Scope of Accreditation and CMC Drafting Guide

Purpose

The schedule (scope) of accreditation is the definitive statement of what the Laboratory is accredited to do. It is drafted by the Laboratory, assessed by the accreditation body, and published on the body's website. This guide explains how to draft it so that every entry is supported by evidence, is achievable in routine work, and is expressed in the format accreditation bodies expect. Verify the body's current format, terminology and CMC expression rules before submission.

What is inside

6 sections, about 2 pages when printed.

1. 1. Purpose
2. 2. Structure of a calibration schedule
3. 3. Deriving the CMC
4. 4. Worked examples
5. 5. Flexible scope
6. 6. Scope file

How to complete it

1. 1.Take the approved procedure budget (FRM-26) for the range.
2. 2.Replace item-specific contributions with those of the best existing device: a stable, high-resolution item of the type in question (for example a 4-wire PRT with 1 mK resolution; a digital pressure gauge with 0.001 % resolution). Do not use an ideal item that could not exist.
3. 3.Keep every Laboratory contribution: reference certificate, drift, readout, environment, gradients, method effects, and the repeatability of the process with the best existing device.
4. 4.Compute U (k = 2) at representative points; where the CMC varies across the range, fit a linear expression (a + b x) or split the range.
5. 5.Check the CMC against the reference standard's certificate uncertainty: the CMC cannot be smaller than the reference's uncertainty and is normally at least 1.5 to 2 times larger once drift, environment and repeatability are included.
6. 6.Check that routine job uncertainties are equal to or larger than the CMC; if routine work reports smaller uncertainties, the CMC or the budgets are wrong.
7. 7.Record the derivation (which budget, which best existing device assumptions) in the scope file so the assessor can follow it.

Before you use it

• Replace every square-bracket token, starting with [LABORATORY NAME], [ADDRESS] and [EFFECTIVE DATE]. The full token list is in GD-01 Read Me First.
• Have the content technically reviewed against how your laboratory actually works, then approved by the responsible manager before it becomes a controlled document.
• Update the Word fields after editing so the table of contents and page numbers are correct: select all, then press F9.
• Record the document in your own document register and set its review date.

Related documents

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• SOP-21

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• SOP-22

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  Calibration of hygrometers, RH probes and loggers against a reference hygrometer in a humidity generator or chamber.

• SOP-23

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  Calibration of gauges, transducers and indicators against pressure balances and reference transducers.

• SOP-24

  Electrical Calibration

  DC and low-frequency calibration of multimeters, calibrators and process instruments.

• SOP-25

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• SOP-26

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