C-04

Pressure calibration

Gauges, transmitters, switches and vacuum instruments calibrated across their working range, with the as-found reading recorded before any adjustment.

What it is: Gauges, transmitters, switches, vacuum instruments
Who it is for: Autoclaves, retorts, steam systems and control loops
Turnaround: 3–10 working days

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WHAT THIS IS

What this is, and why it matters

Pressure calibration compares an instrument against a reference across its range, typically at both rising and falling points so that hysteresis becomes visible. It covers analogue and digital gauges, pressure transmitters feeding a control system, pressure switches that trip at a set point, and vacuum instruments. Switches are calibrated on the value that actually matters for them — the pressure at which they genuinely change state, which is not reliably the value printed on the dial.

The as-found data is the whole point. An instrument that is adjusted before it is measured erases the only evidence of whether it was correct during the period it was in service — and that period is precisely the one your existing records already relied on. Where the instrument sits on a steriliser, an autoclave, a pasteuriser or a pressure vessel, its reading is also a safety statement, and the certificate is what supports it if anyone comes asking.

What this lane covers

Analogue and digital pressure gauges
Transmitters, switches, vacuum gauges

TRIGGERS

When you need it

The instrument is on safety-critical equipment

Autoclaves, retorts, steam systems and pressure vessels are governed by their pressure readings. Calibration is a quality requirement and part of the safety case at the same time.

A transmitter feeds a control loop

A control system is only as accurate as the instrument feeding it. A drifting transmitter moves the whole process with it and never triggers an alarm, because as far as the system is concerned nothing is wrong.

A process validation depends on it

Validating a thermal process, a filtration step or a filling operation produces evidence that is worth exactly as much as the instrumentation that recorded it.

PROCESS

How it works

Identify the instrument and the range you use
Instrument type, range, units, and whether it is a gauge, a transmitter or a switch — they are calibrated differently. For switches, the set point it is supposed to trip at; for transmitters, the output signal the control system reads.
Coverage confirmed against the accredited scope
The laboratory confirms whether your instrument and range sit inside the accredited scope before quoting. Where they do not, that is said plainly rather than quietly absorbed — the scope annex is published on this site precisely so the boundary is checkable.
Measured as found, before any adjustment
The as-found reading is recorded first, always. It is the only evidence of whether the measurements you have already taken and acted on were sound, and adjusting the instrument before measuring it destroys that evidence permanently.
Certificate issued against traceable references
The certificate states as-found and, where an adjustment was made, as-left readings at each point, rising and falling, each with uncertainty, plus the reference used and its traceability.

What you get back

A certificate carrying as-found readings at each point across the range, as-left readings where anything was adjusted, the uncertainty at each, and the reference standard behind them.

Scope facts

Parameter	Value	Note
Accreditation basis	ISO/IEC 17025:2017, accredited by the Saudi Accreditation Center.	Publishes from the certificate document.
Accredited ranges and CMC	Calibration: mass, mechanical, temperature and chemical measurements, published line by line with range and CMC. Testing: food and agricultural microbiology, covering aerobic plate count, Escherichia coli, coliforms and Enterobacteriaceae.	Publishes from the scope annex. No range is estimated.
Collection and on-site service	Non-portable instruments are calibrated at your premises. Portable items may be submitted to the laboratory, or collected by our personnel for an additional pickup fee. Standard turnaround is 3 to 10 working days from acceptance.	Confirmed service routes only.

Q+A

Common questions

Pressure

Can the gauge be calibrated while it is on the line?

No — calibration compares the gauge to a traceable reference under controlled, applied pressure, which cannot be done while it sits live on the process. The laboratory confirms arrangements in writing so removal is planned, not improvised.

Why are readings taken rising and falling?

Because pressure instruments can read differently on the way up than on the way down — hysteresis — and a single direction hides it. Points across the range, taken in both directions with uncertainty stated per point, describe how the gauge actually behaves.

The gauge does not sit exactly on zero — has it failed?

Not by itself. The judgement is made against the tolerance your measurement needs, using the as-found data across the range — not against the zero mark alone. The basis for any pass or fail statement is agreed in writing before the work.

Which certificate figure do I file — as-found or as-left?

Both, and they do different jobs. As-found judges every measurement made since the last calibration; as-left is the starting point for the next interval. A certificate that only shows as-left has quietly deleted the number you most needed.

How often should pressure gauges be calibrated?

That is your decision, made from as-found history and how critical the measurement is — the laboratory does not impose an interval. A gauge protecting a critical measurement earns a shorter interval than one on a utility line, and the as-found record is the evidence for either.

Send the sample question or the instrument list. It is read by a bench professional, not routed through a ticket queue. Confirmed phone, mailbox and address publish here at launch.

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