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The LD / LD(F) Series consists of single-stage, single-acting liquid ring vacuum pumps featuring a compact horizontal direct-coupled design. The impeller is mounted directly on the motor shaft, resulting in a simple structure, compact footprint and convenient maintenance. LD models are designed for general industrial vacuum applications, while LD(F) models are corrosion-resistant versions developed for compatible chemical and process media. Using water as the standard operating liquid, the series is particularly suitable for handling air, water-vapour-rich gases and compatible process gases. With an ultimate pressure down to 3300 Pa under specified test conditions, LD / LD(F) pumps are widely used for vacuum drying, distillation, concentration, degassing, filtration and other industrial process-vacuum applications. They can also be used as backing pumps for Roots vacuum booster systems.
Working Principle
The LD / LD(F) Series operates on the liquid-ring principle. An eccentrically mounted impeller rotates inside the pump casing containing a controlled amount of operating liquid, typically water. Centrifugal force forms the operating liquid into a rotating ring along the inner wall of the casing. Because the impeller and liquid ring are eccentric to each other, the spaces between the impeller blades and the liquid ring continuously change in volume. Increasing chamber volume draws gas into the pump, while decreasing chamber volume compresses the gas and discharges it through the outlet. The liquid-ring compression process produces relatively low gas-temperature rise and is particularly suitable for handling wet gases and gas streams containing large amounts of water vapour. Vacuum performance is influenced by the temperature and vapour pressure of the operating liquid. Lower operating-liquid temperatures generally improve achievable vacuum and pumping performance.
Key Features
Corrosion-Resistant Options
LD(F) models are corrosion-resistant versions of the standard LD Series, developed for compatible chemical and process applications where enhanced material resistance is required. Full 304 and 316 stainless steel configurations are available for compatible corrosive process applications. Material selection should be confirmed according to the process medium, concentration, operating-liquid chemistry, temperature and actual operating conditions.
Motor Options
Standard and explosion-proof motor configurations are available according to application requirements.
LD = Standard Version
LD(F) = Corrosion-Resistant Version
Standard LD and corresponding LD(F) models share the same basic performance specifications unless otherwise specified.
*Performance values are based on factory test conditions at one standard atmosphere, using water as the operating liquid at 15°C. Actual pumping performance and ultimate pressure may vary with operating-liquid temperature and process conditions.
*Corrosion-resistant LD(F) configurations and explosion-proof motor options are available according to application requirements.
Typical Applications
vacuum distillation, evaporation, concentration and drying. LD(F) corrosion-resistant configurations available.
vacuum drying and compatible process-vacuum applications
vacuum degassing and molding processes
vacuum concentration and compatible wet-process applications
vacuum filtration and industrial dewatering processes
backing pump service for Roots vacuum booster systems