NMX‑GCU‑350 / Rev 00 / 90–350 bar · 0–4,500 m / Noida · India 2026 · Product Page

NMX-GCU-350 · ENGINEERED TO ORDER — MOBILE HP AIR COMPRESSION

Field air at 350 bar, pure enough to breathe.

Name: Mobile Gas Compression Unit (GCU)
Brand: Neometrix

A mobile gas compression unit — a towable four-wheel trolley carrying a three-stage compressor to 90–350 bar, a purification train to breathing-class purity (CO₂ ≤1 ppm, hydrocarbons ≤0.05 ppm), a high-pressure storage bank and protective filling boxes — rated for −20 °C and 4,500 m altitude, so cylinders are charged where the aircraft is, not where the plant is. Engineered to order — technically qualified in evaluation; the reference configuration on this page has not yet been built.

Enquire — compression units Capability sheet (PDF)

Illustrative image, not a delivered installation — a mobile gas compression unit: a four-wheel trolley with a braked towing bar carrying an enclosed high-pressure compressor unit under an openable canopy, with a control panel, tall purification cartridge housings and a small bank of storage cylinders, parked on a concrete apron

Fig · 01 The towable unit — compressor, purification and filling behind one towing bar — illustrative, not a delivered installation

Pressure

90–350bar

Delivery

300l/min class

Purity

≤1ppm CO₂

Altitude

4,500m rated

Ambient

−20/+55°C

ISO 9001 / 14001 Engineered to order Purity verified by gas analysis Acceptance testing in scope of supply Noida · India

Overview

At 350 bar, a trace becomes a dose.

Compressing air does not clean it — it concentrates everything in it. Inside a charged cylinder a contaminant sits at roughly 350 times its partial pressure — and whether moisture freezes, oil condenses or CO₂ accumulates is decided there, at pressure, not at the intake. That single fact shapes this machine: it is not a compressor with a filter on the end, it is a purity chain that happens to include a compressor.

Illustrative image, not a delivered installation — the purification train of a high-pressure compressor unit: a compact oil-and-water separator vessel and two tall slender purifying cartridge housings in polished stainless steel, plumbed in small-bore stainless tubing with a gauge and valves, mounted on a steel frame

Fig · 02 Separator and purifying cartridge housings — where the purity numbers are made — illustrative, not a delivered installation

The purity strategy runs in two stages, and the first one is economic. The high-pressure purifying cartridge is a consumable with a finite life — roughly 250 hours or 900 m³ of air. Intake CO₂ can reach 1,000 ppm. So a preliminary CO₂ desiccator cartridge cuts the intake concentration to a third before the high-pressure train ever sees it — the cheap cartridge protects the expensive one, and both are changed on a calendar, not on failure.

After three stages of compression, an oil-and-water separator takes out the condensate and the drying and purifying cartridges finish the job: particles to ≤5 µm, CO₂ to ≤1 ppm, hydrocarbons to ≤0.05 ppm, and moisture to a pressure dew point of ≤−20 °C — about −75 °C in atmospheric terms, roughly one part per million of water.

The trolley is not packaging. Braked towing bar, road-shock proof, −20 °C cold start, 4,500 m intake — the journey is part of the specification.

Engineered to Order

Qualified in evaluation, stated plainly

This configuration was engineered against an indigenous-development requirement for a mobile gas compression unit and passed technical evaluation; no order followed, so no delivered unit is claimed. Delivery rate, storage size and filling arrangement are settled at design review.

The Purity Chain

Desiccator → separator → cartridges

Preliminary CO₂ desiccator at the intake, oil-and-water separator after compression, drying and purifying cartridges to finish — sized for 0–1,000 l/min and 130–350 bar working, with every cartridge on a hard replacement calendar and purity proven by gas analysis at acceptance.

Built Around the Airfield

Charging happens behind protection

An approximately 200-litre storage bank of approved cylinders, two protective filling boxes referenced to NFPA practice so the cylinder being charged sits behind a barrier, a guarded outlet port, and a shelf for the spare bottles — on a trolley any airfield tractor can tow.

Architecture

One purity chain, on four wheels.

The schematic below follows the air from ambient intake to the charged cylinder — and the detail panel shows the trolley engineering that lets the whole chain arrive where it is needed.

FIG · 03UNIT ARCHITECTURE · INTAKE · DESICCATOR · 3-STAGE COMPRESSION · PURIFICATION · STORAGE · FILLING

Fig · 03 The purity chain from ambient air to a charged cylinder, with the protective filling boxes at the end — and the trolley that carries all of it

Arc · 01

Intake & Preliminary Desiccator

Ambient air — 15–100 % humidity, up to 1,000 ppm CO₂, possibly at 4,500 m — passes a cartridge-type preliminary CO₂ desiccator holding ~9 kg of absorbent, which cuts CO₂ to one third of the intake concentration. Its whole purpose is downstream economics: it protects the finite-life high-pressure cartridges from being spent on bulk CO₂.

Arc · 02

Three-Stage Compression

Atmospheric air to 90–350 bar in three stages with interstage cooling — because a single-stage machine attempting that ratio would cook its own valves and its lubricant into the very hydrocarbons the purity spec forbids. A 2.2 kW drive turns the block at ~900 rpm — ≤70 dB(A), on anti-vibration mounts, daily duty to 8 hours.

Arc · 03

Separator & Purifying Cartridges

A high-pressure oil-and-water separator drops the condensate, then drying and purifying cartridge assemblies (130–350 bar working, 420 bar max) finish to ≤5 µm, CO₂ ≤1 ppm, hydrocarbons ≤0.05 ppm and a pressure dew point ≤−20 °C — roughly 900 m³ of air per cartridge, changed on the calendar regardless.

Arc · 04

Storage, Filling Boxes & Protection

A ~200-litre bank of approved cylinders buffers the compressor, and charging happens in two protective filling boxes with their own gauges and valves. Above it all sits a layered pressure ladder: operating switch at 250/330 bar, safety switch at 340, final PSV at 350, sensor limit 350, valve ceiling 365 — mechanical protection outranking the controls.

Have a compression unit, cylinder charging or high-pressure air requirement? Send it across — clause-by-clause compliance matrix within two working days · [email protected]

Send tender spec

Specifications

Reference unit, sized to your duty.

The parameters below describe the reference towable unit. Delivery rate, storage volume, filling arrangement and trolley format are set by the cylinders being charged, the daily duty and the site.

Illustrative image, not a delivered installation — the filling side of a high-pressure compression unit: a steel filling box with its guard open showing a cylinder connection with gauge and valve, beside an operation panel carrying pressure gauges, a rotary selector and toggle switches, and a rack of vertical high-pressure storage cylinders strapped in place

Fig · 04 Filling box, operation panel and the storage bank — illustrative, not a delivered installation

Where field compressors actually fail

Rarely in the crankcase. They fail on the road — a gauge line fatigued by corrugations, a cartridge housing worked loose — and they fail quietly, by drifting out of purity while still making pressure. A machine can deliver a perfect 350 bar of air that no one should breathe.

That is why the acceptance regime here is the point, not the appendix: road-test cycles with functional verification afterwards, a cold test at −20 °C, gas-purity verification at a high-altitude station, and cartridges changed on a hard calendar rather than on complaint. The purity numbers are only claims until the analyser agrees.

Full specification — expand

System	Mobile gas compression unit — towable trolley carrying a three-stage high-pressure air compressor, two-stage purification chain, high-pressure storage bank, protective filling boxes and controls · design, engineering, fabrication, integration, testing, supply, documentation and training
Compression	Three-stage HP air compressor · operating 90–350 bar · delivery 85 or 300 l/min class · intake atmospheric · ~900 rpm · drive 2.2 kW, 230/440 V AC 50 Hz single/three phase, 24 V DC control · ≤70 dB(A) · unit ~255 kg · daily operating time to 8 h
Pressure Protection	Final pressure safety valve ≤365 bar · final pressure sensor ≤350 bar · operating pressure switch 250 / 330 bar · safety pressure switch OFF 340 bar · final PSV 350 bar · PRVs on the storage bank · NRV + isolation on the outlet port
Preliminary CO₂ Desiccator	Cartridge type, ~9 kg CO₂ absorbent · output CO₂ = 1/3 of intake (330 ppm from a 1,000 ppm maximum) · life ~250 h at 630 l/min FAD · changed at least every 12 months or 250 h even if not exhausted · 60 mm ID hose connections · ~50 × 46 × 72 cm, ~26 kg operating
Purification Train	HP oil & water separator (Ø95 × 306 mm, 0.54 L) + drying & purifying cartridge assemblies (Ø100 × 855 mm, 2.85 L) · flow 0–1,000 l/min · working 130–350 bar, 420 bar max · ~900 m³ regenerated per cartridge (200 bar, 30 °C reference)
Delivered Purity	Particles ≤5 µm · residual CO₂ ≤1 ppm · residual hydrocarbons ≤0.05 ppm · pressure dew point ≤−20 °C (≈−75 °C atmospheric class, ~1 ppm water) · breathing-class purity verified by gas analysis at acceptance
Storage & Filling	~200 L high-pressure bank (40/50 L × 5/4 cylinders, approved makes) · 2 × protective filling boxes with gauges and valves, referenced to NFPA practice · HP outlet port with isolation valve and NRV · four HP dial gauges · cylinder safety enclosure
Trolley	Fabricated four-wheel chassis ~2.6 × 1.32 × 1.85 m · carries the ~780 kg unit by road · towing bar with electrical connection for brakes, parking and turn indicators · ground clearance ≤500 mm · all-sides-openable canopy · spare-bottle shelf · on-board power socket and switch
Environment	−20 to +55 °C · altitude 0–4,500 m · inlet RH 15–100 % · thin, cold intake air treated as the design case for delivery, cooling and electrics
Acceptance Regime	Functional testing incl. gas-purity verification at a high-altitude station · road test 2 × 20 km with post-road functional verification · cold test at −20 °C · 100 % production acceptance testing with QA witness · O&M manuals with calibration details · operator training · ≥2-year warranty · spares supported for equipment life — all carried in the scope of supply
Sourcing	Compressor block, CO₂ desiccator, purification cartridges and approved storage cylinders are proprietary bought-in items from established makes · Neometrix fabricates the trolley, operation and connection panels, cylinder safety enclosure and 350 bar stainless piping, and carries integration, testing, documentation and training
Status	Engineered to order — reference configuration, not yet built · technically qualified in evaluation; no order followed · delivery, storage and filling arrangement settled at design review

PDF · 1 page

Mobile Gas Compression Unit — Capability Sheet

Tender Response

Send your specification — compliance matrix in two working days

Variants

Same discipline, different wheels.

Tenders call this a gas compression unit, a high-pressure air compressor, a charging set or a field compressor. What changes is the drive, the pressure class and what it stands on — the compression-and-purity discipline is common.

Var · 01

Towed GCU Trolley

The reference configuration — four-wheel trolley, braked and lit towing bar, canopy, 90–350 bar with full purification, storage and filling boxes. Towable by any airfield tractor at walking-to-convoy speeds.

Var · 02

Trailer-Mounted Diesel Screw Compressor

Engine-driven field air at scale for engineering and workshop duty where there is no grid at all — a diesel prime mover and rotary-screw stage on a road trailer. A class Indian army formations have tendered repeatedly.

Var · 03

Static Workshop Installation

The same compression and purification train mounted in a workshop or hangar bay, with larger storage and additional filling points — when the duty stays in one place, the trolley budget goes into bank capacity instead.

Var · 04

Nitrogen-Service Configuration

The same discipline applied to nitrogen — drawing from a PSA generator or cylinder supply rather than ambient air — alongside the wider Neometrix nitrogen charging and boosting line.

Applications

Where it applies.

Wherever high-pressure cylinders must be charged in the field, to a purity someone’s life may depend on.

A · 01Aircraft high-pressure air bottle charging at forward and high-altitude bases

A · 02Breathing-air set charging — rescue, fire and maintenance crews

A · 03Aircraft pneumatic & emergency-system servicing air

A · 04Naval & coast-guard cylinder charging afloat and ashore

A · 05Workshop & depot cylinder banks — static installations

A · 06Field engineering air — trailer-mounted diesel-driven compressors

FAQ

Common questions.

Plain-language answers from the engineering team.

Q · 01 Why does high-pressure air need this much purification?

Because compression concentrates whatever is in the air. What matters mechanically and physiologically is a contaminant’s partial pressure, which scales with total pressure: inside a 350 bar cylinder a trace sits at roughly 350 times the partial pressure it had at the intake, and wherever that air is then used at elevated pressure, the multiplication travels with it. Moisture is the mechanical version of the same problem — water that would stay vapour at ambient condenses at pressure, then freezes in a valve or regulator at altitude or in winter. So the purity targets are not refinement, they are the product: particles ≤5 µm, CO₂ ≤1 ppm, hydrocarbons ≤0.05 ppm, and a pressure dew point of −20 °C or better, which at working pressure corresponds to roughly one part per million of water.

Q · 02 Why is there a CO₂ desiccator before the compressor train?

Economics, stated honestly. The high-pressure purifying cartridge is the expensive consumable, and its life is finite — on the order of 250 running hours or about 900 m³ of air. If it had to absorb the full intake CO₂ load, which can reach 1,000 ppm near vehicles and generators, it would exhaust far faster. The preliminary desiccator is a larger, cheaper cartridge of about 9 kg of absorbent that cuts CO₂ to one third of the intake concentration before compression. The cheap cartridge takes the bulk load so the expensive one only polishes. Both are changed on a fixed calendar — at least every 12 months or 250 hours, whichever comes first, even if not exhausted — because a purity consumable past its date is a fault you cannot see.

Q · 03 What does “pressure dew point ≤−20 °C” actually mean?

The dew point is the temperature at which moisture in the air starts to condense — and it depends on pressure. Compressing air crowds the same water molecules into a smaller volume, so air that seemed dry at ambient can rain inside a vessel at 350 bar. Quoting the dew point at working pressure — the pressure dew point — is therefore the honest number. A pressure dew point of −20 °C means that even at full pressure, nothing condenses until the air is chilled below −20 °C; expanded back to atmosphere, the same air has a dew point around −75 °C, roughly one part per million of water. That margin is what keeps regulators and valves from icing when a cylinder is used in winter or discharged quickly, which is itself a refrigeration event.

Q · 04 Why three compression stages instead of one?

Because a 1-to-350 pressure ratio in a single stroke is thermodynamically brutal. Compression heats the gas, and the temperature rise grows with the ratio per stage; one stage attempting the full ratio would run hot enough to degrade its lubricant — manufacturing exactly the hydrocarbon contamination the purity spec forbids — and hot valves and seals fail early. Splitting the work into three stages with cooling between them keeps each stage at a civilised ratio, keeps discharge temperatures within what the oil tolerates, improves efficiency, and lets the interstage coolers drop out condensate progressively rather than all at once at the end. The purity chain genuinely starts inside the compressor, in the choice to compress gently three times rather than violently once.

Q · 05 Why does the altitude rating matter for a compressor?

Because a compressor’s intake is its raw material, and at altitude there is simply less of it. At 4,500 m the ambient pressure is roughly 40 % lower than at sea level, so each intake stroke swallows proportionately less air mass — delivery falls, the machine runs longer for the same charge, and air-cooled heat exchange also works with thinner air. Electrical machines and switchgear derate at altitude too. A unit rated 0–4,500 m with −20 °C cold start has had its delivery, cooling and electrics sized for the thin, cold end of that envelope rather than the datasheet-friendly end — and the acceptance regime proves it where it counts, with functional testing and gas-purity verification carried out at a high-altitude station, not just in the factory.

Q · 06 Do you make the compressor block?

No — and the tender this configuration was engineered against says so too, specifying the block by reference and expressly allowing any suitable make. High-pressure compressor blocks, CO₂ desiccators, purifying cartridges and certified storage cylinders are proprietary items from established manufacturers, and pretending otherwise would be theatre. What Neometrix engineers and builds is the unit: the fabricated four-wheel trolley and its braked, lit towing bar, the operation and connection panels, the cylinder safety enclosure, the 350 bar stainless piping, and the integration of the whole purity chain — followed by the part that makes it real, the road tests, the cold test, the altitude purity verification and the documentation and training. That is the same division of work as our gas cascade and refuelling systems: the pressure parts are bought certified; the machine around them is ours.

↗

High-pressure air & gas from Neometrix.

Compression, boosting, distribution and test systems engineered at our Noida facility.

↗ Ground Support

Nitrogen Cart with Booster

Mobile nitrogen charging for aircraft servicing.

↗ HP Air

Pressure Reducing Panel (PRP) — HP Air

Regulated let-down from high-pressure air storage.

↗ Test Systems

High-Pressure Air Compressor Test Stand

We build the units — and the stands that prove them.

Browse all Neometrix product lines.

Get a quotation

Send your cylinders
and your duty cycle.

The Defence Programmes desk replies within two working days with a clause-by-clause compliance matrix and a budgetary quotation. Write to [email protected] or use the form.

Enquire — compression units Capability sheet (PDF) +91 7777 876 876

ISO 9001 / 14001 ENGINEERED TO ORDER — MOBILE HP AIR COMPRESSION ACCEPTANCE REGIME · PURITY BY GAS ANALYSIS ENGINEERED IN NOIDA · INDIA

Field air at 350 bar, pure enough to breathe.

At 350 bar, a trace becomes a dose.

Qualified in evaluation, stated plainly

Desiccator → separator → cartridges

Charging happens behind protection

One purity chain, on four wheels.

Intake & Preliminary Desiccator

Three-Stage Compression

Separator & Purifying Cartridges

Storage, Filling Boxes & Protection

Reference unit, sized to your duty.

Where field compressors actually fail

Same discipline, different wheels.

Towed GCU Trolley

Trailer-Mounted Diesel Screw Compressor

Static Workshop Installation

Nitrogen-Service Configuration

Where it applies.

Common questions.

High-pressure air & gas from Neometrix.

Nitrogen Cart with Booster

Pressure Reducing Panel (PRP) — HP Air

High-Pressure Air Compressor Test Stand

Send your cylinders
and your duty cycle.

Similar Products

Share This Page

Field air at 350 bar, pure enough to breathe.

At 350 bar, a trace becomes a dose.

Qualified in evaluation, stated plainly

Desiccator → separator → cartridges

Charging happens behind protection

One purity chain, on four wheels.

Intake & Preliminary Desiccator

Three-Stage Compression

Separator & Purifying Cartridges

Storage, Filling Boxes & Protection

Reference unit, sized to your duty.

Where field compressors actually fail

Same discipline, different wheels.

Towed GCU Trolley

Trailer-Mounted Diesel Screw Compressor

Static Workshop Installation

Nitrogen-Service Configuration

Where it applies.

Common questions.

High-pressure air & gas from Neometrix.

Nitrogen Cart with Booster

Pressure Reducing Panel (PRP) — HP Air

High-Pressure Air Compressor Test Stand

Send your cylindersand your duty cycle.

Similar Products

Share This Page

Send your cylinders
and your duty cycle.