So get this... A customer sends us a dial pressure gauge, 0-3000 PSIG, rated at 1% of full scale by the manufacturer (±30 PSIG.) The customer wanted it calibrated to 0.5% of FS, which is ±15 PSIG. The gage is marked in 50 PSIG increments, with a needle that is maybe 1/4 as wide as the spacing between the markings and no parallax mirror behind the needle. Is the customer fooling themselves by wanting the gauge to be tighter than manufacturer's specs? Is it up to the calibrated eyeball of the technician to guesstimate what the resolution will be?
Even if we can adjust it to be dead on, there's no way we can guarantee it'll meet the customer's required specification after the calibration interval if the manufacturer's spec for that same interval is larger! If we say we calibrate something in accordance with the manufacturer's procedure but then we try to go tighter (as in the example above), then that means we're NOT following the manufacturer's procedure and can get whammied for it on an audit. So how would I word that on a calibration certificate, or do we just tell the customer if they want a tighter specification then go buy a more accurate gauge?
Even if we can adjust it to be dead on, there's no way we can guarantee it'll meet the customer's required specification after the calibration interval if the manufacturer's spec for that same interval is larger! If we say we calibrate something in accordance with the manufacturer's procedure but then we try to go tighter (as in the example above), then that means we're NOT following the manufacturer's procedure and can get whammied for it on an audit. So how would I word that on a calibration certificate, or do we just tell the customer if they want a tighter specification then go buy a more accurate gauge?



