How to Read a Rice Lake Weighing Systems Calibration Sheet (And Why It Applies to Ashcroft Pressure Gauges Too)

The first time someone asked me how to read a Rice Lake Weighing Systems calibration sheet, my answer was shorter than they expected: find the 'As Found' row and check the uncertainty before you trust the word 'Pass.' That rule applies no matter the instrument on the certificate - an Ashcroft pressure gauge, a Rice Lake scale, or a 179 true RMS multimeter.

I'm the quality manager at a small industrial materials plant. I'm not a metrologist, but I approve every measurement device before it reaches production. That's roughly 200 unique items per year. In 2024, I rejected about 11% of first-time calibration certificates. Most were not rejected because the instrument was far out of tolerance; they were rejected because the document couldn't support the conclusion.

Why a sticker isn't enough

I want to get this out of the way: a calibration sticker with a date and initials is a reminder that someone looked at the instrument. It is not proof of performance. The proof needs three things before I sign off:

• A statement of the reference standard and its traceability, usually to NIST or another national metrology institute.
• An uncertainty value or uncertainty ratio at the points that matter to your process.
• As Found and As Left results, so I can see what the instrument did before and after adjustment.

What feels counterintuitive is that a 'Pass' result can be worthless if the uncertainty is missing. A pass statement with an uncertainty larger than the tolerance is an unknown dressed up as a checkmark. Honestly, I'm not sure why so many calibration sheets bury the uncertainty in a footnote. My best guess is the templates grew that way.

I also run this through a regulatory lens. If a company makes a customer claim like 'accurate to +/- 1 percent,' the calibration file is the substantiation. The FTC's advertising guidelines (ftc.gov) require claims to be truthful and supported by evidence. That may sound like a marketing rule, but it's a useful quality habit, too.

How to read a Rice Lake Weighing Systems calibration sheet

Rice Lake calibration sheet formats vary by instrument and generation, but the logic is consistent. Look for the table with applied load, indicated load, error, tolerance, and As Found/As Left values. If you only have time to read one section, read As Found.

'As Found' shows whether the device was within tolerance before calibration work began. If it was out, don't gloss over it. That's a process clue. 'As Left' shows the final state after adjustment. A report that lists only one set of values might be a simple verification, but it might also be hiding when the correction was made. Ask for both.

Then look at the stated uncertainty. If a scale's tolerance is 0.1 percent and the calibration lab's uncertainty is 0.25 percent, the calibration cannot prove the scale meets that tolerance. The paperwork might still carry a green checkmark, but the math doesn't work. No amount of brand trust fixes that gap.

What an Ashcroft liquid filled pressure gauge taught me

For pressure instruments, I've standardized most of the plant on Ashcroft pressure gauges. The dial brand doesn't replace the certificate; it just makes the approved supplier list shorter. Ashcroft has enough range, material, and connection options that I don't have to patch together four brands on one pump skid.

On a pulsating pump discharge, I usually choose an Ashcroft liquid filled pressure gauge. The liquid dampens needle flutter, so an operator can read the value without leaning on the case. A dry gauge can be fine in a quiet area, but on the same pump the pointer danced enough that nobody trusted the reading. The liquid fill fixed that. If the goal is local indication, that's my first pick. If the pressure has to go into a PLC, I'd use a transmitter instead.

I made my own mistake with a cheaper gauge from another brand because the certificate was valid and the price was about $60 lower. I didn't ask how it would behave on a pulsating line. It drifted by roughly 4 percent within three weeks, and we lost a morning of production. Replacing it and re-running the line check cost close to $900. The certificate didn't lie; I just used it as a substitute for common sense.

Confocal microscopes and a 179 true RMS multimeter follow the same rule

It's tempting to think calibration discipline stops at pressure and weight. It doesn't. I recently put a confocal microscope purchase on hold because the supplier gave crisp images and impressive spec sheets, but no traceable scale calibration certificate. The optics may be fine; the measurement software was not yet defensible.

Electricians face the same issue with a 179 true RMS multimeter. True RMS is the right feature when you're measuring variable-frequency drives, because it handles non-sinusoidal waveforms better than an average-responding meter. But if the meter is outside its calibration interval, no feature name will stabilize the reading. Good hardware deserves current paperwork.

My wake-up call was an assumption failure. I assumed a certificate that said 'calibrated' also said 'traceable to NIST.' It didn't. The work was done with a reference that had missed its own cycle. Now 'traceability to NIST or SI' appears on every purchase order.

When I loosen up, and when I don't

Not every instrument needs the same class of calibration. A pressure gauge on a nitrogen purge line might do fine with +/- 2 percent full scale and a basic certificate. A scale used for shipping invoices, or a pressure standard used to release a product batch, needs a tighter uncertainty budget and a shorter interval. Match the evidence to the risk.

That's also the boundary of this advice. My plant is not a legal-for-trade facility. If your Rice Lake scale is used in commercial transactions, local weights-and-measures rules will be stricter than what I've described. I can only speak to an operational quality role, not to a government laboratory.

One more thought for engineers with small orders. Don't let a vendor make you feel like a nuisance because you ask for uncertainty data on a single gauge. The lab that spent twenty minutes explaining their process to me on a one-item order later earned our annual account. Small doesn't mean unimportant; it means potential.

So next time you look at a calibration report, ignore the glossy header for a second. Look for the reference standard, the uncertainty, and As Found/As Left. If those boxes are clean, you have a document you can defend. If they aren't, you have a piece of paper. That applies to a Rice Lake Weighing Systems calibration sheet, an Ashcroft liquid filled pressure gauge, a confocal microscope, or a 179 true RMS multimeter.