Positive Displacement Pumps

Edelmann is a Distributor of Positive Displacement Pumps for Industrial and food processing from Viking Pump, Wilden, Liquiflo, Wrightflow Technologies, Liberty Process, Seepex and Neptune.

Positive displacement pump types include: gear, lobe, piston, diaphragm, peristaltic, screw, progressive cavity, hydraulic and many others. Their advantages are:

  • Pump high viscosity (thick) fluids with ease, more efficiently than centrifugal.
  • Pump liquefied gases, shear sensitive fluids and medium viscosity liquids as well
  • Maintain consistent output flow rates with varying inlet and discharge pressure conditions
  • Most are self priming and can handle liquids with entrained vapor
  • Available in Mag Drive seal-less configurations

Positive Displacement pumps operate by using a rotary, reciprocating, or diaphragm method of drawing fluid into the pumping chamber at the inlet and pushing it through a discharge outlet.  Positive Displacement pumps move fluid at a constant rate regardless of pressure conditions, and they are typically the preferred choice for low to moderate flow rates at higher discharge pressures.

photo courtesy of processprinciples.com

Contact Us using the form on the right for assistance selecting the right Positive Displacement Pump Type >>>

Featured below are the primary Positive Displacement Pumps manufacturers that Edelmann & Associates sells and services.


Viking Pump – Gear, Vane & Lobe Pumps

  • Available in multiple technologies including Internal Gear, External Gear, Rotary Vane and Rotary Lobe
  • Capacities up to 1,600 gpm
  • Pressures up to 2,500 psi
  • Temperature range: -120°F to 800°F
  • Viscosity range of 0.5 to 440,000 cSt (28 to 200,000,000 SSU)
  • Materials of construction include cast and ductile iron, steel, 316 stainless steel, and PVDF
  • Many unique design features for a wide range of challenging applications
    • Externally adjustable end clearances
    • Pumps accommodate many different mechanical seal types
    • Mag Drive options to eliminate shaft seals
    • Fully jacketed options for products like asphalt
    • Electrically heated pumps
    • Abrasive Liquid pump options
    • Heavy duty and general purpose pump designs
  •  Accessories
    • Viking Pump Lead Ease and Eaton Duplex Basket Strainers for pump protection
    • Gear Reducers and complete pump systems
    • Duplex Fuel Oil Systems
    • Replacement Parts Kits

Viking Pump Internal Gear Cutaway

Viking Pump Internal Gear – Cutaway



  • Wilden Air Operated Double Diaphragm Pumps are ideal for a wide variety of liquid and slurry transfer applications
  • Can handle flow rates up to 350 gpm.
  • Temperatures up to 350°F
  • Commonly used on self-priming sumps, slurries, seal coat equipment, and chemical dispensing units.
  • Efficient air distribution (air valve) technology for lower total cost of ownership
  • Anti-freezing, lube-free air valves
  • Available in bolted or clamp band construction
  • Ideal for large solids handling up to 1 3/8″ size
  • Portable and submersible
  • Simple design with fewer parts vs the competition
  • Multiple port configurations available including NPT, flanged and sanitary
  • Replacement parts kits available
  • Sizes: 1/4″ to 4″
  • Materials
    • Aluminum
    • Ductile Iron
    • Stainless Steel
    • Alloy C
    • Polypropylene
    • PVDF

Positive Displacement Pumps

Wilden Air Operated Double Diaphragm Pumps



  • Designed for flow rates up to 55 gpm and differential pressure up to 350 psi, they
  • Handle fluids with viscosities from 0.3 to 100,000+ cP.
  • We also carry complete repair kits, cartridges, and offer options such as temperature control jackets, gear reducers, variable speed drives, air motors, and more.
  • Specializes in the design and manufacture of high-alloy gear pumps for chemical transfer
  • Applications such as acids, caustics, corrosive chemicals, solvents, polymers and hazardous liquids
  • Large selection of mag drive and mechanically sealed pumps
  • Materials of construction include corrosion resistance of 316 Stainless Steel, Hastelloy-C, Alloy-20, Titanium and PFA lined
  • Capacities up to 55 gpm
  • Differential pressures to 225 psi
  • Viscosities: 0.3 cP to 5,000 cP
  • Low pulsation design is ideal for metering applications
  • Easy to maintain – repair kits available which contain items to completely and easily rebuild all pumps to like-new condition



Liquiflo Centrifugal Pump Selection


Wrightflow Technologies

  • Circumferential piston and rotary lobe pumps designed for no metal to metal contact in the product for longer mean time between failure
  • Gentle pumping action on shear sensitive liquids or slurries with soft solids
  • Capacities up to 836 gpm
  • Differential pressures up to 500 psi
  • Viscosity to 910,000 SSU (200,000 cSt)
  • Temperature -40° to 300° F (-40° to 150° C)
  • Mechanical seals or O-ring seals
  • Rebuild kits available
  • Parts interchangeable with Waukesha Universal I and II

Wrightflow-Technologies-Sanitary-Pump-tra20Wrightflow Technologies Sanitary Pump TRA20


Liberty Process Logo

A Liberty Process progressive cavity pump is used when the pumping application is not suited to a centrifugal pump. This includes:

  • Higher viscosity liquids
  • Sheer sensitive liquids
  • Abrasive liquids
  • Application requires varied flow
  • When lower Net Positive Suction Head (NPSH) is needed

A Liberty Process progressive cavity pump ideal for liquids with higher viscosities or thickness.  A progressive cavity pump will have about the same flow for any liquid viscosity. The mechanical efficiency and volumetric efficiency goes up when the viscosity increases, with lower power and more flow. If you have a pumping application where you need a constant flow, but the liquid viscosity is variable and will change, then the PC pump is an ideal choice.

A progressive cavity pump is good when the application requires a varied flow. A progressive cavity pump has a precise flow per revolution of the pump. It is therefore quite easy to regulate the pump flow by just simply regulating the pump speed. Modern pump speed controllers like variable frequency drives (VFD’s) are well suited to be used with progressive cavity pumps for varying pump speed and flow control.

Another good application for a progressive cavity pump is when the suction conditions of the pumping applications are not ideal. A progressive cavity pump requires much lower Net Positive Suction Head (NPSH) as compared to a centrifugal pump because the internal pump velocity is lower. A progressive cavity pump can pump when the suction pressure is as low as 28″ of mercury (Hg), a centrifugal pump cannot do this. A progressive cavity pump will easily fill and pump in difficult applications when a centrifugal pump will not.

Progressive cavity pumps are ideal for applications where the liquid is sheer sensitive again because of lower internal velocity. A good example would be pumping oil and water mixtures to separation devices. The separation device works much better when the oil droplets are larger. A progressive cavity pump will not change the oil droplets where a centrifugal pump will emulsify the oil and make the oil droplets very small and reduce the separation performance of the separator.

A progressive cavity pump is good to use when the liquid contains abrasive solids. Most other types of positive displacement pumps can’t pump solids very well or for very long due to their close tolerances and all metal designs. A gear pump or vane pump will simply wear out when solids are present in the liquid and the same would also happen to most centrifugal pumps and they could clog. A progressive cavity pump is designed to last longer than all other pumps on abrasive applications. The pump design with the rotor and stator is the heart of the pump design for abrasion resistance. The internal velocity of the liquid as it travels through the pump is much lower than other types of positive displacement pumps and centrifugal pumps and the rubber stator.


Neptune diaphragm metering pumps are used for reliable chemical dosing for almost any industry and are available for high and low pressure applications with manual and electronic stroke control for precise product metering.  Additional accessories from Neptune include mixers, injection quills and sample coolers, just to name a few.

Hydraulic 500 Series
Provides leak-free metering of a wide variety of corrosive, flammable or hazardous liquids.
  • Features & Benefits:
    • Innovative designs for precision and long-term reliability
    • Valve cartridges are double ball check design and can be removed without disturbing piping
    • Variable oil by-pass™ stroke adjustment for better valve performance
    • Capacity adjustable by micrometer dial while pump is running or stopped
    • Bright color contrasted ideal protected from corrosion by clear PVC covering
    • Motor driven for precise injection
  • Technical Data:
    • Liquid end materials: 316 SS, PVC, PVDF or Alloy 20
    • Motor data: integral motors standard, D-flange (IEC) and
    • (NEMA) c-frame mountings are available
    • Motor options: Explosion-proof, wash down duty, VFD
  • Performance Data:
    • Capacity/Flow @60Hz: 0.2 GPH ( 0.757 L/H) to 97 GPH ( 370 L/H)
    • Duplex head@60 Hz to: 194 GPH ( 730 L/H)
    • Capacity/Flow @50Hz: 0.17 GPH ( 0.631 L/H) to 81 GPH (306 L/H)
    • Duplex head@50 Hz to: 162 GPH ( 610 L/H)
    • Max. pressure: 207 bar ( 3000 psi)
PZ Series Feature an air release valve that allows the pumps to be used in sodium hypochlorite service or with other chemicals that off-gas at room temperature.
  • Features & Benefits:
    • Leading pulse metering pump design
    • Operates on any single phase voltage from 94 VAC to 264 VAC
    • Manual stroke length adjustment (Models: PZi4, PZi8, PZiG)
    • Digital setting option can set stroke speed, discharge volume or by percentage
    • Timer and batch functions built-in (Models: PZi8, PZiG)
    • 1 to 300 spm (max) speed allows wide turndown range
  • Technical Data:
    • PVC, acrylic, stainless steel and PVDF models available
    • Manual, 4-20 mA or pulse input control
    • Models for high viscosity available
    • Automatic degassing valve for chemicals that off-gas
    • External Interlock Available (remote start, level switch, reset)
  • Performance Data:
    • Capacity/Flow @ 60Hz” 0.44GPH (2L/H) to 20.6Gph (80 L/H)
    • Max. pressure: 15.1 Bar (220psi)
  • Accessories Available:
    • Injection Quill
    • By-Pass Feeders
    • Sample Coolers
    • Corporation Stops
    • Glycol Feeders
    • Back Pressure Valve & Pressure Relief Valves
    • Calibration Columns

At Edelmann & Associates, we know Positive Displacement Pumps


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