A working quality system can be the difference between winning a large order of cables and losing to a company with a quality system in place. For example, a quality system helps you keep track of calibration dates and practices. The following information explains how to use your quality system to keep your instruments calibrated.
These standards are quality system requirements for organizations that perform quality tests and use calibrated equipment. Establishing a quality system per the standards ensures that tests are done competently and lends credibility to the organization. In the United States, common quality standards include ANSI/NCSL Z540-1, ISO/IEC Guide 25, ISO 10012-1, ISO/IEC 17025, and the former MIL-STD 45662A.
You can review the ANSI/NCSL Z540 standard referred to above, as well as other helpful metrology information from the National Conference of Standards Laboratories International (NCSL) at 1-303-440-3339 or www.ncsli.org. You can also review the ISO standards from the International Standards Organization (ISO) at their website www.iso.net.
In metrology industry, the word “standards” often refers to a centralized, most accurate unit of measurement regulated by countries. The National Institute of Standards and Technology (NIST) maintains the national standards for measurements in the United States.
Quality Practices for Calibration
Part of your quality system is making sure your instruments are calibrated. Quality Standards, such as ANSI/NCSL Z540-1 and ISO 10012-1, require several good practices for the calibration industry including the following areas:
Have a recall system in place to ensure instruments are calibrated in a timely manner. Use a system the includes calibration dates, due dates, calibration sources, and other instrument records.
When you have verified an instrument’s calibration, the quality standards require you to label the instrument as such. These labels, applied to instruments, have fields for the instrument serial number, verification date, verification due date, and by whom it was verified.
Wherever possible, quality standards require an accuracy ratio of at least four to one. In other words, the instrument being used to measure the calibrated instrument should be at least four times as accurate as the calibrated instrument.
Performance Verification Certificate
The Performance Verification Certificate is a record of who, when, and by what equipment the instrument was verified.
Verification Data Report
Some organizations require a written report of the measured values of a calibrated instrument when that instrument is calibrated. Calibration laboratories typically charge extra to create a data report. However, when an instrument is found to be out of tolerance, the quality standards require a record of the out-of-tolerance data in relation to the instrument specifications. A verification data report can fill this requirement. Photocopy the Verification Data Sheet and fill it out.
Traceability refers to each valid verification going back to national standards such as those maintained by the NIST in the United States. To maintain traceability, qualified personnel must perform the performance verification under controlled conditions, using correctly calibrated instruments, with correct test accuracy ratio.
Several years ago, NIST numbers (i.e. reference numbers issued on NIST reports) were commonly copied on successive calibration certificates as a means of showing traceability. This practice has been discontinued. Therefore, if you are writing a performance verification procedure, do not require NIST numbers be copied on reports to show traceability. NIST numbers are sometimes confused with other numbers that calibration laboratories create for reference such as “asset numbers,” “NIST trace numbers,” “ID numbers,” and report numbers. For more information regarding the discontinued use of NIST numbers, Cirris can provide a copy of the position paper from the National Conference of Standards Laboratories.
For More Information
The following links can help with a quality system both for calibration and overall.
Keep your Cirris tester calibrated by ordering a Performance Check Kit.