Solving Humidity Calibration Challenges In Today’s Metrology Lab0 pages

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Solving Humidity Calibration Challenges In Today’s Metrology Lab
Author/Speaker: Jeff Bennewitz
Thunder Scientific Corporation
623 Wyoming Blvd. SE
Albuquerque, NM 87123 U.S.A.
Email: jeff@thunderscientific.com
Phone: (505) 265-8701; FAX: (505) 266-6203
Introduction/Abstract
Two-pressure humidity calibration technology has long been the recognized standard for on site instrumentation calibration, test and verification. The goal of this paper is to provide a tool to help you as a metrologist take advantage of the benefits of this technology so you will be able to apply the information to your daily laboratory applications. This paper will cover the operation and benefits of modern two-pressure humidity calibration systems, explain how you calibrate them, provide some sample applications and a brief history of the technology.
The Importance of Reliable Humidity Calibration in Your Lab
Whatever your industry, your end product is only as good as the calibration it has received. Therefore, the equipment used to calibrate or test the limits of your end product must be first, a reliable, proven technology and, second, be presented in equipment that is easy to use and also easy to validate for optimum operation parameters; preferably at your laboratory, in-house.
Whether you are calibrating transducers, tools for silicon wafer production, controlling comfort levels in HVAC systems or are involved with the tight humidity management required in manufacturing moisture sensitive products such as film, semiconductors, and pharmaceuticals, you are stepping up your demand for increased reliability and accuracy in humidity measurements. Today, calibration systems are required to both obtain and maintain a 4:1 accuracy ratio. To accomplish this, humidity and dew point hygrometers must be calibrated against a source of humidity at a stable test temperature.
The most accurate and reliable method of continuous humidity generation in use today for the range of ~5-98% RH is based on the “two-pressure” principle originally developed by the National Institute of Standards and Technology (NIST). The two-pressure principle is used in the most accurate on-site calibration and verification systems. These are mobile and self-contained, with an integral humidity generator that is capable of simulating a wide range of temperature/humidity values with sufficient accuracy and consistency to maintain strict 4:1 calibration ratios. In a 10-year track record, this has been the only system of its kind that can meet tight tolerance requirements. It is still the primary standard of choice for humidity calibration.