That the component has been processed to remove hydrocarbons and particulate to a defined standard, and packaged to stay that way until installation.

Ordinary manufacturing leaves cutting oils, drawing compounds, greases and handling residues on and inside components. In air service that is harmless. In oxygen service it is fuel sitting in an oxidiser at pressure.

Oxygen cleaning is a controlled process - degreasing with appropriate solvents, rinsing, drying, and verification against a specified maximum residual hydrocarbon level - followed by sealing the component in packaging that keeps contamination out until it is fitted.

The verification and the packaging are both part of it. A component that has been cleaned and then left open on a bench is no longer clean.

When ordering, specify oxygen service explicitly and expect documentation. Components supplied as standard air equipment are not suitable, even where they are physically identical in every other respect.

Because oil and grease can ignite in pressurised oxygen with no external ignition source at all, and the resulting fire can consume the metal around it.

In ordinary air, oil needs a substantial ignition source. In an oxygen-rich stream at pressure, the combination of high oxygen concentration and the heat of compression - for example when a valve is opened rapidly and gas compresses adiabatically downstream - can raise a film of oil to its ignition temperature spontaneously.

Once a hydrocarbon fire starts in an oxygen system, it burns intensely enough to ignite the pipe or valve body itself. Metals that are entirely non-combustible in air will burn in oxygen once initiated.

This is why the prohibition on hydrocarbons is absolute rather than a matter of degree, why oxygen valves are opened slowly, and why only oxygen-compatible lubricants may be used - and only where the manufacturer specifies them.

Materials chosen for compatibility at the intended pressure, with the selection getting stricter as pressure rises.

Metals commonly used include certain stainless steels, copper and copper alloys such as brass and bronze, and Monel for the most demanding duty. Their suitability depends on pressure and on whether the geometry could produce a high-velocity impingement.

Non-metallics are more restrictive because most polymers and elastomers burn readily in oxygen. PTFE and certain fluoropolymers are the usual choices for seals and seats, selected specifically for oxygen compatibility.

Lubricants, where required at all, must be oxygen-compatible types - typically fully fluorinated products - and used sparingly and only where specified. General-purpose greases, PTFE tape not intended for oxygen service, and standard thread sealants are all unacceptable.

Material selection should follow the recognised guidance for oxygen systems at the working pressure rather than being decided component by component.

Functionally yes - it reconciles steady production with variable demand - but it is an oxygen-service vessel and must be specified as one.

The sizing logic is identical: the generator produces at a fixed rate, the process draws in peaks, and without storage the peaks pull gas through the beds too fast and purity falls. The receiver is sized from the peak flow, its duration and the acceptable pressure band.

What differs is the vessel itself and everything connected to it. It must be manufactured, cleaned and certified for oxygen service, with oxygen-compatible internal coatings if any, and its valves, gauges and drain arrangements likewise.

Drain arrangements deserve thought, since any liquid collecting in an oxygen receiver is a contamination question rather than a nuisance.

The inlet-side receiver, which sits in the compressed air system before the generator, is ordinary air equipment - the oxygen service boundary begins at the generator outlet.

Product purity, and atmospheric oxygen concentration in the plant room - the second being a safety requirement rather than a process one.

A purity analyser on the product line confirms the generator is performing and gives early warning of sieve degradation, valve leakage or a drying failure. Trend it rather than spot-reading it.

Atmospheric monitoring inside the enclosure or plant room detects oxygen enrichment from leaks. This matters because enrichment is undetectable by any human sense while making clothing, hair, and ordinary materials dramatically more flammable - a spark that would be harmless in air can start a serious fire in an enriched atmosphere.

Enrichment monitors with alarms, adequate designed ventilation, and clear signage restricting ignition sources are standard practice in oxygen generator rooms.

Include the monitoring in the maintenance schedule. A sensor that has drifted or expired is providing false reassurance, which is worse than no monitor at all.

Only if they are also made from oxygen-compatible materials, and the cleaning is done to a verified standard - so in practice, buy components specified for oxygen service.

Cleaning addresses contamination. It does nothing about the materials the component is built from, and material compatibility is the other half of the requirement. Many standard valves and fittings use elastomers, plastics or lubricated internals that burn readily in oxygen regardless of how clean they are.

Even where the materials happen to be suitable, cleaning to oxygen standard is a controlled process with verification, not a wash in solvent. A component cleaned informally has no evidence behind it.

There is also the question of what happens next: a correctly cleaned part contaminated during installation by ordinary thread sealant or an oily glove is back where it started, invisibly.

Specify oxygen service at purchase, keep the documentation, and control the installation practice as carefully as the procurement.

Material and cleanliness control at every intervention, not just at installation - because maintenance is where oxygen systems are most often compromised.

The procedure should name the permitted lubricants explicitly and prohibit everything else, specify oxygen-service replacement parts by part number rather than by description, and require that components are kept sealed until fitted.

It should require clean tools and clean hands, and prohibit general-purpose thread sealants and tapes not intended for oxygen service.

It should also cover the monitoring: analyser calibration, enrichment monitor testing and sensor replacement at their stated intervals, because an expired sensor gives false reassurance.

And it should require re-verification after any work that opened the system.

The reason to write all of this down is that a fitter working correctly on an air system will do several things that are unacceptable here, and none of them will look wrong at the time.