Neometrix / Gas Handling Equipment / Gas Charging Trolley / NMX-GCT-95

NMX-GCT-95 · ENGINEERED-TO-ORDER CLASS — DUTY · CIRCUIT · MATERIALS · FRAME · BUILD · PROVE

Gas Charging Trolley. Right gas, right pressure.

Name: Gas Charging Trolley
Brand: Neometrix
SKU: NMX-GCT-95

A gas charging trolley carries cylinders on wheels to the system that needs charging: a manifold, a regulator, a relief valve, gauges and a hose join the cylinders to it, and the system is charged where it stands. Neometrix engineers it as a system around the duty: the circuit, the materials and their cleaning, the frame, the hose stowage and the proof.

So the trolley has to deliver only the gas that was asked for, at the pressure that was set and no higher, and use every cylinder as far as it can.

Discuss a charging trolley Capability note (PDF)

A four-cylinder gas charging trolley on a plain white studio background: a pale grey tubular steel frame on four black wheels with a long push handle, four plain unlabelled pale grey cylinders standing upright in a cradle held by a bright chain, a bright steel manifold across the top with four valves with plain black handles, a pressure regulator with a black knob, two round gauges turned away, a coiled braided stainless hose with a bright coupling hanging on a hook, and no people

Fig · 01 — A four-cylinder gas charging trolley: four cylinders in a cradle on a wheeled frame, a manifold with a valve for each, a regulator and gauges, and a hose hung on its hook — illustrative render.

The result

a system charged with the right gasat the pressure that was set, and no higher

The cylinders

used in order, least pressure firstso that the gas in every cylinder is put to use

The outlet

one gas, one couplingso that the wrong gas cannot be joined

The oxygen

cleaned, oil-free, opened slowlyevery part kept clean between uses

Status

engineered to orderno delivered trolley claimed

ISO 9001ISO 14001ISO 5145 reference for cylinder valve outletsCGA G-4.1 reference for oxygen cleaning

Overview

What a charging trolley has to get right, and what goes wrong when it does not.

Because the gas, the pressure and the cleanliness are all decided at the moment of charging, and a mistake in any one of them is hard to undo.

The control group of a gas charging trolley on a plain white studio background: a bright steel manifold block with four valves with plain black round handles, a pressure regulator with a black knob, a relief valve with a spring cap, two round gauges turned away, bright stainless tubes, and a coiled braided stainless hose ending in a bright coupling, and no people

Fig · 02 — The control group: a manifold with a valve for each cylinder, a regulator, a relief valve, gauges, and the hose with its coupling — illustrative render.

Right gas, right pressure.

What the trolley is for

It charges a system from cylinders where the system stands. It carries the cylinders on wheels, joins them to a manifold, sets the pressure with a regulator, and delivers the gas through a hose. It serves flight-line and workshop servicing, hangars, laboratories and industrial plants.

Why the cylinders are used in order

A system fills until its pressure equals the cylinder's. So the cylinder with the least pressure that can still add pressure is used first, then the next, and the last cylinders top it up. In that order the gas in every cylinder is put to use.

Why each gas has its own outlet

Each gas has its own outlet and coupling, so that a nitrogen hose cannot be joined to an oxygen port. ISO 5145 covers the selection of cylinder valve outlet connections, and its aim is to prevent the interconnection of incompatible gases.

Why a regulator and a relief valve

The cylinder is at a far higher pressure than the system accepts. A regulator sets the charging pressure, and a relief valve opens if the regulator fails, so that the system is never charged above the pressure it can take.

Why oxygen is different

Oxygen makes a fire worse. Oil, grease and dirt can burn in it, and a valve opened fast can heat the gas by compression enough to start a fire. So oxygen service parts are cleaned and kept clean, the lines are oil-free, and the valves open slowly. CGA G-4.1 covers cleaning equipment for oxygen service.

Why each cylinder has its own valve and gauge

A valve for each cylinder lets one be shut off and changed while the others stay in use. A contents gauge for each one shows how much is left, so that the order of use is chosen from what the gauges say.

Why the hose is part of the safety

A hose can hold pressure after the valves are shut. So a vent valve relieves it before the hose is disconnected, the coupling fits only its own gas, and the hose has a place on the frame where it is protected.

Why the frame matters

A cylinder that falls is a hazard. So the cylinders stand in a cradle held by a chain or a strap, the valves are protected from knocks, the weight sits low, and the trolley has a brake and a handle that let it be wheeled safely.

The method

Duty, circuit, materials, frame, build and prove.

Six steps in a fixed order. The materials and the proof are the two that a quick job skips.

1 · Duty

The gas, the pressure the receiving system accepts, the number of cylinders, how far the trolley is wheeled and over what ground are noted, with what is to be charged and how often.

2 · Circuit

The manifold, the valves, the regulator, the relief valve, the gauges, the vent and the hose are laid out, and the relief setting is chosen below what the receiving system can take.

3 · Materials and cleaning

The metals and seals are chosen for the gas. For oxygen they are oxygen-compatible, and every part that touches the gas is cleaned and sealed for oxygen service.

4 · Frame

The frame, the cradle, the restraint, the wheels and brake, the handle and the hose stowage are designed so that the cylinders are held and the trolley is stable.

5 · Build

The frame, the manifold and the circuit are built from clean parts, with each fitting matched to its line and each gas kept on its own pipework.

6 · Prove

The circuit is leak tested, the relief and regulator settings are proved, the cleanliness is recorded for oxygen, and the record is handed over with the trolley.

Which hazard, which safeguard

What can go wrong	Why it happens	What the trolley does about it
The wrong gas is connected	two couplings fit one another	a coupling and an outlet that fit one gas only, and lines kept and marked for their own gas
The system is charged too high	the regulator sticks or is set wrongly	a relief valve set below the pressure the system can take, and a charging gauge to read it
A fire in oxygen service	oil, dirt or a fast-opening valve	parts cleaned for oxygen, oil-free lines, valves that open slowly, and a trolley kept sealed between uses
A cylinder falls or is knocked	it is not held, or the trolley tips	a cradle with a chain or strap, protected valves, a low weight and a brake
Pressure is trapped in the hose	the valves are shut but the hose is full	a vent valve that relieves the hose before it is disconnected
Gas is lost to a leak	a joint or a seal is poor	joints proved by a leak test, and contents gauges that show a loss at once

The step people underrate is the cleaning for oxygen. A trolley that is built well and then handled with an oily hand is no longer a trolley for oxygen.

Work content

What the trolley contains, element by element.

Read it as a checklist: a trolley missing a row will carry gas, but it will not keep the right gas at the right pressure.

A single-cylinder gas charging trolley on a plain white studio background: a pale grey two-wheeled tubular steel hand trolley with a single plain unlabelled pale grey cylinder standing upright and held by a bright strap, a regulator with a black knob and two round gauges turned away on a bright steel block at the cylinder top, and a coiled braided stainless hose with a bright coupling hanging from a hook on the frame, and no people

Fig · 03 — A single-cylinder trolley: one cylinder strapped to a hand trolley, a regulator and gauges at the top, and the hose on its hook — illustrative render.

Element	What it does	What matters
Frame and wheels	carry the cylinders	a rigid tubular frame with wheels and a brake, a handle, and a low weight so that the trolley does not tip
Cradle and restraint	hold the cylinders	a cradle that locates each cylinder and a chain or strap that holds it, so that none can fall or shift
Manifold and valves	join the cylinders	a manifold with an isolation valve for each cylinder, so that one can be shut off and changed while the others stay in use
Contents gauges	show what is left	a gauge for each cylinder, so that the order of use is chosen from what the gauges say
Regulator	sets the charging pressure	a regulator that brings the cylinder pressure down to the pressure the system accepts, steady while the cylinder empties
Relief valve	protects the system	a relief valve set below what the receiving system can take, so that a failed regulator cannot overcharge it
Charging gauge	shows the pressure given	a gauge on the outlet side, so that the pressure going into the system is read and not assumed
Vent valve and filter	relieve and protect	a vent that relieves the hose before it is disconnected, and a filter that keeps particles out of the regulator and the system
Hose and coupling	deliver the gas	a braided hose with a coupling that fits one gas only, stowed on the frame where it is protected
Materials and cleaning	keep the gas safe	metals and seals chosen for the gas, and for oxygen oxygen-compatible, cleaned for oxygen service, oil-free, and sealed against dirt between uses
Identification	name the gas	the gas marked on the frame and on the lines, so that the trolley cannot be mistaken for another
Testing & documentation	prove the trolley first	leak tests, the relief and regulator settings proved, the cleanliness recorded for oxygen, and a record the customer can inspect

The elements that decide the result are the gas-specific coupling and the relief valve, and the one that decides whether it is safe for oxygen is the cleaning. The first two keep the wrong gas and the wrong pressure out, and the third keeps a fire out.

Full specification — expand

System	A wheeled frame with a cradle and restraints for the cylinders; a manifold with an isolation valve and a contents gauge for each cylinder; a pressure regulator and a relief valve; a charging gauge; a vent valve and a filter; a charging hose with a gas-specific coupling, stowed on the frame; materials and cleaning chosen for the gas; and leak testing and documentation before handover
The One Idea	Right gas, right pressure.
Why The Cylinders Are Used In Order	A receiving system fills until its pressure equals the cylinder's, so the cylinder with the least pressure that can still add pressure is used first, then the next, and the last cylinders top it up; this uses the gas in every cylinder as far as it can be used
Why Oxygen Is Different	Oxygen makes a fire worse: oil, grease and dirt can burn in it, and a valve opened fast can heat the gas by compression enough to start a fire, so oxygen service parts are cleaned and kept clean, the lines are oil-free and the valves open slowly
Standards	ISO 5145 covers the selection of cylinder valve outlet connections, to prevent the interconnection of incompatible gases, and CGA G-4.1 covers cleaning equipment for oxygen service. This page prints none of their requirements, and no edition year: those come from the standard the customer names. Approval of a trolley rests with the customer and the authority they name; none is claimed here
Configurations	A single-cylinder trolley, a four-cylinder cascade trolley, and an oxygen-service trolley
Scope Boundary	This page is the gas charging trolley, which carries cylinders and charges a system from them. It is not a booster trolley, which raises a gas above the cylinder pressure (see portable single cylinder nitrogen trolley with booster), not a complete oxygen system, which charges, distributes and tests aircrew oxygen (see aircraft oxygen system) and not a tyre charging rig, which fills a tyre to a set pressure (see aircraft tyre nitrogen charging rig). It does not decide the charging pressure of the system it charges, and it does not replace the operator's own procedure. No certification or accreditation is claimed here
Status	Neometrix has quoted against successive gas charging trolley requirements, and no delivered gas charging trolley is claimed.

Configurations

One method, three ways to build the trolley.

The method, the safety design, the materials logic and the proof are shared. What changes is how many cylinders the trolley carries, and how much the gas asks of the parts.

Single-cylinder trolley

One cylinder on a hand trolley, with a regulator, gauges and a hose

For charging at a point of use: one cylinder strapped to a light trolley, a regulator and a charging gauge at its valve, and a hose that fits one gas only.

Four-cylinder cascade trolley

A manifold with a valve and a contents gauge for each cylinder, a regulator and a relief valve

For a system that takes more gas than one cylinder holds: cylinders used in order, least pressure first, through a manifold, with the charging pressure set and protected.

Oxygen-service trolley

Oxygen-compatible parts, cleaned for oxygen service, oil-free and sealed between uses

For oxygen: materials and seals chosen for it, every wetted part cleaned and sealed, valves that open slowly, and a record of the cleaning that goes with the trolley.

And the part that is not equipment at all, yet decides all three: the duty and the cleaning plan. They are written from the customer's own gas, system and handling, not from the trolley.

The drawings

A reference set, drawn as real CAD sheets.

Two sheets of one reference configuration: the gas circuit of a four-cylinder gas charging trolley, and its general arrangement with three details. They show the cylinders with their valves and gauges, the manifold, the regulator and the relief valve, the hose and its coupling, the trolley in elevation and plan, the order of use of the cylinders and the restraint. They carry tags and letters only. Every pressure, flow, size, capacity and quantity is fixed by design for the customer's duty.

Reference drawing sheet one, the gas circuit of a four-cylinder gas charging trolley. Four gas cylinders, each with a hand valve and a contents gauge, join a manifold header that leads through a filter to a pressure regulator, with a charging gauge and a relief valve on the outlet side. A non-return valve, a vent valve, a hose and a gas-specific coupling lead to the system being charged. A legend, a table of what each step does, seven notes and a title block stamped reference configuration, not for construction

Fig · 04 — Sheet 01, the gas circuit: four cylinders with their valves and gauges, a manifold, a filter, a regulator, a relief valve, a vent valve, a hose and a gas-specific coupling, in the style of the graphical symbols of fluid power. Reference configuration, tags only.

Reference drawing sheet two, the general arrangement and details of a four-cylinder gas charging trolley. An elevation shows the chassis on its wheels, the handle, four cylinders held upright by a restraint strap, the manifold across their tops, the regulator and gauge panel, the hose reel and the hose with its coupling. A plan shows the four cylinders in one row with the strap round them. An item list numbers ten parts. Detail A shows the order of use of the cylinders, the least pressure first, Detail B a coupling that fits one gas only and Detail C the restraint of one cylinder. A title block stamped reference configuration, not for construction

Fig · 05 — Sheet 02, the general arrangement and details: the trolley in elevation and plan, the order of use of the cylinders, a coupling for one gas and the restraint. Reference configuration, letters only.

Every real trolley is drawn for its own gas, its own cylinders and its own duty. These sheets are the arrangement and the order of working that a project set starts from. Approval of any drawing rests with the customer and the authority they name; none is claimed here.

PDF · two sheets

Reference drawings — schematic and arrangement

PDF · capability sheet

Gas charging trolley — what Neometrix engineers

Where it is used

Wherever a system is charged from cylinders, and the gas has to be right.

The common thread is a system that has to be charged where it stands, a gas that cannot be mistaken for another, and a pressure that must not be exceeded.

Flight-line and ground servicing

Where aircraft systems are charged with nitrogen, air or oxygen at the aircraft, and the trolley is wheeled to the work.

Workshops and maintenance hangars

Where accumulators, struts and pneumatic systems are charged after overhaul, and one trolley serves many jobs.

Laboratories and test facilities

Where a test rig is charged with a clean gas at a set pressure, and the gas has to be known.

Industrial plants and back-up supply

Where a line or a process is charged or backed up from cylinders when the main supply is not available.

Watch

See it in motion.

A short walkthrough video of the Gas Charging Trolley.

FAQ

Common questions.

Longer answers, for readers who want the reasoning.

Q · 01 What does a gas charging trolley actually do?

It carries gas cylinders on wheels to a system that needs charging, and charges it where it stands. The cylinders stand in a cradle, held by a chain or a strap. A manifold joins them, with a valve and a contents gauge for each. A regulator brings the cylinder pressure down to the pressure the system accepts, a relief valve protects the system if the regulator fails, and a hose with a coupling that fits only its own gas delivers the gas. The trolley does not decide the charging pressure. That comes from the system being charged, and the trolley is built, set and proved to respect it.

Q · 02 Why are the cylinders used in order?

Because a system fills only until its pressure equals the pressure in the cylinder joined to it. If the cylinder with the highest pressure is used first, the system rises to that level and the cylinders with lower pressure can add nothing more. So the cylinder with the least pressure that can still add pressure is used first, then the next least, and the last cylinders top the system up. That is how a cascade uses the gas in every cylinder as far as it can be used. The contents gauge on each cylinder is what lets the operator choose the order, and the isolation valve on each lets one be shut off and changed while the others stay in service.

Q · 03 How is the wrong gas kept out?

By making the wrong connection impossible and not only forbidden. Each gas has its own outlet and its own coupling, so that a hose for one gas does not fit the port of another. ISO 5145 covers the selection of cylinder valve outlet connections, and its stated aim is to prevent the interconnection of incompatible gases. The trolley adds the rest: the lines are kept and marked for one gas, the gas is named on the frame, and a trolley built for oxygen is never used for another gas, because the cleaning that makes it safe for oxygen would be lost.

Q · 04 Why is oxygen treated differently?

Because oxygen makes a fire worse. Oil, grease and dirt can burn in it, and the gas itself can heat when a valve is opened fast, because the sudden rise of pressure compresses it in a dead end such as the inlet of a regulator, and that heat can be enough to start a fire. So the parts that touch oxygen are chosen for it, cleaned for oxygen service and sealed against dirt, the lines are oil-free, and the valves open slowly. CGA G-4.1 covers cleaning equipment for oxygen service. The cleaning is recorded and handed over with the trolley, because a trolley that has been cleaned and then handled carelessly is no longer clean.

Q · 05 Is this the same as a booster trolley, an oxygen system or a tyre charging rig?

No, and the differences are worth stating precisely. The portable single cylinder nitrogen trolley with booster page covers raising a gas above the pressure in the cylinder. The aircraft oxygen system page covers the whole system that charges, distributes and tests aircrew oxygen, on the ground and in the air. The aircraft tyre nitrogen charging rig page covers filling a tyre to a set pressure. This page is the gas charging trolley, which carries cylinders and charges a system from them. It does not replace any of them, 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 has quoted against successive gas charging trolley requirements, and no delivered gas charging trolley is claimed. What stands behind the offer is adjacent: Neometrix engineers a booster trolley (see the portable single cylinder nitrogen trolley with booster page), the ground and airborne oxygen system (see the aircraft oxygen system page) and a tyre nitrogen charging rig (see the aircraft tyre nitrogen charging rig page). The cylinders, valves, regulators, gauges, hose and couplings are catalogue items, bought in, not invented. What Neometrix engineers is the trolley around them: the circuit, the materials and their cleaning, the frame and the restraint, the hose stowage and the proof. So the honest position is that the trolley is engineered to order, the neighbouring disciplines are in the building, and the first trolley of this exact kind will be built around the customer's own gas, cylinders and system rather than taken off a shelf.

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

ISO 5145 covers the selection of cylinder valve outlet connections, and CGA G-4.1 covers cleaning equipment for oxygen service. This page prints none of their requirements, and no edition year: those come from the standard the customer names. The trolley charges from cylinders. It does not generate gas, it does not raise a gas above the cylinder pressure, it does not decide the charging pressure of the system it charges, and it does not replace the operator's own procedure. This page claims no certification or accreditation. No pressure, flow, size, capacity or quantity figure is printed here, and approval of a trolley 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 system rather than the trolley. First, the gas: nitrogen, air or oxygen, and whether it is for breathing. Second, the system: the pressure it accepts and the fitting on its charging port. Third, the cylinders: the type you use and how many the trolley should carry. Fourth, the handling: how far it is wheeled, over what ground, and where it is stored. Fifth, the cleanliness: the standard you require for oxygen, and how it is to be recorded. Sixth, the use: how often it is charged from, and by whom. From that we come back with a trolley concept, a circuit and test plan you can check, and a budgetary price.

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

Three neighbours: one boosts the gas, one is the whole oxygen system, one fills a tyre.

↗ The booster

Portable Single Cylinder Nitrogen Trolley with Booster

Raises nitrogen above the cylinder pressure - where this page charges a system from the cylinders as they are.

↗ The oxygen system

Aircraft Oxygen System

The whole ground and airborne oxygen system - of which a charging trolley is one working part.

↗ The tyre

Aircraft Tyre Nitrogen Charging Rig

Fills a tyre to a set pressure and stops - a different job from charging a system from a bank of cylinders.

Browse all Neometrix product lines.

Get a quotation

Tell us the gas,
and the system it has to charge.

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

Enquire — gas charging trolley Capability sheet (PDF) +91 7777 876 876

ISO 9001 / 14001 ENGINEERED-TO-ORDER CLASS — GAS CHARGING TROLLEY DUTY · CIRCUIT · MATERIALS · FRAME · BUILD · PROVE — RIGHT GAS, RIGHT PRESSURE. ENGINEERED IN NOIDA · INDIA