I am working at a power plant under a ISO certified company. We have standard calibration procedure and calibration record sheet. During last ISO audit, Bureau Veritus auditor wanted to know why there is no tolerance limit or acceptable error not mentioned in our sheet. Our plant is a big Combined Cycle Power Plant and there are a lot of instruments from different manufacturers for various purpose. We have equipment for calibration which also calibrated every year from ISO accredited laboratory.

I want to know how can I set standard acceptable error for these instruments. If there are guideline or practical data which can be followed please let me know.

 

During last ISO audit, Bureau Veritus auditor wanted to know why there is no tolerance limit or acceptable error not mentioned in our sheet
... Is that Veritas or Veritus.. Never heard about Veritus...

 

Pages 2-4 (pdf) of publicly available first chapter of the ISA publication, Calibration Principles, gives a broad overview of instrumentation calibration tolerances.

https://www.isa.org/getmedia/a9356c...f8dd3e7ba/calabration-principles-chapter1.pdf