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Liquid Ring Vacuum Pumps

Liquid ring vacuum pumps (LRVPs) create dependable gas removal for wet and condensable gas streams in industrial vacuum service, including steam condenser air removal, process vacuum applications, and hybrid steam jet vacuum systems.

Overview

Liquid Ring Vacuum Pumps, Engineered to Your Process.

Liquid ring vacuum pumps have a long record in industrial vacuum service, particularly where the gas stream contains moisture, condensables, or non-condensable gases that must be removed continuously from process equipment. Their internal compression mechanism uses a circulating liquid seal rather than dry-running clearances, giving the technology a strong tolerance for wet gas conditions that may challenge other mechanical vacuum equipment. That tolerance extends to occasional liquid carryover, which is a common failure point for dry-running vacuum technologies.
These pumps handle steam surface condenser air removal, vacuum distillation, evaporation, filtration, drying, and deaeration. They fit best where stable gas handling matters more than oil-free dry compression or extremely deep standalone vacuum.
In Artisan vacuum systems, LRVPs are frequently paired with steam jet ejectors in hybrid steam jet vacuum systems. The pump handles the final vacuum duty while the upstream ejector stages extend the operating range beyond what an LRVP would achieve alone. This arrangement is especially useful where deeper vacuum levels are required and the facility must also manage steam consumption, installation footprint, or utility balance.
The vacuum capability of a liquid ring pump is influenced by the vapor pressure of the seal liquid at the operating temperature. When that physical limit becomes a constraint, Artisan applies JET-VAC® and Unique Systems® vacuum experience to integrate LRVPs with steam jet technology, condensers, controls, and skidded equipment for a more complete system approach.

Applications

Steam condenser air removal · Industrial process vacuum · Non-condensable gas removal · Hybrid steam jet vacuum systems · Turbine condenser hogging · Holding mode operation · Wet gas handling · Condensable gas service · Utility vacuum systems

Industries Served

Power & Energy · Chemical · Petrochemical · Refining · Food & Beverage · Pharmaceutical · Nutraceutical · Edible Oils · Waste Reduction · Industrial Processing

Vacuum Heritage

Artisan’s liquid ring vacuum pump capabilities are rooted in decades of JET-VAC® and Unique Systems® experience across hybrid steam jet vacuum systems, vacuum pump exhausters, and turbine condenser air-removal packages. Today, that heritage is integrated into Artisan’s engineering and manufacturing resources in Stoughton, MA.

Liquid Ring Vacuum Pump Systems

A liquid ring vacuum pump contains an eccentrically mounted rotor assembly turning inside a cylindrical casing partially filled with seal liquid. Centrifugal force forms the liquid into a ring around the casing wall, while the offset rotor impeller creates expanding and contracting spaces between the blades and the liquid ring. Gas enters as these spaces expand, undergoes compression as their volume decreases, and exits through the discharge port.
Water is the most common seal liquid, although compatible process liquids may be selected where water contamination is undesirable or vapor recovery favors a closed-loop arrangement. Seal liquid vapor pressure and inlet temperature, gas composition, and condensable load all influence pump capacity and ultimate vacuum.
The discharged gas and seal liquid typically enter a separator, where the liquid is drained, partially recirculated, or cooled and returned in a closed loop. Because the separator handles the discharge stream, the arrangement does not require an aftercondenser. Reliable operation depends on proper seal liquid conditions, cavitation margin, and routine attention to seals, bearings, clearances, and separator performance. Electrical area classification also factors into pump and motor selection where the equipment sits in a classified location.

Liquid Ring Vacuum Pump Advantages

  • Handles wet and condensable gas streams in industrial vacuum service
  • Removes air and other non-condensable gases from process equipment
  • Straightforward operating principle with reliable continuous duty
  • Suitable as a final stage in hybrid steam jet vacuum systems
  • Available as part of skidded vacuum pump exhauster packages
liquid-ring-vacuum-pump-systems

Our engineering team can evaluate your gas load and target vacuum level to identify the right LRVP configuration.

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liquid-ring-vacuum-pump-systems

Hybrid Steam Jet Vacuum Systems

Hybrid steam jet vacuum systems combine one or more ejector stages with a liquid ring vacuum pump. The ejectors act as upstream boosters, raising the process gas to a pressure the LRVP can handle efficiently before the pump completes compression to atmospheric discharge.
This arrangement extends vacuum capability beyond the practical standalone range of the LRVP while lowering motive steam demand compared with an all-ejector system. Because the mechanical pump serves as the atmospheric stage, it can be installed at grade and discharge into a separator. That removes the elevated hotwell or barometric leg required by certain condensing ejector configurations.

Hybrid systems are well suited to changing process loads, cooling water temperatures, and utility conditions. A hybrid system may integrate ejectors, intercondensers, an LRVP, and separators, along with the piping, instrumentation, and controls needed for an application-specific skidded system.

Hybrid System Advantages

  • Combines steam jet ejectors with liquid ring vacuum pump technology
  • Extends vacuum capability beyond the practical range of an LRVP alone
  • Reduces motive steam consumption compared with an all-ejector system
  • Places the LRVP as the final stage of the vacuum system
  • Installs at grade without a barometric leg
  • Applicable where deeper vacuum levels and utility efficiency both matter
Hybrid steam jet vacuum system skid featuring an upper steam ejector with shell-and-tube condenser supported over a lower liquid-ring vacuum pump unit.
Our engineers can evaluate your steam availability and vacuum requirement to confirm whether a hybrid system fits.
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Hybrid steam jet vacuum system skid featuring an upper steam ejector with shell-and-tube condenser supported over a lower liquid-ring vacuum pump unit.

Condenser Air Removal Systems

Liquid ring vacuum pumps remove air and other non-condensable gases from steam turbine main surface condenser. If allowed to accumulate, these gases interfere with steam-side heat transfer and may increase turbine exhaust pressure.
During startup, the system evacuates the condenser from atmospheric pressure to the level required for turbine operation, a high-capacity duty known as hogging. Once operating pressure is reached, the system shifts to holding duty, continuously removing air, water vapor, and other non-condensables.

A typical condenser air removal system uses two identical 100% capacity pump skids, generally built around two-stage LRVPs with separators, seal water controls, bypasses, and automatic instrumentation. Both skids run during hogging; one then shuts down while the other holds. Condenser volume, air leakage, pumpdown requirements, cooling water conditions, and plant reliability criteria set the specifics.

Condenser Air Removal System Advantages

  • Removes air and non-condensable gases from steam surface condensers
  • Protects condenser heat transfer performance
  • Uses dual 100% capacity pump skids for hogging and holding operation
  • Operates both skids during condenser evacuation, then one during continuous holding duty
  • Maintains air removal during turbine operation
Our engineering team can align the air removal package to your condenser duty and the plant’s startup sequence.
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Pump Staging & Operating Modes

Liquid ring vacuum pumps are available in single-stage and two-stage configurations. The choice follows the vacuum level the process requires, the moisture content of the inlet stream, and whether the pump runs a short startup duty or continuous service.

Single-Stage Liquid Ring Vacuum Pumps

A single-stage pump performs suction, compression, and discharge within one impeller stage. Because all of the heat of compression and condensation goes into the liquid ring in that stage, the vapor pressure of the seal liquid sets the practical limit on both capacity and cavitation-free operation. Single-stage pumps are generally selected for moderate-vacuum service where the inlet stream is primarily dry air — simple hogger duty being the clearest example — and they hold a modest efficiency advantage over two-stage pumps in the shallower vacuum range.

Two-Stage Liquid Ring Vacuum Pumps

Two-stage pumps divide compression between two impellers on a common shaft, which lowers the pressure ratio and the heat load carried by the first stage. Running cooler, the first stage is significantly less prone to cavitation, and the pump sustains deeper vacuum than a comparable single-stage machine. The configuration was developed for condenser exhauster service and remains the standard choice for it.

In turbine condenser exhauster service, an interstage bypass may route flow around the second stage during hogging, when suction pressure and gas volume are higher. As condenser pressure falls, the bypass closes automatically and the pump transitions into two-stage holding operation. The transition is fully automatic and requires no operator action. The actual crossover pressure varies with pump design, seal liquid temperature, gas composition, and system resistance, and should be confirmed against manufacturer performance data.

Operating Mode Considerations

  • Single-stage pumps suit dry-air hogger duty at moderate vacuum levels
  • Two-stage pumps are the standard choice for continuous condenser exhauster service
  • First-stage operation is used at higher absolute pressures during hogging
  • Second-stage operation becomes efficient at deeper vacuum levels
  • Interstage bypass operation helps manage efficiency and peak horsepower demand
  • Bypass closure and the shift into two-stage holding operation are fully automatic
pump-staging-operating-modes
Our engineering team can review your startup sequence and continuous duty to determine whether a single-stage or two-stage pump fits.
Talk to an Engineer
pump-staging-operating-modes

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Have a Liquid Ring Vacuum Pump Application to Discuss?

Share the details of your vacuum application with Artisan’s engineering team, and we’ll help identify the right liquid ring vacuum pump or hybrid system approach for your operating conditions.

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(781) 893-6800

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