Medical Air Systems for Healthcare Facilities

Medical air systems are a vital element of all hospitals and most other healthcare facilities


The engineer must consider expense, capacity, physical size and weight, space limitations, and mechanical and electrical utility availability in choosing a system for a particular project. It is important to coordinate the equipment selections with the owner as well as other engineering and architectural disciplines.

The first priority is life safety. Medical air is used for respiratory therapy and calibration of medical devices for respiratory application. Providing clean, oil-free air is mandatory. The medical air system should not be used to supply air for any other purpose (e.g., hospital laboratory use) because of the opportunities for contamination of the distribution system. If a patient inhales medical air contaminated by oil from a defunct compressor or nitrogen from a brazing purge, the consequences could be irreversible. In addition, a utility or pipeline shutdown must be coordinated with the hospital staff to prevent an termination while patients are connected to the system. Engineers should be aware of the requirements before designing any medical gas system.

Distribution Systems

Medical compressed air systems must be designed to prevent the introduction of contaminants or liquid into the pipeline. Medical air systems must:

  • be supplied from cylinders, bulk containers, or medical air compressor sources; or reconstituted from oxygen USP and oil-free, dry nitrogen
  • meet requirements of the medical air
  • contain no detectable liquid hydrocarbons
  • contain fewer than 25 ppm gaseous hydrocarbons
  • contain 5 mg/m3 or less of permanent particulates sized 1 micron or larger at normal atmospheric pressure.

In a typical fully functioning healthcare facility, the medical air is supplied by a high-pressure cylinder manifold system or a medical air compressor system. Manifold distribution systems typically are used in facilities that have very little demand for medical air. Medical air compressor plants typically are for larger facilities.

Existing facilities may choose to upgrade their equipment and associated pipeline or add medical air plants as the facility expands. When selecting a piece of equipment for a new facility, the possibility of future expansion should be considered. To allow for future growth, it is good practice to be conservative in sizing a system.

Duplex Medical Air Compressor Source Systems

An engineer usually has more options available when designing for a new facility than for a renovation or replacement project. Electrical and mechanical utilities can be more easily calculated, and chilled water, ventilation, and electrical services can be sized and adequately located. The ideal schematic design contains a well-ventilated, easily accessible mechanical room dedicated to medical gas equipment.

In selecting a medical air compressor for an upgrade, the engineer may have some trouble due to mechanical utility inefficiencies (e.g., poor chilled water quality, a poorly ventilated mechanical space). The local electric utility may not support the pump arrangement, or poor equipment access may require breakdown of equipment parts at a significant cost increase. It is imperative to conduct thorough surveys of the surrounding mechanical space and utilities before determining the best type of compressor for the project.

It is a good idea to select more than one type of compressor at the schematic design phase. You should develop a master plan that shows existing demand and estimated spare capacity. The owner may want to obtain a cost estimate before making a final decision.

Types of Compressors

All medical air compressors must be able to deliver compressed air that does not contain oil. This article specifically deals with medical air systems for Level 1 hospitals.

There are three acceptable types: These reciprocating compressors have no oil film on surfaces exposed to air being compressed. They do have oil in the machine and require separation of the oil-containing section from the compression chamber by at least two seals. The interconnecting shaft and seals must be visible without disassembling the compressor.