Neometrix / Flow Calibration Rigs / Flow Calibration Rig / NMX-FCR-43

NMX-FCR-43 · ENGINEERED-TO-ORDER CLASS — SET UP · SETTLE · DIVERT · COLLECT · COMPARE · RECORD

Flow Calibration Rig. The reference for flow is a scale and a clock.

Name: Flow Calibration Rig
Brand: Neometrix
SKU: NMX-FCR-43

A flow meter reports a number, and nothing inside the meter can say whether the number is right. Someone has to run a known quantity of liquid through it and compare.

So the rig has two jobs. It collects and weighs the fluid over a timed interval, so the reference is mass and time, and it holds the flow steady long enough for the meter's reading to mean something.

Discuss a flow calibration rig Capability note (PDF)

A flow calibration rig on a laboratory floor: a pump skid on the left, a straight pipe run with two plain cylindrical flow meters and a diverter box in the middle, and a square stainless weighing tank on a load-cell platform on the right, joined by stainless pipes, and no people

Fig · 01 — A flow calibration rig: a pump skid, two meters in a straight run, a diverter, and a weighing tank on a load-cell platform — illustrative render.

The reference

a scale and a clockor a proved master meter

The liquid

water, oil or fuelchosen to suit the meter

The method

settle, divert, weighsteady flow, then compare

The record

error at each flow rateone record per meter

Status

engineered to orderno rig yet delivered

ISO 9001ISO 14001ISO 4185 weighing method referenceISO/IEC 17025 calibration reference

Overview

Why a flow rig is proved by what it weighs, not what it pumps.

Because a pump can move any amount of fluid. Only a scale and a clock can say how much, and how fast.

Fig · 02 — The rig in one picture: a steady flow, diverted into a weighing tank on a signal, and the meter compared with mass and time.

The meter is compared with mass and time, not another meter.

What the rig is for

It runs a known quantity of liquid through a flow meter or flow sensor and records how far the reading is from the truth at each flow rate. The reading is taken before any adjustment, and again after.

Why a scale and a clock are the reference

In the weighing method, flow is the mass of liquid collected divided by the time it took. Mass and time can each be measured and traced back to national standards, so the meter is compared with neither a guess nor another meter.

Why the diverter matters

The flow is never stopped. A diverter swings the stream from a return line into the weighing tank and back again, and the time it takes to move is itself an error that has to be measured and kept small.

Why air and temperature matter

Air lifts the weighed liquid a little, as it lifts any mass, so the weight is corrected for buoyancy. The density of the liquid is also needed, at the temperature it actually had.

Why steady flow comes first

A meter read while the flow is still settling reads wrong. The rig holds each flow steady, with pressure and temperature settled, before the collection starts.

Why a master meter has a place

A weighing run is slow. A master meter, itself proved against the weighing rig, sits in line beside the meter under test and shares the flow, so many meters can be checked quickly against a traceable reference.

The method

Set up, settle, divert, collect, compare, and record.

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

FIG · 02FLOW CALIBRATION RIG · SET UP / SETTLE / DIVERT / COLLECT / COMPARE / RECORD — THE METER IS JUDGED AGAINST MASS AND TIME

The step people underrate is the settling. A meter read while the flow is still finding its level has been compared with a flow nobody was weighing.

Fig · 03 — Three faults a rig must find: zero offset, slope error and scatter — a drawing of the idea, with no values.

1 · Set up

The meter is fitted in line, with the pipe run it needs, and the line is filled and bled of air.

2 · Settle

The flow is set and held steady, with pressure and temperature settled, before anything is collected.

3 · Divert

On a signal, the stream is swung into the weighing tank, and the clock starts with it.

4 · Collect

The liquid is weighed and timed over the whole interval, and the diverter then swings the stream back.

5 · Compare

The meter's reading is set against the collected mass divided by the time.

6 · Record

The error at each flow rate is kept, as-found and as-left, one record for each meter.

Work content

What the rig contains, element by element.

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

A single two-way diverter valve in an enclosed bolted stainless housing with a small cylinder actuator on its side, one outlet pointing down into the open top of a square stainless weighing tank and a second outlet turning away into a return pipe, and no people

Fig · 04 — A two-way diverter over a weighing tank, with an actuator that swings the gate on a signal — illustrative render.

Element	What it does	What matters
Flow source	sets and holds a steady flow	a pump and control valve chosen to the range, with pulsation damped
Weighing tank & scale	weigh the collected liquid	load cells traceable, buoyancy of air allowed for
Diverter	swings the stream into and out of the tank	quick and repeatable, with its own delay measured
Timer	measures the collection interval	triggered by the diverter itself, not by an operator
Master meter	serves routine work	itself proved against the weighing rig
Test lines	hold the meters under test	straight pipe runs, bled of air, fitted to the maker's rules
Temperature & density	convert between mass and volume	measured where the liquid is used and noted with every run
Reservoir & conditioning	keeps the liquid clean and steady	filtered, degassed and held at temperature
Data acquisition	logs flow, mass, time and temperature	one clock for every channel, one record per meter
Procedure	fixes the sequence	settle, divert, collect and compare, the same for every meter
Testing & documentation	prove the rig, then every meter	a worked uncertainty and a certificate the customer's laboratory can use

The element that decides whether a rig calibrates anything is not the pump. It is the reference. A rig that cannot weigh or time what it collects only compares one meter's opinion with another's.

Fig · 05 — One rig, three meter families: volumetric, electronic and mass meters, all compared against the same weighing reference.

Full specification — expand

Rig	A flow source with a pump and control valve that sets and holds a steady flow; a weighing tank on a scale with load cells; a diverter that swings the stream into and out of the tank; a timer triggered by the diverter itself; a master meter for routine work; test lines that hold the meters under test; temperature and density measurement; a clean, conditioned reservoir; data acquisition on one clock; a written procedure; and testing and documentation before handover
The One Idea	The reference for flow is a scale and a clock. A gravimetric rig collects the fluid, weighs it and times it, so the meter is compared with mass and time, not with another meter
Why A Scale And A Clock Are The Reference	In the weighing method, flow is the mass of liquid collected divided by the time it took, and mass and time can each be measured and traced back to national standards, so the meter is compared with neither a guess nor another meter
Why The Diverter Matters	The flow is never stopped: a diverter swings the stream from a return line into the weighing tank and back, and the time the diverter takes to move is itself an error that has to be measured and kept small
Why Air And Temperature Matter	Air lifts the weighed liquid a little, as it lifts any mass, so the weight is corrected for buoyancy, and the density of the liquid is needed at the temperature it actually had
Why Steady Flow Comes First	A meter read while the flow is still settling reads wrong, so the rig holds each flow steady, with pressure and temperature settled, before the collection starts
Why A Master Meter Has A Place	A weighing run is slow, so a master meter that has itself been proved against the weighing rig sits in line beside the meter under test and shares the flow, letting many meters be checked quickly against a traceable reference
Standards	ISO 4185 is the public reference for measuring liquid flow in closed conduits by the weighing method, static or dynamic. ISO/IEC 17025 is the public reference for the competence of calibration laboratories. Neither sets the flow range, the accuracy class or the liquid for a particular site: that is set by the customer against their own meters, and this page prints none of it. Accreditation of a laboratory rests with the customer and their assessors; none is claimed here
Configurations	A master-meter stand with a reference meter beside the meter under test, a gravimetric rig with a diverter, weighing tank, scale and clock, and a combined rig whose weighing tank proves its own master meters
Scope Boundary	This is the rig that calibrates a flow meter or flow sensor against a weighing or master-meter reference. It is not a bench that tests a component's flow (see aerospace nozzle flow test bench), not a flow meter (see CNG gas flow meter), and not a pressure calibration bench (see pressure calibration bench)
Status	Neometrix has quoted against successive flow calibration rig and flow test rig requirements, and no delivered flow calibration rig is claimed.

Configurations

One method, three ways to supply the rig.

The method, the record and the cleanliness rules are shared. What changes is the reference and the size of the rig.

Master-meter stand

Shop floor and field

A reference meter in line beside the meter under test, sharing the flow, for quick routine checks.

Gravimetric rig

The weighing reference

A diverter, a weighing tank, a scale and a clock, for the highest class of comparison.

Combined rig

Weighing and master meters

A weighing tank that proves its own master meters, so one site keeps a traceable reference of its own.

Fig · 06 — Three ways to supply the rig, one method: a master-meter stand, a gravimetric rig, or a combined rig.

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

Where it is used

Wherever a flow reading has to be believed.

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

Plant and process meters

Where the flow meters on a plant or a test rig are checked against a known quantity of liquid before they are trusted.

Fuel and oil systems

Where the flow sensors on fuel and oil systems are checked on a schedule.

Calibration laboratories

Where a weighing reference is kept, and master meters are proved against it.

After a repair or a doubtful reading

Where a meter that has been repaired, 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 weighing the reference for liquid flow?

Because a meter cannot check itself. In the weighing method, a quantity of liquid is collected in a tank on a scale over a timed interval, and the flow is the mass divided by the time. Mass and time can each be measured on their own and traced back to national standards, so the result does not depend on trusting any other flow meter. ISO 4185 is the public standard for measuring liquid flow in closed conduits by weighing, and weighing is generally the method against which master meters are themselves proved.

Q · 02 Why does the flow keep running instead of stopping to fill the tank?

The weighing method can be run two ways. In the static way the flow is started and stopped into an empty tank. In the flying way the flow runs all the time and a diverter swings it into the tank and away again. The flying way keeps the flow steady for the meter, at the price of a timing error from the diverter, which has to be measured and kept small. The static way avoids the diverter, at the price of start and stop transients. Which is right depends on the meter's size, its range and the class of accuracy wanted, and this page does not pick one for you.

Q · 03 What do buoyancy, density and temperature have to do with it?

A scale reads weight, not mass, and the air around the liquid lifts it a little, so the reading is corrected for the buoyancy of air to give the true mass. Many meters report volume, so the density of the liquid is needed to move between mass and volume, and density depends on temperature, so the temperature is measured where the liquid is and noted with every run. Leaving either out gives a calibration that looks precise and is quietly biased.

Q · 04 Is this the same as the nozzle flow bench, the flow divider bench, the CNG flow meter or the pressure calibration pages?

No, and the differences are worth stating precisely. The aerospace nozzle flow test bench page validates the flow of aviation nozzles and oil jets to an aerospace standard, and the multi-port flow divider test bench page qualifies flow dividers, so both test a component's flow. The CNG gas flow meter page is an orifice-plate gas flow measurement system, so it is a meter. The pressure calibration bench page is the same calibration discipline applied to pressure. This page does not replace any of them, and it does not claim what they claim a second time.

Q · 05 What can a rig not do?

It measures a meter's error; it does not remove it. A meter that fails is adjusted or repaired separately, and the rig then proves the result. This page is about liquid flow: gas flow needs different references, and none is claimed here. How good the comparison is depends on the class of the reference, on a steady flow, and on a clean, degassed liquid. 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 flow calibration rig and flow test rig requirements, and no delivered flow calibration rig is claimed. What stands behind the offer is adjacent: Neometrix engineers recirculating fluid loops with flow data acquisition and component flow test benches (see the aerospace nozzle flow test bench and multi-port flow divider test bench pages). The scale and load cells, the master meters and the diverter actuator are specialist catalogue items, bought in, not invented. What Neometrix engineers is the rig around them: the flow source, the tank, the pipework, the diverter installation, the test lines, the data acquisition, the procedure and the records. So the honest position is that the rig is engineered to order, the neighbouring disciplines are in the building, and the first rig of this exact kind will be built around the customer's own meters and liquid rather than lifted off a shelf.

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

ISO 4185 is the public reference for measuring liquid flow in closed conduits by the weighing method, static or dynamic. ISO/IEC 17025 is the public reference for the competence of calibration laboratories. Neither names the flow range, the accuracy class or the liquid a particular site must cover: that is set by the customer against their own meters and the decisions that rest on them, and this page prints none of it. Acceptance of the finished rig, including its proving runs 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 meters rather than the rig. First, the meters: their types and sizes, and how many are checked in a day. Second, the flow range they cover. Third, the accuracy class you need, which sets the class of the reference. Fourth, the liquid: water, oil, fuel or something else, and how clean it must be. Fifth, the configuration: a master-meter stand, a gravimetric rig or a combined rig. Sixth, the site: the floor, the power, the supply and drain for the liquid, 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 flow and calibration pages, and how they differ from this one.

Three neighbours: a component test, a meter, and a sister calibration page.

↗ A component's flow

Aerospace Nozzle Flow Test Bench

Validates the flow of aviation nozzles and oil jets to an aerospace standard - it tests a nozzle, it does not calibrate a meter.

↗ A meter, not a rig

Greenfuel-CNG Gas Flow Meter

An orifice-plate gas flow measurement system - a meter, not a rig that calibrates one.

↗ Another quantity

Pressure Calibration Bench

The same calibration discipline for pressure: a reference, a steady hold, and an as-found, as-left record.

Browse all Neometrix product lines.

Get a quotation

Tell us the meters, the flow range,
and the liquid.

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 — flow calibration rig Capability sheet (PDF) +91 7777 876 876

ISO 9001 / 14001 ENGINEERED-TO-ORDER CLASS — FLOW CALIBRATION RIG SET UP · SETTLE · DIVERT · COLLECT · COMPARE · RECORD — THE METER IS JUDGED AGAINST MASS AND TIME ENGINEERED IN NOIDA · INDIA