Neometrix / Gas Systems / Gas Mixing System / NMX-GMS-83

NMX-GMS-83 · ENGINEERED-TO-ORDER CLASS — SPECIFY · SIZE · BUILD · CALIBRATE · RUN · PROVE

Gas Mixing System. Set the flows; prove the mix.

Name: Gas Mixing System
Brand: Neometrix
SKU: NMX-GMS-83

A gas mixing system blends pure gases into a mixture of a known composition, continuously, for a laboratory, a process or a calibration. Each gas flows through its own mass-flow controller, the flows are set in the ratio the recipe needs, and an analyser checks the blend.

So the system has to set every flow against the right gas, hold the pressure steady, and prove the mix with an analyser before anyone trusts it.

Discuss a gas mixing system Capability note (PDF)

A gas mixing panel on a plain white studio background: a pale grey steel frame holding a stainless steel back plate, on which a row of four stainless mass-flow controllers with smooth black electronics housings are joined by thin stainless tubes to a manifold, a stainless mixing vessel and an outlet valve, two inlet lines at the left each passing through a small valve and a regulator body, black cables running to a grey junction box at the right, and no people

Fig · 01 — A gas mixing system: four mass-flow controllers on one panel, their outlets joined at a manifold that leads to a mixing vessel and an outlet valve — illustrative render.

The result

a mixture of known compositionrecipe, flows and analysed result

The flows

one controller for each gasset in the ratio the recipe needs

The gas

each controller set for its ownor given its correction factor

The proof

an analyser on the outletchecked against reference mixtures

Status

engineered to orderno delivered mixer claimed

ISO 9001ISO 14001ISO 6145-7 reference standard

Overview

Why the whole job is the ratio.

Because a mixture is a ratio of flows, so its accuracy is the accuracy of the flows, and the flows are only as good as the controllers, the gas and the pressure.

A mass-flow controller assembly on a plain white studio background: a stainless steel block with a compression fitting at each end and a smooth black cylindrical electronics housing on top with a short black cable, a small shut-off valve with a straight lever ahead of the inlet, and a small stainless base block, and no people

Fig · 02 — One mass-flow controller assembly: a stainless block with its electronics housing, an inlet and an outlet fitting and a shut-off valve ahead of it — illustrative render.

Set the flows; prove the mix.

What the system is for

It blends pure gases, or a stock mixture and a diluent, into a mixture of a known composition, continuously. It suits a blending panel for a few gases, a dilution system for very small fractions, and a hazardous-gas blending cabinet. The blend feeds an instrument, a process or a test, and an analyser checks it.

Why a mixture is a ratio of flows

Each gas flows through its own controller, and the fraction of a gas is its flow divided by the total flow. So the mix is only as true as the flows. A gas that is a small part of the blend runs at the bottom of its controller's range, where the error is greatest in proportion. So a small fraction is made in two steps, from a stock mixture, and not from a pure gas at a trickle.

Why each controller is set for its own gas

A thermal mass-flow controller senses flow by how the gas carries heat, and gases carry heat differently. A controller that is right for one gas reads wrongly on another, and the mixture is biased. So each controller is calibrated on the gas it flows, or given the correction factor for it, and the recipe is written for that.

Why the pressure is held steady

The flow through a controller depends on the pressure across it. If a supply or the outlet pressure shifts, the flows shift with it, and not equally. So every gas comes through a regulator and the outlet pressure is held, and the blend does not change when the user's end does.

Why the blend is given time

Gases do not mix the instant they meet. The blend passes through a mixing vessel, the lines have to be cleared of the last recipe, and the flows have to settle before the composition is steady. The system waits, and it records how long it waited.

Why an analyser proves it

A controller sets a flow. It does not read a composition. Only an analyser does, and a blender that is never checked against one can be wrong in a steady, believable way. So the outlet is analysed against reference mixtures, and the difference is recorded with the recipe.

Why the safety is part of the mixing

Mixed gases can be flammable, oxidising or toxic in ways the pure gases are not. The system keeps incompatible gases apart until the mixing point, clears the lines between recipes, detects leaks, and shuts every gas off if one is lost. Where a blend could be flammable, the recipe is checked before it runs.

The method

Specify, size, build, calibrate, run, and prove.

Six steps in a fixed order. Showing that the flows settle and that the analyser reads the recipe are the two a quick order skips.

1 · Specify

The gases, the mixtures wanted, the flow and pressure at the outlet, the accuracy and the analyser are stated by the customer.

2 · Size

Each controller is sized for the flow its gas has to carry in every recipe, so that none runs at the bottom of its range, and the mixing vessel for the time the blend needs.

3 · Build

The panel, the regulators, the controllers, the tubing, the mixing vessel, the outlet and the controls are built as one system.

4 · Calibrate

Each controller is calibrated on its gas or given its correction factor, and the analyser is calibrated against reference mixtures, so that every reading has a record of its own.

5 · Run

A trial blend is run first, to show that the flows settle, that the analyser reads the recipe and that the system shuts down safely when a gas is lost.

6 · Prove

A record is kept for every blend, with its recipe, its flows, its pressure and its analysed composition, and handed over with the system.

Which blend, which approach

Blend	What it needs	What to watch
A few gases at comparable fractions	a controller for each gas, each in the comfortable part of its range	the range of each controller, the correction factor of each gas and the settle
A small fraction of one gas	two steps, from a stock mixture and a pure diluent, not a pure gas at a trickle	a controller at the bottom of its range gives the greatest error in proportion
Gases that react or oxidise	the gases kept apart until the mixing point, with the lines cleared between recipes	the materials, the cleanliness and the order in which the gases are opened
Flammable or toxic gases	a ventilated cabinet with detection and interlocks	leaks, the loss of a gas, and a blend that could itself be flammable
Proof of the blend	an analyser on the outlet and reference mixtures to check it against	the analyser's own calibration and how fast it responds

The step people underrate is the analyser. A blender with no analyser gives a mixture that is believed, not one that is known.

Work content

What the system contains, element by element.

Read it as a checklist: a system missing a row will make a mixture, but not one you can say the composition of.

A mixing vessel and outlet on a plain white studio background: an upright stainless steel cylindrical vessel with domed ends in front of a pale grey support on a grey base plate, a stainless manifold block above it with four thin tubes looping up into its top fittings, and an outlet tube running to a plain cylindrical regulator body and a small valve with a quick-connect fitting, and no people

Fig · 03 — A mixing vessel and outlet: four inlet tubes joined at a manifold block above the vessel, and an outlet through a plain regulator body to a sample valve with a quick-connect fitting — illustrative render.

Element	What it does	What matters
Gas inlets and regulators	bring in each gas at a steady pressure	a regulator, a filter and a shut-off for every gas, with the gas named at its connection
Mass-flow controllers	set each flow	a controller for each gas, calibrated on that gas or given its correction factor, and in the comfortable part of its range
Manifold and tubing	carry and join the gases	clean stainless tubing, leak-tight fittings, no dead legs that hold the last recipe, and incompatible gases kept apart
Mixing vessel	blends the gases	a volume that gives the blend time to become even before it leaves
Pressure control and outlet	hold the outlet steady	a back-pressure arrangement and a sample port, so that the blend does not change when the user's end does
Analyser connection	proves the blend	a sample line to an analyser, reference mixtures, and a valve to switch between them
Gas detection and interlocks	keep it safe	leak detection, a shut-off on every gas, and a stop that closes them all when one is lost
Purge	clears the last recipe	a purge gas and a sequence that runs before and after each blend
Controller and software	run the recipes	recipes with ramps, a settle before the blend is released, a log of flows, pressures and composition, and a record for every blend
Procedure	fixes the sequence	specify, size, build, calibrate, run and prove, the same for every system
Testing & documentation	prove the system first	a trial blend, the flows shown to settle, the analyser shown to read the recipe, and a record the customer can inspect

The elements that decide whether the blend is true are the controllers and the analyser connection, and the one that decides whether it stays true is the pressure control. The first two make the mix and prove it, and the third keeps it from drifting.

Full specification — expand

System	A regulator, a filter and a shut-off for every gas; a mass-flow controller for each gas, calibrated on that gas or given its correction factor; clean stainless tubing and a manifold with no dead legs, keeping incompatible gases apart; a mixing vessel; a back-pressure arrangement and a sample port at the outlet; a sample line to an analyser with reference mixtures; gas detection, a shut-off on every gas and interlocks; a purge sequence; a controller and software that run recipes and write a record for every blend; a written test plan; and calibration, testing and documentation before handover
The One Idea	Set the flows; prove the mix.
Why A Mixture Is A Ratio Of Flows	The fraction of a gas is its flow divided by the total flow, so the mix is only as true as the flows, and a gas that is a small part of the blend runs at the bottom of its controller's range, where the error is greatest in proportion, so a small fraction is made in two steps from a stock mixture
Why Each Controller Is Set For Its Own Gas	A thermal mass-flow controller senses flow by how the gas carries heat, and gases carry heat differently, so a controller that is right for one gas reads wrongly on another and biases the mixture unless it is calibrated on its own gas or given the correction factor
Why The Pressure Is Held Steady	The flow through a controller depends on the pressure across it, so every gas comes through a regulator and the outlet pressure is held, so that the flows do not shift when the user's end changes
Why An Analyser Proves It	A controller sets a flow and does not read a composition, so a blend that is not checked against an analyser can be wrong in a steady and believable way, and the outlet is analysed against reference mixtures and the difference recorded with the recipe
Standards	ISO 6145-7 is the public standard for preparing calibration gas mixtures continuously with thermal mass-flow controllers. This page prints none of its limits, uncertainties or tolerances, and no edition year: those come from the method the customer names and from the gases. Approval of a mixture, or of a system, rests with the customer and the authority they name; none is claimed here
Configurations	A blending panel, a dilution system, and a hazardous-gas blending cabinet
Scope Boundary	This page is the gas mixing system. It is not a hypoxic gas generator, which mixes nitrogen and air to simulate altitude (see hypoxic gas generators), not a gas distribution system, which delivers pure gases to laboratory panels (see gas distribution system) and not a special gas boosting system, which compresses and fills poisonous, flammable and mixed gases into cylinders (see special gas boosting system). A gas analyser and a calibration gas cylinder are different equipment again. No certification is claimed here
Status	Neometrix engineers gas mixing systems to order, and no delivered gas mixing system is claimed.

Configurations

One method, three ways to build the system.

The method, the controllers, the pressure control, the analyser connection and the record are shared. What changes is how many gases are blended, how small the smallest fraction is, and how hazardous the gases are.

Blending panel

A few gases, one mixture at a time

A controller and a regulator for each gas on one panel, joined at a manifold and a mixing vessel, for a laboratory or a process that needs a mixture of a few gases at comparable fractions.

Dilution system

Very small fractions, made in two steps

A stock mixture and a pure diluent, each through a controller in the comfortable part of its range, so that a very small fraction is never made from a pure gas at a trickle.

Hazardous-gas blending cabinet

Flammable and toxic gases, ventilated and interlocked

The blending panel inside a ventilated cabinet, with leak detection, a shut-off on every gas, a purge and an interlock that stops all of it when one gas is lost.

And the part that is not equipment at all, yet decides all three: the recipe and the test plan. They fix the gases, the order they are opened in, the settle before a blend is released, the analyser check and what is recorded. They are written from the customer's own gases and method, not from the panel.

The drawings

A reference set, drawn as real CAD sheets.

Four sheets of one reference configuration: the process schematic, the panel arrangement, six construction details, and the hazardous-gas cabinet. They show how the system goes together and what it does when something goes wrong. They carry tags and arrangement only. Every flow, pressure, composition, time and size is fixed by design for the customer's gases and method.

Reference drawing sheet one, the process schematic of a four-gas blending panel with a purge line. Each gas line runs left to right through a hand valve, a filter, a pressure regulator, a mass-flow controller with its flow-controller tag, a solenoid shut-off valve and a check valve into one manifold. The manifold feeds a mixing vessel with a relief valve and a pressure transmitter. The outlet passes a back-pressure regulator, a sample tee to a gas analyser with a vent, and an outlet valve to the user. A blend controller and an interlock logic box tie to the controllers and the shut-off valves by dashed signal lines, with a gas detector and an extraction flow switch as inputs. A legend, ten notes and a title block stamped reference configuration, not for construction

Fig · 04 — Sheet 01, the process schematic: four gas lines and a purge, the manifold, the vessel, the sample point and the interlock logic. Reference configuration, tags only.

Reference drawing sheet two, the panel general arrangement. A front elevation of a framed back plate carries five gas lines from left to right, each with an inlet bulkhead, a hand valve, a filter, a regulator, a mass-flow controller with a plain housing, a solenoid shut-off valve and a check valve, then a vertical manifold, a mixing vessel with a relief valve, a back-pressure regulator, a sample valve and an outlet bulkhead, with cable trunking and a junction box. Overall dimensions are marked with the letters A, B and C, a side view shows the depth, and a table lists sixteen numbered items

Fig · 05 — Sheet 02, the panel arrangement, drawn line for line from the schematic, with a side view and an item list. Reference configuration, sizes set by design.

Reference drawing sheet three, six construction details. The first shows a mass-flow controller assembly with its shut-off valve, compression fittings, base block and gas tag. The second shows a manifold header with a dead leg crossed out beside a swept header with nothing capped. The third shows the mixing vessel with its inlet, outlet, transmitter, relief and drain ports. The fourth shows the outlet with the back-pressure regulator, sample tee and sample valve. The fifth shows the gas inlet group through a wall. The sixth shows a tube clamp in section on a back plate

Fig · 06 — Sheet 03, six details: the controller assembly, the swept manifold, the vessel connections, the sample point, the inlet group and the tube clamp. Reference configuration.

Fig · 07 — Sheet 04, the hazardous-gas cabinet: the plan, the six-step sequence and the table of trips. Reference configuration.

Every real system is drawn for its own gases, room and method. These sheets are the arrangement, the details and the order of work that a project set starts from. Approval of any drawing rests with the customer and the authority they name; none is claimed here.

PDF · four sheets

Reference drawing set — schematic, arrangement, details, cabinet

PDF · capability sheet

Gas mixing system — what Neometrix engineers

Where it is used

Wherever a gas has to be a known mixture.

The common thread is a gas whose composition a result depends on, and a blend that has to be shown to be what the recipe says.

Calibration and reference laboratories

Where calibration gas mixtures are prepared and checked against reference mixtures.

Process and materials development

Where a process, a coating or a material is tried in a controlled atmosphere of chosen composition.

Sensor and detector testing

Where a gas sensor or detector is exposed to known mixtures to see how it responds.

Research and teaching laboratories

Where experiments need a repeatable atmosphere and students learn what a blend really is.

Watch

See it in motion.

A short walkthrough video of the gas mixing system.

FAQ

Common questions.

Longer answers, for readers who want the reasoning.

Q · 01 What does a gas mixing system actually do?

It blends pure gases, or a stock mixture and a diluent, into a mixture of a known composition, continuously. Each gas comes through a regulator and its own mass-flow controller, the flows are set in the ratio the recipe needs, the gases join at a manifold and pass through a mixing vessel, and the outlet pressure is held. An analyser on the outlet checks the blend, and the system records the recipe, the flows and the result for every blend. It does not decide what a mixture is for or whether it is acceptable: that is the job of the method and of the people who name it.

Q · 02 Why does each controller have to be set for its own gas?

Because a thermal mass-flow controller senses flow by how the gas carries heat, and different gases carry heat differently. A controller that is right for one gas reads wrongly on another, and if the difference is ignored the mixture is biased, steadily and without any alarm. The answer is to calibrate each controller on the gas it flows, or to apply the correction factor for that gas, and to write the recipe with it. The correction is an approximation for most gases, which is one more reason the outlet is analysed. We set the controllers against your gases, and the factor in use goes into the record.

Q · 03 How is a very small fraction of a gas made?

In two steps, and not from a pure gas at a trickle. A controller is least accurate in proportion at the bottom of its range, so a gas that is a very small part of the blend would carry the greatest error. Instead the gas is bought already diluted, as a stock mixture, and that mixture is blended with a pure diluent through controllers that both run in the comfortable part of their ranges. Two stages can reach a fraction that one could not. We size the controllers against the smallest fraction you need, and the dilution system is the configuration built for it.

Q · 04 Why does the blend need an analyser, when the controllers already know the flows?

Because the controllers set the flows, and the flows are not the composition. Each controller has its own error, a gas correction can be imperfect, a supply pressure can drift, and a blend that has not settled is not yet the mixture. A published study of a blender built on mass-flow controllers found a steady bias that showed only when the blend was compared with reference mixtures by analysis. An analyser on the outlet, itself calibrated against reference mixtures, is what turns a mixture that is believed into one that is known. We connect the analyser, fit a valve to switch between the blend and the reference mixtures, and record the difference.

Q · 05 Is this the same as the hypoxic gas generator, the gas distribution system or the special gas boosting system?

No, and the differences are worth stating precisely. The hypoxic gas generator page covers mixing nitrogen and air to simulate altitude, one blend for one purpose. The gas distribution system page covers delivering pure gases to laboratory panels. The special gas boosting system page covers compressing and filling poisonous, flammable and mixed gases into cylinders. This page is the gas mixing system, which blends gases to a recipe and proves the blend. It is not a hypoxic gas generator, not a gas distribution system and not a special gas boosting system, and it does not claim what they claim a second time.

Q · 06 Has Neometrix built one of these?

We would rather answer this plainly than let a page imply otherwise. Neometrix engineers gas mixing systems to order, and no delivered gas mixing system is claimed. What stands behind the offer is adjacent: Neometrix engineers a hypoxic gas generator (see the hypoxic gas generator page), a gas distribution system (see the gas distribution system page) and a special gas boosting system (see the special gas boosting system page). The mass-flow controllers, regulators, valves, analysers, detectors and logic controllers are catalogue items, bought in, not invented. What Neometrix engineers is the system around them: the panel, the tubing and manifold, the mixing vessel and outlet, the interlocks and purge, the software and the procedure. So the honest position is that the system is engineered to order, the neighbouring disciplines are in the building, and the first system of this exact kind will be built around the customer's own gases rather than taken off a shelf.

Q · 07 Which standard applies, and what can the system not do?

ISO 6145-7 is the public standard for preparing calibration gas mixtures continuously from pure gases or mixtures with thermal mass-flow controllers. It is written for gases that do not react with each other, and it treats the controller's flow reading as something to be calibrated independently, not trusted as absolute. This page prints none of its limits, uncertainties or tolerances, and no edition year: those come from the method the customer names and from the gases. The system blends and keeps a record. It does not make a mixture certified and it does not approve a gas for use: this page claims no certification or accreditation. No flow, pressure, composition, time, size or quantity figure is printed here, and approval for use rests with the customer and the authority they name; none is claimed here.

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

Six things, and most of them describe your gases rather than the system. First, the gases: which they are, how they are supplied, and whether any is flammable, oxidising or toxic. Second, the mixtures: the recipes you need and the smallest fraction in any of them. Third, the outlet: the flow and the pressure the blend must be delivered at. Fourth, the proof: the analyser you have or want, and the reference mixtures you can supply. Fifth, the room: whether the system stands on a laboratory bench or needs a ventilated cabinet. Sixth, the record: what you want kept for every blend. From that we come back with a system concept, a written test plan you can check, and a budgetary price.

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

Three neighbours: one makes a single special blend, one delivers pure gases, one compresses and fills.

↗ Altitude

Hypoxic Gas Generators

Mixes nitrogen and air to simulate altitude - one blend for one purpose, where this page blends gases to any recipe and proves the blend.

↗ Pure gases

Gas Distribution System

Delivers pure gases from their source to laboratory panels - the supply of single gases, where this page combines them into a mixture.

↗ Boosting and filling

Special Gas Boosting System

Compresses and fills poisonous, flammable and mixed gases into cylinders - moving and storing gas, where this page makes the mixture.

Browse all Neometrix product lines.

Get a quotation

Tell us the gases,
and how true the mix must be.

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

Enquire — gas mixing system Capability sheet (PDF) +91 7777 876 876

ISO 9001 / 14001 ENGINEERED-TO-ORDER CLASS — GAS MIXING SYSTEM SPECIFY · SIZE · BUILD · CALIBRATE · RUN · PROVE — SET THE FLOWS; PROVE THE MIX ENGINEERED IN NOIDA · INDIA