Where should a medical vacuum plant exhaust?

The exhaust is the last stage of the plant. On the way to the pumps, the air passes a duplex set of bacteria filters with drainage traps (HTM 02-01, 2026); the Portuguese ACSS specification places this double treatment upstream of the vessels so that the exhaust is free of bacteria and liquids. The discharge point still needs care, for reasons of air quality, noise and plant performance.

What HTM 02-01 (2026) asks for

• Terminate the exhaust clear of windows, ventilation intakes and the intakes of air compressors and other equipment.
• Turn the pipe downwards against rain and fit a mesh guard against insects, vermin and birds.
• Fix weatherproof notices at the discharge point identifying it as a medical vacuum discharge point that must not be obstructed.
• Fit a drainage valve and a transparent collection jar at the lowest point of the exhaust pipe.
• Size the exhaust so that its back pressure at system design flow matches the pump performance, and keep the outlet away from solid surfaces that could obstruct it.
• Assess exhaust noise and fit a silencer where noise could be a problem.
• Do not use common discharge pipes, to avoid backflow or a venturi effect; the HTM plant diagram shows an individual exhaust with an insect screen.

Why the location matters

Air quality: the same guidance asks for medical air compressor intakes to be placed to minimise contamination from vacuum system and AGSS discharges, and it expects oil fumes in the exhaust of oil-lubricated pumps. Performance: the pumps should be able to reach a higher vacuum than the pipeline needs to overcome bacteria filter resistance and exhaust back pressure, which is why the exhaust has to be sized for the pump. Infection control: central vacuum should not be connected to an infectious diseases unit, and where a dedicated local plant serves one, its exhaust location has specific infection risks to consider in design.

In Portugal, ACSS ET 03/2006 (v.2024) asks for the vacuum exhaust to go to a remote point outdoors, away from air intakes.

ULTRAVAC plants are supplied with one, two or more exhaust pipes, two bacterial filters with liquid separator, and a translucent trap that collects condensate from the exhaust.