How often should medical gas outlets be tested?

What the quarterly test covers

• A blank probe is inserted to test gas-specificity, mechanical function and leaks. The probe should not swivel in a wall outlet but must rotate freely in a pendant or boom outlet.
• Flow and pressure drop are tested with a test instrument against the pressures HTM 02-01 sets at defined outlet flows.
• Blank probes are used only for leak tests; flow and pressure-drop tests need a calibrated flowmeter, pressure gauge and calibrated jet, and test equipment is calibrated against national standards at least once a year.
• Probes, particularly on high-pressure hoses, can be ejected from the outlet with considerable force, so they are restrained during removal.

Scheduling and records

All outlets should be serviced at each visit, with extra visits for outlets that were in use and could not be tested. Results are recorded for each outlet, including static and flow pressures, issues found and repairs. Hose assemblies in medical supply units such as pendants are given a service life of five years, because their condition cannot be judged by looking at them.

Other tests that involve outlets

• After repairs and modifications: tests relevant to the work are done before the system is taken back into use, with quality control testing where the supply was interrupted.
• Low-usage areas: HTM 02-01 recommends ad hoc quality control testing in low-usage or dormant areas, and testing before an empty ward is reopened for patients.
• On-site sources: gas from PSA plants and medical air compressors is tested at least quarterly.

Outside England, WHO notes that the system needs maintenance, cleaning and testing according to relevant national and international standards.