Ws+ Series (IEC) - Self-Priming Centrifugal Pumps

Product Type(s) : Centrifugal Pumps
Description :

Ws+ is a self-priming centrifugal pump



Reduce your noise level and benefit from the amazing development in self-priming. The self-priming Ws+ is designed to handle CIP (Clean In Place) return and other fluids with entrained air and foam. The unique design reduces the energy consumption and noise of traditional liquid ring pumps by using a high efficiency impeller that can be trimmed to match a specific duty. The Ws+ employs a built in eccentric air screw to form the liquid ring required for its self-priming capability.

  • 20-90% more efficient than other liquid rings due to improved fluid flow through pump.
  • Performance optimized by matching impeller size to duty.
  • Low noise level: Due to its hydraulic design the noise level of the Ws+ is significantly lower than traditional liquid ring pumps.
  • 3-A (optional) and EHEDG approved.
  • Interchangeable with W+ parts. Inventory is reduced by sharing common parts.
  • Less prone to damage. Small objects can pass through pump with minimal damage.

The pump is approved by the EHEDG (European Hygienic Equipment & Design Group) as a hygienic pump and is also approved according to the American 3-A standard (optional). Consequently the pump can be used as a CIP as well as a first class hygienic product pump.The Ws+ series consist of 3 pump sizes.

  • Ws+ 20/15
  • Ws+ 30/30
  • Ws+ 44/50

At 50 Hz the Ws+ operates at a maximum pressure of 6.5 bar (94 psi) and a flow capacity of 90 m3/hour (396 GPM), while the values for a pump with a 60 Hz motor is 9.5 bar (138 psi) and 110 m3/hour (484 GPM).  

Theory of Operation

Unique Design

The Ws+ employs a unique eccentric screw and recirculation loop to generate the liquid ring required to handle aerated product and produce a vacuum. The design allows the use of standard centrifugal components to match the pump to a specific duty point to produce efficiencies previously unobtainable with liquid rings. Impellers can be trimmed to further reduce horsepower requirements. The result is higher efficiency, decreased power consumption, simpler components and less noise.


  1. Fluid recirculation loop
  2. Impeller
  3. Eccentric Screw



The APV Ws+ uses a unique design that combines the abilities of most liquid ring pumps with the efficiencies of the W+ centrifugal series. As a result customers can now handle entrained air and lift requirements with lower power
consumption, less noise and at lower cost. 

The Ws+ employs a unique air screw, spinning in an eccentric arranged priming liquid chamber, and a recirculation loop to generate the liquid ring required to handle aerated product and produce a vacuum in the suction pipe. The design allows the use of standard centrifugal pump components to configure the pump to a specific duty point to produce efficiencies previously unobtainable with liquid rings. Impellers can be trimmed to further reduce power consumption.

The result is:

  • Higher efficiency
  • Decreased power consumption
  • Simpler components
  • Less noise


  1. Air Screw
  2. Liquid Ring

Air screw spinning in an eccentric Liquid ring arranged chamber forms the liquid ring

Key Applications

Bakery and Confectionery

  • Batters
  • Fats & Oils
  • Flavorings
  • Sweeteners
  • Yeast Slurry
  • Syrups




  • Whey
  • Cream
  • Milk
  • Sweetended Condensed
  • RO/UF Systems




  • Emulsions
  • Extracts
  • Slurries
  • Syrups
  • Dyes
  • Alcohols
  • Essential Oils




  • Detergents
  • Dyes
  • Soap Liquors & Solutions
  • Ammonium Nitrate
  • Propyl Alcohol
  • Potassium Chloride
  • Sodium Acetate



Inlet Size

Oulet Size

Max. Impeller
Max. Cap. (M3/H)
2900 RPM
Max. Head (MWC*)
2900 RPM
Max. Discharge Pressure (bar) Max. Operating
20/15 65 51 142 30 27 6


> 95°C, please contact SPX FLOW

30/30 65 51 175 50 40 8
44/50 76 51 220 90 65 13

* 10 mwc equals 1 bar

Ws+ pumps meet the requirements of the Regulation (EC) No 1935/2004 on materials and articles intended to come into contact with food and repealing Directives 80/590/EEC and 89/109/EEC.


Materials Port Connections Motor
Casing SS 316L Pumps can be supplied with all standard threads an d clamps in accordance to DS, BS, DIN, SMS and ISO as we ll as DIN flanges. IEC metric standard, at 50/60 Hz, IP55, insulation class F.
Ws+ pumps are as standard in Europe delivered with motors meeting the IE2 efficiency level in accordance to the Directive 2005/32/ EC Eco-design of Energy using Products.
Front Cover SS 316L
Impeller SS 316L
Air Screw and Recirculation Pipe SS 316L
Back Plate SS 316L
Shaft SS 316L
Clamp Rings SS 304
Extension Frame SS 304
Legs SS 304
Motor Shroud SS 304
Shaft Seal

Carbon/Silicon Carbide

Optional: Silicon Carbide/Silicon Carbide


EPDM (FDA Compliant)

Optional: FPM (FDA Compliant)


The Ws+ range consists of 3 basic models – Ws+20/15, Ws+30/30 and Ws+44/50 - with pressure and flow capacities to 6,5 bar (50 Hz) and to 90 m3/h (50 Hz). The use of a conventional open impeller design ensures a flexible flow range enabling adjustment of performance to application. A Ws+ pump can be optimized the same way as a conventional end-suction centrifugal pump.