Liquid Ring Vacuum Pumps for Wet and Vapor Duty
Rugged vacuum for wet, dirty, and condensable loads, sized and serviced from 14 Midwest locations.
Is a liquid ring pump right for my process?
A liquid ring vacuum pump is the right choice when the gas stream is wet, condensable, or carries liquid and particulate. Its sealing liquid absorbs heat and tolerates carryover that would foul or wear a dry pump, and it can even condense some vapor in the pump. For clean, dry duty a rotary vane or claw pump is more efficient. Tell us the vacuum level, flow, and what is in the stream and Brabazon will size the pump and its seal water arrangement.
How a liquid ring pump works
A liquid ring pump spins an offset impeller inside a casing partly filled with a sealing liquid, most often water. Centrifugal force throws the liquid outward into a ring that follows the casing wall, and because the impeller sits off center that ring moves toward and away from the hub as it rotates. The spaces between impeller blades therefore grow and shrink, drawing gas in through the inlet port and compressing it out through the discharge, in effect acting like a set of small liquid sealed pistons. The sealing liquid does double duty: it forms the seals and it carries away the heat of compression, which is why the pump tolerates wet and dirty gas so well and even condenses some incoming vapor.
When to specify liquid ring vacuum
Specify a liquid ring pump when the process throws off moisture, solvent vapor, or entrained liquid, or when the stream carries carryover that a dry pump cannot survive. Typical fits include evaporation and distillation vacuum, filtration and dewatering, vapor recovery, and many food, chemical, and process duties where the gas is saturated. The pump is also a good choice for dirty environments because the liquid ring flushes contaminants through with the discharge rather than letting them build up on dry running surfaces. Where the process needs a deeper vacuum than a single stage pump provides, a two stage pump or an added booster extends the range.
Sizing and seal water considerations
Size a liquid ring pump to hold the target vacuum at the real gas load, and treat the sealing liquid as part of the sizing. Because the ultimate vacuum is limited by the vapor pressure of the seal water, its temperature directly sets how deep a vacuum the pump can pull: colder seal water lowers that floor and buys you more vacuum. Include the condensable vapor load in the capacity calculation, since vapor that condenses in the pump adds heat the seal water must remove. Decide early whether the seal water runs once through, partially recirculated, or in a closed loop with a heat exchanger, because water use, discharge, and process compatibility all turn on that choice. Add realistic leakage and outgassing as with any vacuum job, and confirm the pump reaches and holds the working point with margin.
Service and failure considerations
Liquid ring pumps are tolerant machines, but they depend on clean, correctly cooled sealing liquid. Scaling, fouling, or dirty seal water is the leading cause of lost vacuum, so treat and monitor the seal water and keep the heat exchanger clean. Corrosion and erosion matter when the gas or liquid is aggressive, and material selection should match the process. Watch for cavitation when the pump runs near its vacuum limit with warm seal water, since that erodes the impeller over time. Bearings, mechanical seals, and clearances round out the wear items. Our technicians rebuild and service liquid ring pumps and their seal systems in the shop and in the field.
Liquid ring pump lines available through Brabazon
Brabazon supplies liquid ring vacuum pumps and packages from Becker, Airtech, Dekker, and Global Vac. We size the pump and its seal water arrangement to your vacuum level, flow, and gas stream, then support it with parts and service.
Liquid ring vacuum pump questions, answered first
How does a liquid ring vacuum pump work?
A liquid ring pump spins an offset impeller inside a casing partly filled with sealing liquid, usually water, which the impeller throws into a rotating ring against the wall. That liquid ring forms moving seals between the impeller blades, so as the ring recedes and returns it draws gas in and compresses it out, much like a series of small pistons. Because the sealing liquid absorbs heat and tolerates carryover, the pump runs cool and handles wet, dirty streams well.
When should I choose a liquid ring pump over a dry pump?
Choose a liquid ring pump when the gas stream is wet, condensable, or carries liquid and particulate. Those loads foul or wear a dry pump quickly, but a liquid ring pump absorbs them because its sealing liquid handles heat and carryover and can even condense some vapor in the pump. For clean, dry duty a rotary vane or claw pump is more efficient, so the deciding factor is whether the stream is wet or dirty.
What sealing liquid does a liquid ring pump use?
Most liquid ring pumps use water as the sealing liquid, supplied once through, partially recirculated, or in a closed loop with a heat exchanger. The sealing liquid temperature sets the achievable vacuum, because colder liquid lowers the vapor pressure in the pump and lets it pull a deeper vacuum. Where water use or the process fluid matters, the seal system can be arranged to recover and cool the liquid. We size the seal water arrangement along with the pump.
How deep a vacuum can a liquid ring pump reach?
A single stage liquid ring pump typically reaches a moderate vacuum limited by the vapor pressure of its sealing liquid, and colder seal water lets it pull deeper. Two stage designs reach further, and a liquid ring pump can be backed by a booster for deeper duty. Because the sealing liquid vapor pressure sets the floor, the ultimate vacuum depends heavily on seal water temperature. Tell us your target vacuum and we will confirm the arrangement.
Talk to a vacuum engineer about your wet duty
Send your vacuum level, gas load, and seal water conditions and an engineer will size the right liquid ring pump, then quote sale, rebuild, or service. We answer 24/7.
Request a liquid ring vacuum pump quote
Tell us your vacuum level, gas stream, and seal water conditions and a specialist will size and quote the right pump. Or call 800.825.3222, answered 24/7.
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