Medical Gas Outlet Testing and Commissioning: What Must Be Verified Before Handover

Why verification is mandatory in practice

A medical gas pipeline is a life-support service. Errors such as a crossed pipe between oxygen and air, an unbrazed joint or a blocked line cannot be seen by looking at the wall. Recognised standards, including HTM 02-01 and ISO 7396-1, therefore require documented tests after installation and before use, usually witnessed by an independent authorised person or consultant.

Local authorities such as MOHAP, DHA and DOH may add their own requirements, so confirm the current rules for your emirate before planning the test programme.

Tests before the system is connected to the source

These tests are carried out section by section, preferably before walls are closed so that faults can be repaired without demolition. Details of installation practice are in medical gas pipeline installation.

• Pipework cleanliness and bore checks, including that pipes were degreased and capped before installation.
• Strength and leak tests: the installed system is pressurised with oil-free air or nitrogen at a defined pressure and monitored for pressure drop over a defined period.
• Blow-through to clear particles from the pipe, checking at terminal units for contamination.
• Cross-connection test: each gas is pressurised in turn while all others are verified at zero, proving the circuits are separate.

Outlet tests: flow, mechanical function and identity

Each terminal unit is tested for mechanical function: the probe should insert, lock, release and the shut-off should operate smoothly. Flow and pressure drop are checked at the outlet at the specified flow, for example when several outlets in a zone draw gas at once, to demonstrate that the pipework delivers enough under diversity.

Gas identity is confirmed at every outlet with an analyser, so that the gas present is the gas labelled. Colour and labelling are also reviewed; see the medical gas colour code. Connector standards should match the equipment, as in outlet connection standards.

Alarms, valves and source changeover

Alarm testing proves that each low- and high-pressure condition actually triggers the correct signal at every panel. A unit such as the MZ Liberec MZU II is configured on site through its touchscreen, with thresholds for the monitored gases that should be set, then simulated and recorded. It monitors pressure and flow for one to twelve gases and gives light and acoustic alarms.

Zone valves should be operated to confirm that they isolate the correct area and that the downstream alarm responds. Source changeover from duty to reserve supply is tested by simulating a failure, and the plant's own alarms are verified.

Purity and certification

Medical oxygen and air are sampled and analysed for gas identity, concentration and typical contaminants such as water vapour, oil and particles, with limits based on the pharmacopoeia or standard named in the contract. For medical air from a compressor plant, the analysis includes dew point and oil content.

The complete record, with test certificates, drawings and calibration records of instruments, is the basis for the medical gas certification and verification statement issued at handover. More on the air tests is in medical air quality testing.

A handover checklist

Request this list in the tender so that the commissioning scope is priced. If you want a test plan reviewed for a new building, contact Beckfinity and our specialists will help.

• As-built drawings and a zone and valve schedule.
• Pressure, leak, cross-connection and flow test reports.
• Purity and identity analysis certificates.
• Alarm and changeover test sheets.
• Operating and maintenance manuals, spare list and training record.
• Labels and legends installed and checked.