Application Guide · Medical Oxygen · GOST 6331 · Cylinder Filling · Russia / CIS
Medical oxygen for clinical use in Russia is governed by GOST 6331 — a standard that specifies purity, moisture content, and the prohibition of hydrocarbon contamination in the gas delivered to patients. The oxygen compressor filling medical cylinders is a critical point in the purity chain from the oxygen source to the patient. This guide covers the GOST 6331 requirements, and the oil-free design specification, and the ZW, DW, and LW series configurations available for medical cylinder filling service in Russia and the CIS.
✓ Oil-Free PTFE Cylinders
✓ GOST 12.2.052 Safety
✓ ZW / DW / LW · Russia
ZW series oil-free oxygen compressor for medical cylinder filling — PTFE self-lubricating piston rings, copper-free wetted components, labyrinth distance piece, discharge to 15 MPa (GOST 949). Compliance requires zero hydrocarbon contamination in the oxygen delivered to medical cylinders; the oil-free compressor design is the only specification that meets this requirement.
GOST 6331: Medical Oxygen Requirements in Russia
GOST 6331 is the Russian national standard governing the purity and quality of oxygen supplied in cylinders for inhalation therapy, anaesthesia, and other clinical applications. It establishes minimum purity of 99.5% O₂ by volume (Grade 1) or 99.2% for Grade 2, with strict limits on moisture content, carbon dioxide, carbon monoxide, and hydrocarbon contamination. The standard applies to the final oxygen product delivered to the patient-facing cylinder, meaning every step in the gas handling chain — from the air separation unit or oxygen generator to the cylinder filling compressor to the filled cylinder — must preserve or improve the purity established at the source.
The specific limits under this standard that are most directly relevant to the oxygen compressor specification are the oil and hydrocarbon prohibitions. Grade 1 prohibits any detectable oil or hydrocarbon contamination in the medical oxygen product. At the cylinder filling compressor, this means the oxygen passing through the compression system must not pick up any hydrocarbon lubricant from the cylinder walls or from oil mist migrating from the crankcase. A conventional lubricated-cylinder compressor — even one with a high-efficiency oil separator and downstream activated carbon filter — cannot meet the «not detectable» oil limit with certainty across its full service life. The oil-free cylinder design is the only specification that eliminates hydrocarbon contamination at the source, making it the standard for all cylinder filling compressors for medical service in Russia and CIS.
| Parameter | Grade 1 (GOST 6331) | Grade 2 | Compressor Impact |
|---|---|---|---|
| O₂ purity (vol %) | ≥ 99.5% | ≥ 99.2% | Oil-free cylinder prevents hydrocarbon dilution of purity |
| Oil and hydrocarbons | Not detectable | Not detectable | Oil-free design mandatory; no filter substitute permitted |
| Moisture (H₂O) | ≤ 0.009 g/m³ | ≤ 0.009 g/m³ | Inter-stage coolers and aftercooler moisture knock-out required |
| CO₂ content | ≤ 0.05% | ≤ 0.05% | Controlled by source; compressor does not add CO₂ |
| CO content | ≤ 0.0005% | ≤ 0.0005% | Oil-free design prevents CO formation from incomplete hydrocarbon combustion |
GOST 6331 limits shown for the primary parameters relevant to oxygen compressor specification. Full standard covers additional parameters. Russian medical oxygen must be certified against GOST 6331 by an accredited laboratory before release for clinical use.
The Medical Oxygen Compressor Specification
The oil-free compressor for medical cylinder filling combines the safety requirements of GOST 12.2.052 — which governs oxygen equipment safety and prohibits hydrocarbon lubricants above 0.5 MPa — with the product purity requirements of GOST 6331. These two standards together define the minimum specification for any medical oxygen compressor in Russia: oil-free PTFE or PEEK piston rings, double-compartment labyrinth distance piece, copper-free wetted components, and oxygen-degreased assembly at the factory. There is no regulatory pathway for a lubricated-cylinder oxygen compressor in medical service in Russia regardless of downstream filtration, because GOST 6331 does not accept a detection limit for oil contamination — it requires non-detectable, which only the oil-free design can guarantee throughout the compressor service life.
Beyond the mandatory oil-free specification, machines for GOST 6331 medical service carry additional design requirements compared to industrial oxygen compressors handling the same gas:
Regulatory Requirement
In Russia, the use of a lubricated-cylinder oxygen compressor for medical cylinder filling is not a decision that can be made on technical grounds alone. A medical oxygen cylinder filled by a lubricated compressor — even one with downstream oil filtration — does not comply with GOST 6331 and cannot be legally released for clinical use. Operating such a compressor risks withdrawal of its medical gas production licence under Federal Law 61-FZ «On the Circulation of Medicines.» The oil-free compressor specification is a regulatory prerequisite, not a quality preference.
ZW, DW, and LW Series for Medical Oxygen Cylinder Filling
The ZW, DW, and LW series oxygen compressors are all available with the oil-free PTFE cylinder configuration for medical cylinder filling service. The series selection follows the same capacity and frame-type criteria as for industrial oxygen compression, with the additional specification requirements for medical service applied across all series:
| Station Type | Flow (m³/h O₂) | Discharge Pressure | Recommended Series | Power (kW) |
|---|---|---|---|---|
| Small clinic / hospital | 1–5 | 15.0 MPa | ZW series, 3-stage | 11–30 |
| Regional filling station | 5–30 | 15.0 MPa | ZW or DW, 3-stage | 30–110 |
| Large medical gas distributor | 30–100 | 15.0 MPa | DW or LW, 3-stage | 110–300 |
| Industrial medical O₂ centre | 60–200+ | 15.0 MPa | LW series, 3-stage | 200–500+ |
All configurations oil-free PTFE cylinder specification, GOST 12.2.052 and GOST 6331 compliant, 3-stage compression from atmospheric suction to 15 MPa (GOST 949). LW series opposed-balance frame for permanent rigidly-piped installations above 30 m³/h; ZW series for small stations with flexible hose filling connections.
The Medical Oxygen Supply Chain in Russia
Russian medical oxygen reaches the patient through a regulated supply chain that involves several stages, each governed by specific standards and licensing requirements. Understanding this chain helps clarify where the oxygen compressor fits and what its role is in maintaining GOST 6331 compliance.
Food-Contact Blow Air Purity in ISBM Production — Parallels with Medical Oxygen Standards
The GOST 6331 «not detectable» oil limit has a direct analogue in the food-contact compressed air standards applied to blow air in injection stretch blow moulding (ISBM) production of beverage and food packaging. ISO 8573-1 Class 1 oil content (below 0.01 mg/m³ aerosol) and TR TS 021/2011 (the Eurasian food safety technical regulation) together establish that blow air contacting the interior of a PET bottle during the stretch-blow cycle must be essentially hydrocarbon-free. As with GOST 6331 medical oxygen, downstream oil filtration alone is not sufficient — it must be verified continuously and maintained throughout the equipment service life. The cleanest engineering solution in both cases is the same: specify an oil-free compression stage, eliminating the contamination source rather than relying on downstream removal.
FAQ — Medical Oxygen Compressor in Russia
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Oil-free ZW, DW, and LW series compressors for GOST 6331 medical cylinder filling — PTFE piston rings, copper-free components, GOST 12.2.052 and GOST 6331 documentation package. Full licensing support documentation in Russian. Response within 48 hours.