Neometrix / Pressure Calibration Benches / Pressure Calibration Bench / NMX-PCL-42

NMX-PCL-42 · ENGINEERED-TO-ORDER CLASS — SET UP · PRELOAD · RISE · FALL · COMPARE · RECORD

Pressure Calibration Bench. A gauge is only as honest as what it was compared with.

Name: Pressure Calibration Bench
SKU: NMX-PCL-42

Every pressure reading on a rig, a plant or an aircraft traces back to a bench like this one. If the bench is wrong, every reading downstream is wrong by the same amount, and nobody can tell.

So the bench has two jobs. It makes a pressure that can be known without trusting another gauge, and it holds each instrument there long enough, rising and then falling, for the reading to mean something.

Discuss a pressure calibration bench Capability note (PDF)

A pressure calibration bench on a plain steel table: a piston and cylinder with a stack of mass discs, a hand-wheel screw press on a stainless oil reservoir, and a manifold carrying two plain cylindrical pressure transmitters, joined by thin stainless tubes, and no people

Fig · 01 — A pressure calibration bench: a mass stack on a piston and cylinder, a screw press, and a manifold carrying two plain transmitters — illustrative render.

The reference

mass on a pistonor a calibrated reference sensor

The medium

oil or gaschosen to suit the instrument

The method

preload, rise, fallsettled at every point

The record

as-found, as-leftone record per instrument

Status

engineered to orderno bench yet delivered

ISO 9001ISO 14001EURAMET cg-3 pressure balance referenceDKD-R 6-1 / EN 837 gauge referenceISO/IEC 17025 calibration reference

Overview

Why a pressure bench is proved by what it is compared against, not how it looks.

Because a calibration is only a comparison, and a comparison is only as good as the thing on the other side of it.

Fig · 02 — The bench in one picture: a pressure that can be known, held settled while rising and falling, and compared against the reading.

A calibration is a comparison. The reference makes it one.

What the bench is for

It gives a gauge, a transmitter or a switch a known pressure, reads what the instrument says, and records the difference. The reading is taken before any adjustment, and again after.

Why a dead-weight tester is the reference

A pressure balance is a piston floating in a cylinder under calibrated masses. The pressure it makes is the force divided by the effective area of the piston, so it rests on mass, area and gravity, not on another instrument.

Why local gravity matters

A mass weighs slightly different amounts in different places. The balance has to use the local value of gravity, and allow for the buoyancy of air on its masses, or the pressure it makes is quietly wrong.

Why height is a pressure

A column of oil is itself a pressure. The height between the piston and the instrument is therefore set or corrected, not ignored.

Why both directions are read

Gauges stick. The same gauge can read differently going up and coming down, so the bench reads rising and falling points, after a preload that frees the pointer.

Why the as-found reading is the valuable one

It shows what the instrument was doing in service. Adjusting it first throws that evidence away, so the bench records as-found before as-left.

The method

Set up, preload, rise, fall, compare, and record.

Six steps in a fixed order. The two shaded steps are the ones a quick check skips.

FIG · 02PRESSURE CALIBRATION BENCH · SET UP / PRELOAD / RISE / FALL / COMPARE / RECORD — THE INSTRUMENT IS JUDGED AGAINST THE REFERENCE

The step people underrate is the falling leg. A gauge that is right going up and wrong coming down has passed a check that only looked one way.

Fig · 03 — Three faults a bench must find: zero error, sticking and span error — a drawing of the idea, with no values.

1 · Set up

The instrument is mounted upright, the heights are set, and the lines are bled of air.

2 · Preload

Pressure is taken to full range and back, which frees the pointer and settles the instrument.

3 · Rise

Pressure steps up through the range, and each point is held until the reading has settled.

4 · Fall

The same points are visited again coming down, so any sticking shows.

5 · Compare

At every point the reading is set against the reference, and the difference is noted.

6 · Record

As-found and as-left readings are kept together, one record for each instrument.

Work content

What the bench contains, element by element.

Read it as a checklist: a bench missing a row will buy that row back later, usually as a certificate nobody quite trusts.

A close view of a single piston and cylinder unit: a polished piston rising from a plain cylinder housing into a round carrier plate, with a stack of six plain mass discs on a threaded stem above it and a braided tube leaving the housing, and no people

Fig · 04 — A piston and cylinder with a stack of mass discs on its carrier — illustrative render.

Element	What it does	What matters
Pressure balance	makes the reference pressure from mass on a piston	effective area established and traceable, local gravity known
Mass set	loads the piston in known steps	buoyancy of air allowed for, handled clean and dry
Pressure generator	raises and trims the pressure	a hand pump, screw press or intensifier chosen to the range and the medium
Manifold & valves	join the reference, the test ports and the vent	no trapped air, no dead volume, no leak
Test ports & adaptors	mount each instrument	upright, at a known height, with the right thread and a clean seal
Medium	carries the pressure	oil or gas to suit the instrument, with extra cleanliness for special services
Working temperature	keeps the reference stable	steady, and noted with every reading
Reference sensor	serves shop-floor work where a balance is too slow	itself calibrated against the balance
Data acquisition	logs rising and falling readings	as-found and as-left kept together, one record per instrument
Procedure	fixes the sequence	preload, rise, fall and settle, the same for every instrument
Testing & documentation	prove the bench, then every instrument	a worked uncertainty and a certificate the customer's laboratory can use

The element that decides whether a bench calibrates anything is not the pump. It is the reference. A bench with a doubtful reference only compares one doubtful reading with another.

Fig · 05 — One bench, three instrument families: gauges, transmitters and switches, all compared against the same reference.

Full specification — expand

Bench	A pressure reference, either a pressure balance with a calibrated mass set or a calibrated reference sensor; a pressure generator such as a hand pump, screw press or intensifier; a manifold with valves and a vent; test ports and adaptors that mount each instrument upright at a known height; a steady working temperature; data acquisition that logs rising and falling readings; a written procedure; and testing and documentation before handover
The One Idea	A gauge is only as honest as the last thing it was compared with. A dead-weight tester builds the pressure from mass, area and gravity, three things that can each be measured
Why A Dead-Weight Tester Is The Reference	A pressure balance is a piston floating in a cylinder under calibrated masses, and the pressure it makes is force divided by effective area, so it rests on mass, area and gravity rather than on another pressure instrument
Why Local Gravity Matters	A mass weighs slightly different amounts in different places, so a pressure balance must use the local value of gravity and allow for the buoyancy of air on its masses, or the pressure it makes is quietly wrong
Why Height Is A Pressure	A column of oil is itself a pressure, so the height between the piston and the instrument under calibration is set or corrected, not ignored
Why Both Directions Are Read	Gauges stick, so the same instrument can read differently at the same pressure going up and coming down; the bench reads rising and falling points after a preload that frees the pointer
Why As-Found Comes First	The as-found reading shows what an instrument was doing in service, and adjusting it first throws that evidence away, so the bench records as-found before as-left
Standards	EURAMET Calibration Guide No. 3 (cg-3) is the public reference for calibrating pressure balances, including effective area, local gravity and the buoyancy of air. DKD-R 6-1 and EN 837 are the public references for calibrating pressure gauges, including preloading, rising and falling points and hysteresis. ISO/IEC 17025 is the public reference for the competence of calibration laboratories. None of them sets the pressure ranges, the accuracy class or the medium for a particular site: that is set by the customer against their own instruments, and this page prints none of it. Accreditation of a laboratory rests with the customer and their assessors; none is claimed here
Configurations	A portable calibrator with a hand pump and a reference sensor, a dead-weight bench with a pressure balance, masses and a screw press, and a trolley system carrying several ranges on one cart
Scope Boundary	This is the bench that compares an instrument against a pressure reference. It is not a bench that applies pressure to a component for proof or burst (see hydraulic pressure test bench), not a portable pressure source (see TestPAC high-pressure testing unit), and not a torque calibrator (see motorized torque wrench calibrator)
Status	Neometrix has quoted against successive pressure calibrator and dead-weight tester requirements, and no delivered pressure calibration bench is claimed.

Configurations

One method, three ways to supply the bench.

The method, the record and the cleanliness rules are shared. What changes is the class of reference and how far it has to travel.

Portable calibrator

Shop floor and field

A hand-pumped comparator with a reference sensor, carried to the instrument rather than the instrument to the laboratory.

Dead-weight bench

The laboratory reference

A pressure balance with calibrated masses, a screw press and a manifold, for the highest class of comparison.

Trolley system

Several ranges on one cart

A wheeled system carrying more than one range and reference, so one cart serves a whole site.

Fig · 06 — Three ways to supply the bench, one method: a portable calibrator, a dead-weight bench, or a trolley system.

And the part that is not equipment at all, yet decides all three: the calibration procedure. It fixes the preload, the points, the settling and the rule for judging every instrument, so each one is read the same way.

Where it is used

Wherever a pressure reading has to be believed.

The common thread is a decision that rests on a number from an instrument nobody has checked lately.

Rig and plant instrumentation

Where the gauges and transmitters on test rigs and process plant are checked against a known pressure before they are trusted.

Aircraft and ground equipment

Where the gauges on servicing carts, test stands and aircraft systems are checked on a schedule.

Calibration laboratories

Where a reference is kept, and other instruments are compared with it.

After a knock or an odd reading

Where an instrument that has been dropped, or has read strangely, is checked before it goes back to work.

FAQ

Common questions.

Longer answers, for readers who want the reasoning.

Q · 01 Why is a dead-weight tester the reference rather than just another gauge?

Because it makes the pressure instead of measuring it. A piston floats in a cylinder under calibrated masses, and the pressure is the force divided by the piston's effective area. Mass, area and gravity can each be measured on their own and traced back to national standards, so the result does not depend on trusting any other pressure instrument. A second gauge, however good, is only ever a comparison with something else. EURAMET Calibration Guide No. 3 describes how pressure balances are themselves calibrated, including by cross-floating one balance against another.

Q · 02 What do local gravity and the buoyancy of air have to do with it?

The force a mass exerts depends on the local acceleration of gravity, which differs slightly from one place to another, so a balance has to use the value for where it actually stands. The masses are also lifted a little by the air around them, and that buoyancy is allowed for. EURAMET Calibration Guide No. 3 names both among the quantities the pressure calculation needs. A bench moved to another site therefore has its local gravity established again, not assumed.

Q · 03 Why is checking a gauge only on the way up not enough?

Because gauges stick. Friction and elasticity make many instruments read differently at the same pressure depending on whether it is rising or falling, and the gap is called hysteresis. Public calibration guidance for pressure gauges, DKD-R 6-1 and EN 837, therefore has the instrument taken to full range and back before the readings start, then read at rising and falling points, with the number of cycles depending on how accurate the instrument is meant to be. A one-way check can pass an instrument that a two-way check would fail.

Q · 04 Is this the same as the pressure test bench, the TestPAC or the torque calibrator pages?

No, and the differences are worth stating precisely. The hydraulic pressure test bench page is a hydrostatic and burst tester for tube assemblies, so it applies pressure to parts for proof and function. The TestPAC page is a compressed-air-powered unit that generates liquid pressure for testing, so it is a source of pressure, not a reference standard. The motorized torque wrench calibrator page calibrates torque wrenches, which is the same discipline applied to a different quantity. This page does not replace any of them, and it does not claim what they claim a second time.

Q · 05 What can a bench not do?

It measures an instrument's error; it does not remove it. An instrument that fails is adjusted or repaired separately, and the bench then proves the result. How good the comparison is depends on the class of the reference and on a steady, level, clean place to work, so a bench is only as good as the reference it carries. It also does not make a laboratory accredited: accreditation to ISO/IEC 17025 belongs to the customer's laboratory and its assessors, and this page claims none.

Q · 06 Has Neometrix built one of these?

We would rather answer this plainly than let a page imply otherwise. Neometrix has quoted against successive pressure calibrator and dead-weight tester requirements, and no delivered pressure calibration bench is claimed. What stands behind the offer is adjacent: Neometrix engineers pressure sources and hydraulic test equipment (see the TestPAC and hydraulic pressure test bench pages) and calibration equipment for another quantity (see the motorized torque wrench calibrator page). The pressure balance, the mass set and the reference sensors are specialist catalogue items, bought in and calibrated elsewhere, not invented. What Neometrix engineers is the bench around them: the pressure generation, the manifold and ports, the mounting, the data acquisition, the procedure and the records. So the honest position is that the bench is engineered to order, the neighbouring disciplines are in the building, and the first bench of this exact kind will be built around the customer's own instruments rather than lifted off a shelf.

Q · 07 Which standards apply, and who sets the ranges and the accuracy class?

EURAMET Calibration Guide No. 3 (cg-3) is the public reference for calibrating pressure balances. DKD-R 6-1 and EN 837 are the public references for calibrating pressure gauges. ISO/IEC 17025 is the public reference for the competence of calibration laboratories. None of them names the pressure ranges, the accuracy class or the medium a particular site must cover: that is set by the customer against their own instruments and the decisions that rest on them, and this page prints none of it. Acceptance of the finished bench, including its proving checks before handover, rests with the customer and whatever authority they name.

Q · 08 What do you need from us to quote?

Six things, and most of them describe your instruments rather than the bench. First, the instruments: gauges, transmitters or switches, and how many are checked in a day. Second, the ranges they cover. Third, the accuracy class you need, which sets the class of the reference. Fourth, the medium: oil, gas, or a service that needs an especially clean one. Fifth, the configuration: a portable calibrator, a dead-weight bench or a trolley system. Sixth, the site: the floor, the temperature, the power and who will run it. From that we come back with a layout drawing, a written method you can check, and a budgetary price.

The neighbouring pressure and calibration pages, and how they differ from this one.

Three neighbours: two that apply pressure, and one that calibrates a different quantity.

↗ Pressure on a part

Hydraulic Pressure Test Bench

Hydrostatic and burst testing of tube assemblies under supervisory control - it tests parts, it does not calibrate instruments.

↗ A pressure source

TestPAC High-Pressure Testing Unit

A compressed-air-powered unit that generates liquid pressure for testing - a source of pressure, not a reference standard.

↗ Another quantity

Motorized Torque Wrench Calibrator

Calibration of torque wrenches against a reference - the same discipline, for torque instead of pressure.

Browse all Neometrix product lines.

Get a quotation

Tell us the instruments, the ranges,
and the class you need.

The projects desk replies within two working days with a layout drawing, a written method you can check, and a budgetary quotation. Write to [email protected] or use the form.

Enquire — pressure calibration bench Capability sheet (PDF) +91 7777 876 876

ISO 9001 / 14001 ENGINEERED-TO-ORDER CLASS — PRESSURE CALIBRATION BENCH SET UP · PRELOAD · RISE · FALL · COMPARE · RECORD — THE INSTRUMENT IS JUDGED AGAINST THE REFERENCE ENGINEERED IN NOIDA · INDIA