Nantong Zhongtian Machinery Manufacturing Co., Ltd. (ZT Pumps) manufactures industrial liquid ring vacuum pumps for wet gas, condensable vapor and process vacuum applications. Seven series cover pumping speeds from 18 to 10,100 m³/h, with single-stage, double-acting and two-stage configurations.
A liquid ring vacuum pump is a rotating positive-displacement machine that uses a rotating impeller and a ring of liquid — typically water — to create compression chambers and generate vacuum. As the impeller rotates eccentrically within the casing, the liquid ring forms a seal between the impeller blades, creating cells that expand on the suction side and compress on the discharge side.
Liquid ring pumps are well suited to wet gases and condensable vapors and can tolerate limited liquid carryover when properly selected for the operating conditions. This makes them a practical choice for vacuum drying, distillation, solvent recovery and other process vacuum applications where dry vacuum technology would require upstream condensers or separators.
The sealing liquid — most commonly water — is continuously supplied, circulated and discharged through a separator. In closed-loop configurations, the working liquid is recirculated with heat exchange, reducing water consumption and enabling use of process-compatible sealing liquids.
Seven series covering single-stage, double-acting and two-stage configurations. All series are manufactured at our Nantong facility and available for OEM supply.
Single-Stage Liquid Ring
Compact single-stage direct-coupled liquid ring vacuum pumps. Robust construction suited to chemical processing, paper and food industries. Available in standard and corrosion-resistant (F) configurations.
Single-Stage Liquid Ring
Single-stage direct-coupled liquid ring vacuum pumps with lower ultimate pressure than the SZ series. Suitable for general industrial process vacuum, vacuum drying and vacuum concentration.
Single-Stage Liquid Ring
Single-stage liquid ring pumps with standard 2BVA or stainless steel 2BVF construction. Compare both configurations, model specifications and product photographs on one page.
Single-Stage Double-Acting Liquid Ring
Single-stage double-acting liquid ring vacuum pumps for high-capacity industrial vacuum applications. Symmetric double-acting design provides balanced hydraulic loading.
Single-Stage Double-Acting Liquid Ring
Large-capacity single-stage double-acting liquid ring vacuum pumps. Multiple frame sizes (2BE151, 2BE152, 2BE153, 2BE202, 2BE203, 2BE252) for high-volume industrial vacuum in paper, chemical and power generation applications.
Two-Stage Liquid Ring
Two-stage liquid ring vacuum pumps designed to maintain stronger pumping performance at lower inlet pressures. Suitable for chemical, pharmaceutical and food-processing vacuum applications requiring stable performance in the higher-vacuum operating range.
| Series | Type | Pumping Speed | Ultimate Pressure (Absolute) | Configuration | Typical Applications |
|---|---|---|---|---|---|
| SZ / SZ(F) | Single-stage | 18–216 m³/h | 4,000 Pa | Direct-coupled | Chemical, paper, food processing |
| LD / LD(F) | Single-stage | 28.8–216 m³/h | 3,300 Pa | Direct-coupled | Process vacuum, vacuum drying, concentration |
| 2BVA / 2BVF | Single-stage | 27–499.8 m³/h | 3,300 Pa | Direct-coupled / Support-frame; standard 2BVA / stainless steel 2BVF | General industrial process vacuum; 2BVF for compatible corrosive media |
| ZTS / ZTS(F) | Single-stage double-acting | 600–720 m³/h | 3,300 Pa | Coupled | High-capacity industrial vacuum |
| 2BE | Single-stage double-acting | 300–10,100 m³/h | See model/configuration specifications | Direct / Belt | Paper, chemical, power generation |
| 2S / 2S(F) | Two-stage | 90–1,800 m³/h | 3,300 Pa | Coupled | Chemical, pharmaceutical, food processing |
Published performance values are based on the listed series data. Actual attainable vacuum depends on sealing-liquid temperature, gas composition, vapor load and operating conditions.
Correct pump selection requires a complete set of operating conditions. Provide the following parameters for an accurate recommendation:
Vacuum distillation, vacuum concentration, solvent recovery and reactor evacuation.
Drying of heat-sensitive materials at reduced pressure and temperature.
Separation of mixtures with high boiling points or thermally sensitive components.
Recovery of solvents from process streams in chemical and pharmaceutical plants.
Vacuum frying, vacuum packaging and vacuum concentration of food products.
Vacuum drying, filtration and evaporation in pharmaceutical manufacturing.
Degassing and vacuum calibration in plastic extrusion lines.
Industrial vacuum filtration in mining, chemical and water treatment.
General industrial process vacuum for manufacturing and utilities.
Concentration of solutions under vacuum in food, chemical and pharmaceutical industries.
The sealing liquid can cool the gas and condense or absorb part of the condensable vapor during compression, allowing continuous operation with high moisture and vapor loads without liquid accumulation in the casing.
Liquid ring pumps can tolerate moderate liquid carryover in the gas stream — a significant advantage in vacuum drying, distillation and filtration applications.
The impeller is the only moving part in contact with the process gas. There are no valves, pistons or complex timing mechanisms, which simplifies maintenance.
Heat of compression is absorbed by the sealing liquid, keeping gas temperatures low. This is beneficial for thermally sensitive gases and vapors.
Single-stage designs achieve approximately 3,300–4,000 Pa absolute, covering the vacuum range used in many industrial drying, distillation and concentration processes.
Water is the most common sealing liquid, but glycol, solvents or process-compatible liquids can be used in closed-loop systems where contamination of the sealing water must be avoided.
A multi-blade impeller rotates eccentrically within a cylindrical casing. Sealing liquid — typically water — is introduced into the casing.
Centrifugal force throws the liquid outward, forming a rotating ring against the casing wall. The eccentric position of the impeller creates cells of varying volume between the impeller hub and the liquid ring.
As the impeller rotates, cells on the suction side expand. Gas is drawn in through the inlet port in the end plate.
As rotation continues, cells on the discharge side decrease in volume, compressing the gas. Compressed gas is discharged through the outlet port. The sealing liquid is separated and recirculated or discharged.
For applications requiring higher pumping speed at intermediate vacuum levels, deeper vacuum than a single-stage liquid ring pump can achieve, or reduced water consumption, a system approach is often more appropriate than a single pump.
Integrates the liquid ring pump with a gas-liquid separator, working-liquid recirculation circuit and heat exchanger. Reduces water consumption and allows use of process-compatible sealing liquids for solvent recovery and pharmaceutical applications.
View Closed-Loop SystemsA Roots booster upstream of a liquid ring backing pump significantly increases pumping speed at intermediate vacuum levels. ZT Pumps supplies Roots + liquid ring systems as skid-mounted units with integrated controls.
View Roots Vacuum SystemsNantong Zhongtian Machinery Manufacturing Co., Ltd. has manufactured industrial vacuum pumps since 2002, with liquid ring pumps as a core product line.
ZT Pumps supplies OEM and ODM vacuum pumps to equipment manufacturers. Custom configurations, labeling and documentation are available for qualified OEM customers.
ZT Pumps products are supplied to distributors and OEM customers in over 50 countries. Engineering documentation is available in English.
Quality management system certified to ISO 9001. Manufacturing processes and product quality are managed under a documented quality system.
Technical support for pump selection, system design and application engineering is available from the ZT Pumps engineering team.
ZT Pumps works with authorized distributors in key markets. Regional distributors provide local sales, technical support and spare parts supply.
The terms are used interchangeably. "Water ring" refers to the most common sealing liquid — water. "Liquid ring" is the technically broader term, as other liquids (glycol, solvents, process liquids) can be used as the sealing medium depending on the application.
Single-stage liquid ring pumps typically achieve ultimate pressures of approximately 3,300–4,000 Pa absolute (33–40 mbar) under standard conditions. Two-stage designs (such as the 2S series) can reach similar ultimate pressures with improved performance at intermediate vacuum levels. Actual attainable vacuum depends on sealing-liquid temperature, gas composition and vapor load.
The ultimate pressure of a liquid ring pump is limited by the vapor pressure of the sealing liquid. As sealing water temperature increases, its vapor pressure rises, raising the minimum achievable absolute pressure. Colder sealing water allows deeper vacuum. For demanding applications, a heat exchanger in the sealing water circuit is recommended.
Yes. Liquid ring vacuum pumps are well suited to handling wet gases and condensable vapors. The sealing liquid can cool the gas and condense or absorb part of the vapor during compression. Actual performance depends on vapor load, sealing-liquid temperature and operating pressure, so high-vapor processes may benefit from upstream condensation.
Key parameters include required pumping speed (m³/h) at operating pressure, operating absolute pressure, gas composition and inlet temperature, condensable vapor load, sealing liquid temperature, required construction material, power supply frequency and installation altitude. ZT Pumps provides engineering support for pump selection — use the Pump Selector or submit your operating conditions directly.
A Roots booster (Roots vacuum pump) is added upstream of a liquid ring backing pump when higher pumping speed at intermediate vacuum levels is required, or when the process demands vacuum deeper than a liquid ring pump alone can achieve. The liquid ring pump handles the gas discharge from the Roots booster. ZT Pumps supplies Roots + liquid ring vacuum systems as integrated skid-mounted units.
Standard 2BVA and SZ/LD series use cast iron construction. The 2BVF series provides full corrosion-resistant construction with stainless steel wetted parts. For specific corrosive media, material suitability depends on the gas composition, concentration and temperature — contact ZT Pumps engineering for material selection guidance.
Submit your operating conditions and our engineering team will recommend the appropriate series and model.
Useful information to include: Flow / Pumping Speed · Operating Pressure · Gas Composition · Gas Temperature · Application · Power Supply
