Figure 2: A common 34 Liter NIST traceable Dry Gas Cylinder and Regulator.
adjust calibration standards based on the actual atmospheric pressure at the eleva- tion of calibration.
The QAP A Quality Assurance Plan (QAP)
regulates equipment operation and training when used in evidential workplace testing. A QAP is issued by each manufacturer for their model of device and is approved by National Highway Traffic Safety Administra- tion (NHTSA) before the device is added to the Conforming Products List (CPL) as an Evidential Breath Testing device. Both the instrument manufacturer and the user have responsibilities outlined in the QAP.
Manufacturers QAP Responsibilities
Effects of Altitude on Dry Gas Standards
Changes in atmospheric pressure explain
why water boils at 212°F at sea level but only 202°F in Denver. Atmospheric pressure change also
explains why Dry Gas standards must be adjusted for altitude. Neither the stove nor the Breathalyzer behave differently in Denver than at sea level. However, since the Dry Gas standard used for calibration is manufactured to give the correct ethanol va- por concentration and pressure at sea level, correction factors are required when the instrument is calibrated at higher altitudes. Users will be familiar with Altitude Cor-
rection Charts found on Dry Gas cylinder labels that correct gas standards for the effects of altitude. Tese charts provide cor- rection factors in 500 foot increments. An easier and more accurate method is to use EBTs equipped with on-board barometric pressure sensors, which automatically
20 datia focus
1. Te manufacturer must specify the methods used to perform external calibration checks on the EBT, the tolerances within which the EBT is regarded as being in proper calibration, and the intervals at which these checks must be performed. In designating these intervals, the QAP must take into account factors like frequency of use, environmental conditions (e.g., temperature, humidity, altitude) and type of operation (e.g., stationary or mobile).
2. Te QAP must also specify the inspec- tion, maintenance, and calibration requirements and intervals for the EBT.
3. Te manufacturer must include, with each EBT, instructions for its use and care consistent with the QAP.
User/Service Agent/Employer QAP Responsibilities
1. Users must follow the manufacturer’s instructions including performance of external calibration checks at the inter- vals the instructions specify. If the Cal Check result is within the acceptable tolerance defined in the QAP for that device, the EBT is considered accurate. If the result is outside of the acceptable
tolerance, the EBT is not providing ac- curate readings and must be calibrated.
2. In conducting external calibration checks, users must use only calibration devices appearing on NHTSA’s CPL for “Cali- brating Units for Breath Alcohol Tests.”
3. If an EBT fails an external check of cali- bration, users must take the EBT out of service immediately and may not use the EBT again for DOT alcohol testing until it passes an external calibration check.
4. Users must maintain records of the inspection, maintenance, and calibra- tion of EBTs.
5. Users must ensure that the inspection, maintenance, and calibration of the EBT is performed by its manufacturer or a maintenance representative certi- fied either by the manufacturer or by a state health agency or other appropriate state agency.
Record keeping is an important user
responsibility. Under DOT regulations, inspection, maintenance and calibration re- cords of EBTs must be kept for a minimum of two years. Federal Motor Carrier Safety Administration (FMCSA) requires 5-year record retention. Calibration Log Books are available for record keeping. Informa- tion may be handwriten but best practice is to retain and sign the actual calibration and calibration check printouts.
How Often Do I Calibrate My Instruments?
Calibration and cal checks are required
for all EBTs. Te DOT Regulations for calibration checks and calibrations are very clear. Every EBT has a manufacturer supplied, and DOT approved, Quality As- surance Program (QAP) which spells out the device specific requirements for both the manufacturer and the users. QAPs are not identical across all makes and models of instruments because the steps required (and with some units, the tools required) to properly calibrate devices differ by manufacturer. Differences between makes
spring 2013
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