Liquid ring vacuum pumps are used for operating vacuum level up to 33-44 mbar a, depending on liquid ring temperature. Moreover, it is fairly cheap. They provide a high reliability because of their simplicity.
This type of pumps are normally used to handle gas mixtures which contain condensable vapours.
When the vacuum pump impeller rotates, the centrifugal force creates a liquid ring concentric to the periphery of the protective cover which makes the compression.
The eccentric assembly of the impellet with respect to the cover leads to an increased gap between the blades of the impeller at the inlet of the system and a small space to the outlet. When the gas comes in, is enclosed between the impeller blades and the liquid ring. When the impeller rotates, the liquid ring compresses the gas and pumps it out of the ring.
Liquid ring not only acts as a seal, but it also absorbs the heat of compression, friction and condensation. In principle, any liquid can be used but is commonly used water, oil, glycol or other liquids that not vaporize at process conditions.
The main advantages of liquid ring vacuum pumps are the following:
- Simpler design than the most other vacuum pumps, only use a rotation system.
- May be made of any casting metal.
- Small noise and vibration.
- Very little increase in the discharge gas temperature.
- May handle loads condensable gases.
- Not any deterioration occurs due to liquid or small particles that in the process fluid.
- Small rotational speed (1800 rpm or less), which maximizes the processing time.
- It can be operated continuously or stop.
- Can be used any type of liquid as sealant fluid, in situations where there is a possible mixing with process steam.
Monoblock Vacuum Pumps
Vacuum Pumps, one and two stages
High capacity Vacuum Pumps