Medical Vacuum Pump Systems for Hospitals: Rotary Vane, Claw and Liquid-Ring Compared

What a medical vacuum plant consists of

A vacuum plant normally has at least two pumps in duty and standby, a vacuum receiver (vessel) that stabilises the level, a bacterial filter on the inlet side to protect the pumps, and an exhaust line taking filtered discharge to a safe location outside the building. A control panel starts and rotates the pumps and raises alarms.

The pipework collects from terminal units at the bedside. The overall design logic is in medical vacuum system design, and the general system appears in what a medical vacuum system is.

Rotary vane pumps

Rotary vane pumps use vanes sliding in a slotted rotor inside an off-centre housing. They are the most common choice in hospitals, available in oil-lubricated and dry (oil-free) forms. Oil-lubricated pumps reach deep vacuum efficiently but need oil changes and an oil mist separator on the exhaust. Dry vane pumps avoid oil but have carbon vanes that wear and must be replaced on schedule.

They are compact, relatively quiet and economical in purchase cost, which suits small and medium plants. Their main service items are vanes, oil, oil filters and exhaust separators, so confirm that spares are held locally and that the supplier can describe the expected interval for each item at your duty cycle.

Claw pumps

Claw pumps use two counter-rotating claw-shaped rotors that do not touch each other or the housing, so compression takes place without lubricant or wearing contact. This gives long service intervals and clean exhaust. They offer good energy efficiency, particularly with variable-speed drives, and are increasingly used in new installations.

Their purchase price is generally higher, and noise and heat require a good plant room. The same working principle is described for compressors in medical air compressor types.

Liquid-ring pumps

Liquid-ring pumps use water in a ring around an impeller to create the seal and compression. They tolerate moisture and contamination well and are robust, but they consume water, require water treatment and discharge and are less energy-efficient than other types. In modern medical plants they are less common than vane or claw pumps. If a design calls for one, ask how water supply, drainage and temperature will be handled in the plant room, because those utilities become part of the risk assessment.

Infection control and exhaust

Whatever the pump, the plant must filter exhaust to protect people from contaminated air. MZ Liberec's MIL's vacuum stations include an antibacterial filter and a secretion trap, maintain suction and flow automatically and cover capacities from 6.4 to 632 Nm³/h. See the MIL's vacuum stations.

Exhaust should discharge away from air intakes, windows and walkways, and filters should be replaced and disposed of according to the maintenance plan, described in vacuum system maintenance.

Comparison criteria

UAE requirements for devices and facilities are set by authorities such as MOHAP, DHA and DOH, so confirm the current rules. To discuss pump selection for a new plant, contact Beckfinity.

• Ultimate vacuum level and capacity at the specified operating pressure.
• Oil-free or oil-lubricated design and its impact on exhaust and servicing.
• Energy use at part load and availability of variable-speed control.
• Noise, heat output and plant-room needs.
• Wearing parts and service interval, with local engineer support.
• Redundancy: at least two pumps, each able to carry the peak demand according to the design.