A few words about the PW vacuum pumps
In industrial plants many processes are performed with the pressure lower than the atmospheric pressure, commonly referred to as “vacuum”. Apart from non-condensable gases the vacuum pumps generating it must pump vapours or together with gas they pump small amounts of liquids, which implicates application of special pumps - vacuum pumps with a rotary liquid ring. Since water is in the majority of instances the working liquid (forming the ring) these pumps are very often called water-ring (PW). Since these pumps are filled up with liquid, small amounts of the liquid or vapour that are in the pumped gas are harmless of course – as opposed to the pumps with different construction, e.g. piston or blade.
The PW pumps have found applications, i.a., in:
- priming of liquid levers and centrifugal pumps that do not feature self-priming properties
- vacuum drying and wood vacuum finishing
- production of Styrofoam
- production of vegetable oils
- production of paper
- performance of chemical processes (chemical industry, petroleum industry, pharmaceutical industry and many other).
From the point of view of the maintenance services these pumps have many advantages, i.a.:
- a simple, compact construction
- reliable operation
- working space does not require lubrication.
Yet another important advantage of these pumps is safety of work in the explosion hazard zone and at pumping flammable, explosive gases. The pumps are provided with the EC Compliance Certificate i.a. in the range of Directive ATEX No. 2014/34/UE. The anti explosiveness II 2G IIB T3-T4 – Category 2 (1 zone of explosion hazard) concerning both the pump interior as well as the place of installation.
Application of non-combustible working liquid (water, glycol) assuring its constant inflow and making the pump working space from intrinsically safe materials (copper alloys, acid resistant steel/cast steel) ensure its safe operation.
The pumps in the intrinsically safe executions have been applied, i.a., at the Coal Mine Methane Extraction Plants (they pump methane) and at encapsulation of fuel stations (they pump hydrocarbon vapours).