In brief
A vacuum pump draws gases or vapours out of an enclosed space and creates a pressure there below atmospheric pressure.
Contents
What is Vacuum pump?
In industry, vacuum pumps are used for clamping, lifting and gripping, vacuum packaging, drying and degassing, plastics processing, paper machines and laboratories. Depending on the achievable pressure, a distinction is made between rough, fine and high vacuum; for higher vacuum levels, several pumps are often combined.
Common designs are rotary vane pumps in oil-lubricated or dry-running versions, liquid ring pumps for humid or vapour-laden gases, claw and screw vacuum pumps for oil-free operation, and Roots pumps to increase pumping speed. For high vacuum, turbomolecular and other special pumps are added. Key ratings are pumping speed, achievable ultimate pressure, drive power, tolerance of vapours and particles, and type of lubrication.
Depending on the design, wear affects vanes, bearings, shaft seals, separator elements and filters. Oil-lubricated pumps require regular oil changes; vapours or particles drawn in shorten service life considerably. In processes that come to a standstill without vacuum, such as packaging or drying, vacuum pumps are considered critical spare parts. A standby pump or a stocked service kit shortens downtime considerably. Before replacement, it should be clarified whether the extracted medium contains vapours, particles or aggressive components.
In practice: maintenance and procurement
For replacement and maintenance, the design, pumping speed, ultimate pressure, motor data, oil type and designations of inlet and exhaust filters are needed. Oil separator and filter elements as well as vanes should be stocked as maintenance material.
Synonyms and abbreviations: rotary vane pump · liquid ring pump · vacuum generator · vacuum compressor
Frequently asked questions
What types of vacuum pumps are there?
For rough and fine vacuum, rotary vane, liquid ring, claw, screw, diaphragm and Roots pumps are common. For high vacuum, turbomolecular and other special pumps are usually combined with a backing pump. The choice depends on the required pressure, the pumping speed and whether the extracted gas contains moisture, vapours or particles.
What is the difference between an oil-lubricated and a dry-running vacuum pump?
Oil-lubricated pumps use oil for sealing, lubrication and cooling and achieve a low ultimate pressure, but require oil changes and separators. Dry-running pumps work without oil in the pumping chamber, avoid oil mist and contamination and need less maintenance, but depending on the design reach different pressure ranges. Oil-free pumps are often chosen for food and cleanroom applications.
What information is needed to replace a vacuum pump?
The design, pumping speed in cubic metres per hour, achievable ultimate pressure, motor power, voltage and frequency, connection sizes and the type of extracted medium with its moisture and vapour content are needed. The nameplate and serial number help to identify the right model or spare parts such as vanes, filters and seals unambiguously.
Why does a vacuum pump no longer reach its ultimate pressure?
Possible causes are leaks in pipes and connections, clogged inlet filters, worn vanes or seals, contaminated or insufficient oil and vapours drawn in that condense in the oil. A test with the inlet port shut off shows whether the pump itself or the system is the cause.