Air Operated Double Diaphragm Pumps

DF50 Metallic and Non Metallic Air Operated Double Diaphragm Pumps

Air Operated Double Diaphragm Pumps

Superior All-Round Pumping Performance
Significant dry suction lift eliminates self-priming issues
Discharge fluids at up to 7 bar (100 psi), to pump even medium viscosity fluids over long pipe runs and up to significant heights
Efficient compressed air usage

Simple, Reliable & Durable
Few parts
Start up every time
Easy operation, for example: variable flow rate and pressure by adjusting the air pressure
Inline servicing possible without disconnecting the fluid lines
Quick error free non-expert maintenance
Short stroke and robust construction long life diaphragms

Compact design
No protuding manifolds
Integrated muffler
Metal fluid connections and external parts for noncorrosive applications
Tough plastic external parts for corrosive applications

Smooth Running
Gentle pumping suitable for fluids that may form emulsions or shear sensitive fluids
Reduced pulsation: greater accuracy during dosing and less splashing when dispensing
Fewer vibrations and lower noise level

Ai1r Operated Diaphragm Pumps1Innovative Samoa Technologies Inside

Conventional air operated diaphragm pumps pump the fluid around the outside of the pump and compressed air acts on the inside face of the diaphragms. Directflo pumps are inside out pumps, the fluid is pumped through the centre of the pump and compressed air acts on the outside face of the diaphragms.

Important innovations were necessary to realise the central flow concept and, whilst developing Directflo, further inventions were made that built on the central flow concept. A few highlights are described below.

A – Frictionless Pivoting Air Valve

  • High operational reliability
  • Variable flow rate and pressure by adjusting the air pressure
  • Non stalling
  • Non icing
  • Self-cleaning
  • Extremely fast switching between strokes reduces air consumption and minimizes pulsations
  • Enables a short stroke pump design, for long diaphragm life
  • Tolerates dry, damp, dirty or oily air

 B – Ball Check Valves Adjacent To Diaphragms

  • Very fast valve action, even with viscous fluids. Together with the high speed frictionless pivoting air valve, this enables a short stroke pump design, for long diaphragm life
  • Enables superior pump suction and thus improves overall pump performance

C – Stress Free Diaphragm Couplings

  • Non-rigid sliding couplings between push rod and diaphragms prevent diaphragm and push rod stress
  • Long leak free diaphragm life
  • Fast and easy diaphragm service

D – Single Part Moulded Pump Body

  • Minimizes energy losses within the pump
  • No leaks
  • Compact

E – Flange Fastening Plates

  • Pumps with plastic central bodies are fitted with load spreading stainless steel flange fastening plates
  • Reduces the risk of damage to plastic bodies when flange bolts are over tightened
  • Enhances sealing in the areas between flange bolts and so reduces the risk of flange leaks


Directflo® pumps are also available without the directional air valve and without the end of stroke sensors, to be externally driven. These special pumps are used, for example, in dosing applications.

Wide Choice Of Materials




Directflo® PUMP RANGE

Plastic Directflo® pump wetted bodies are compatible with even the most aggressive chemicals, and the plastic directional air valve and air chamber covers are suitable for use in corrosive environments.



Metal Directflo® pumps are extremely robust and thanks to a wide range of wetted materials are compatible with many fluids.