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Designing Reliable Dry Screw Vacuum Pumps

Dry vacuum pump technology – especially variable pitch screw chemical dry pumps – offer clear, measurable advantages in a wide variety of essential applications. A properly designed dry screw vacuum pump ensures the processing needs are accomplished with a safe, reliable, and cost-effective solution.

Dry screw vacuum pumps require no water or oil for sealing or lubrication in the vacuum stages. Consequently, these dry vacuum systems eliminate effluent generation, pollution, and high treatment costs. This reduces or eliminates waste disposal costs and plants achieve savings in maintenance costs.

Principle Of Operation For Dry Screw Vacuum Pumps

  • A dry screw vacuum pump consists of two parallel, screw-shaped rotors (1 and 2), one with a right-hand thread and the other with a left-hand thread.
  • Both screws turn in the compression housing (9) without friction and at very tight clearances. They are synchronized via a precision gear (3).
  • The compression housing and the special shape of the screws form compression chambers (4).
  • Due to the opposite rotation of the screws, the chamber connected with the suction port (5) is enlarged and the gas is transported into the compression chamber. Then, the chamber moves axially from the suction side to the pressure side (arrow).
  • In variable pitch models, the gas is compressed at each pitch change and cooled before the next pitch change, resulting in greater efficiency.
  • On the pressure side, the chamber is moved against the axial housing wall and the volume is reduced until the front surface of the screw (1) opens the pressure channel (6) and the compressed gas is discharged through the pressure connection (7).
  • Cooling is achieved using a water-cooled outer chamber (8). Gas ballast port available for application-specific solutions (10).

Benefits Of Dry Screw Vacuum Pumps

Dry screw vacuum pumps have proven their value and reliability since the late 1980s. In today’s world of environmental regulations, safety issues and production costs offer numerous advantages such as:

  • No contamination of process streams
  • No effluent, no pollution, minimized or no waste disposal expense
  • Deeper vacuum and more flexible operation
  • Capacities not limited by cooling water temperatures
  • Tolerant to heat load
  • Pump explosive gases safely
  • Lower cost of ownership
  • Extended service intervals and bearing life
  • Low power consumption in operating range. Hence, more energy-efficient in terms of m3/hr-1/ kW-1 compared to steam ejectors and liquid ring pumps
  • No contaminated water or oil
  • No contaminated effluent
  • No process contamination

Learn More About Dry Screw Vacuum Pumps In This Animation From Gardner Denver Nash

Dry Screw Vacuum Pumps Handle Tough Industrial Applications

Dry screw vacuum pumps deliver a clean, oil-free vacuum for a variety of industrial applications. These systems perform with low rotational speed ensuring smooth and robust operation. Higher discharge pressure capabilities along with a high tolerance for vapor and dust guarantee more process time with long service life.
Furthermore, dry screw vacuum pumps safely and reliably handle corrosives, organics, inorganics, and solvents. Thus, making dry vacuum systems ideal and well suited to serve the following market segments:

  • Fine and Specialty Chemicals - This includes a range of products such as adhesives, agrochemicals, oil field chemicals, flavors and fragrances, additives, cosmetics, fluids and lubricants, food, paper, paints, coatings, printing inks and more.
  • Pharmaceuticals - Many in the industry were early adopters of dry vacuum systems for intermediates and active pharmaceutical ingredients.
  • Petrochemicals - Applications for downstream processes are noteworthy such as aromatics extraction, fibers, paints, polymerization reactions, plastics, resins, and waste oil recycling.
  • Oleochemicals -Typical products include pharmaceutical ingredients, vitamins, monoglycerides, additives, preservatives, esters, biofuels, glycerine, fats, and oils, (fatty acids, amines, and alcohols), antioxidants, surfactants, and bioplastics. Typical processes include distillation, drying, evaporation, filtration, concentration, deodorization, deareating, food processing, and vapor impregnation.
  • Emerging Applications - Emerging applications including lithium-ion battery manufacture, biodegradable polymers, and fuel vapor recovery are also good candidates for a dry vacuum system.

Trusted Experts

Gardner Denver Nash offers an established history of engineering expertise in designing and delivering safe, reliable wet and chemical dry vacuum systems. Our pumps have met the needs of harsh industrial environments. Its experience in chemical, pharmaceutical, petrochemical, and other industries solve the most demanding challenges.


ISO Certified

Nash manufacturing and service facilities are ISO 9001, ISO 14001 and OHSAS 18001 certified.

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