation, known as transmitters, to measure temperature, pressure, flow, level, conductivity, weight, volume, etc. Brewing beer is a typical automated process. When a new batch is started, the automated system fills a tank with the required amount of grains. The instrumentation measures the weight of the tank, and the grain conveyor is stopped it when the desired weight of grain is correct. The tank is filled with water using instrumentation to measures the level or flow into the tank. The temperature is increased and monitored by a temperature transmitter. The new beer (wort) is transferred to the fermentation tank where the temperature is controlled, again by utilizing a temperature transmitter. The brewery benefits from having the temperature transmitters, weigh scales, level transmitters, and flow meters calibrated because the system repeatedly produces a consistent quality of beer and the company can control their raw material costs.

Calibration is defined as “is the comparison of measurement values delivered by a device under test with those of a calibration standard of known accuracy”. (from Wikipedia) In other words, the calibration of a temperature transmitter requires that its readings are compared to another temperature standard that is proven to be accurate (reference standard). The reference standards are sent to a calibration laboratory annually to verify their accuracy. Reference standards may also be an intrinsic standard, like ice water. A properly prepared ice water bath will be 32.0 °F , +/- 0.1 °F. Salts are used as relative humidity intrinsic standards. The National Institute of Standards and Technology (NIST) has intrinsic standards for many measurements, including the standard for time that is based on a cesium atomic oscillator.

Powers of Automation worked on a project to update an instrument used to measure biological oxygen demand (BOD). The BOD is measured to prevent excessive airplane deicer entering the surrounding waterways at airports. The natural bacteria will use all the oxygen in the water as they consume the deicer, resulting in the fish and aquatic animals dying. The instrument was old, and parts were impossible to find. This instrument required calibration every day because it measured BOD by feeding the measurement sample to a colony of bacteria. POA provided a creative solution to allow daily calibration that measured the health of the colonies and adjusted the BOD reading accordingly. This was a fun project and a challenging opportunity for our team.

Powers of Automation provides calibration services across the country with the majority of our clients located in Oregon and California. Our capabilities include pressure, temperature, relative humidity, flow, level, weight, conductivity, pH, amperage, voltage, resistance, and RPM. POA provides complete calibration programs and will notify you in advance when your instrument calibrations are coming due. The accuracy of our reference standards are traceable to NIST. Our quality system is certified to ISO9001:2008 (currently transitioning to the 2015 standard). POA has been providing calibration services for 15 years with continual and steady business growth averaging 10 to 30% year over year.


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Steve Powers

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