The commissioning records for the one you are replacing will be on record.
Find them. The data collected at the inaugural commissioning will indicate what tests are to be performed and what needs to be recorded. The test procedure may even be there.
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Difficulty is not an obstacle it is merely an attribute.
Obtain the bellows manufacturer's technical information sheets for the equipment and follow the test instructions therein.
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"Did you get my e-mail?" - "The biggest problem in communication is the illusion that it has taken place" - George Bernard Shaw, 1856