How often are PSA and medical air plant filters changed?

HTM 02-01 Part B (2026) says filters on a medical gas pipeline system should be changed at the intervals recommended by the manufacturer, and that this frequency should be increased if a filter becomes wet or its pressure drop exceeds the supplier's specification. Part A adds that a differential pressure gauge signals critical failure rather than servicing requirements, so it does not remove the need for regular inspections.

Which filters are involved

In a medical air plant, HTM 02-01 places an air-inlet filter immediately upstream of each compressor and, in the dryer system, typically a water filter/separator, an oil filter, two desiccant columns, a dust filter, a carbon filter and a bacteria filter. For a PSA oxygen plant it asks for duplexed filters and duplexed molecular sieves, with all duplexed components capable of independent operation.

Inspection routines in published procedures

The USAID RISE standard operating procedure for PSA plants (March 2022), written for hospitals in India, has operators inspect the pre-filter daily, inspect the carbon, fine and bacterial filters monthly, and replace filter elements as part of the annual inspection. It also says filters should be replaced on time as per the manufacturer's recommendation, and that operators may contact the manufacturer or supplier if the operation and maintenance manual is not clear.

For compressor inlet filters, the Compressed Air Challenge maintenance fact sheet for industrial compressed air systems (May 2026 revision) says cartridges are inspected and cleaned or replaced per manufacturer specifications, that the required frequency is often related to operating conditions, and that dirty filters increase energy consumption and can reduce compressor capacity and efficiency.

Changing filters without stopping supply

Under the HTM 02-01 permit-to-work arrangements, changing oil, filters or desiccant on plant can be work with no interruption to supplies; in such cases a Designated Clinical Officer (MGPS) signature may not be required, although QC testing may be required using a low-hazard permit to work.

Ultra Controlo plants

The 2022 ULTRAOX datasheet lists a compressed air treatment package with a water separator with electronic drain and high-efficiency micro, sub-micro and activated carbon filters, and a high-efficiency particulate filter for the medical oxygen. The ULTRADRY adsorption dryer has a coalescing filter at the inlet and a dust filter at the outlet, and its desiccant is held in replaceable cartridges.