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The 7 key functions of diaphragms

For each diaphragm project developed, EFFBE’s engineers and technicians take scrupulous care to optimise the key functions of the diaphragms, which are divided into 7 major families.

The geometry of the diaphragm and the choice of reinforcement and elastomer are determined by iterative calculation, and all dimensions and realistic tolerances are offered by EFFBE to its customers.

Frequently, along with suggesting the diaphragm type and its specified dimensions, EFFBE co-develops with the customer and proposes the definitions of the surrounding parts. The aim is to comply in every respect with the test protocols defined by our customers.

These elements depend on the input data in the functional specifications:

  • Pressure differences
  • Extreme temperatures
  • Frequencies and harmonics
  • Service life, number of cycles
  • Geometry and volume available
  • The types of surrounding materials and how they are obtained
  • Maximum stroke required
  • Products in contact

Control function

The aim is to transform a pressure difference into force.

The diaphragm is pressurised or depressurised hydraulically or pneumatically on one side and transforms the differential pressure into a pulling or pushing force directed in one direction only with a displacement (stroke limited by a stop). The movement can be reversed either by a return spring when the pressure is released, or by an alternating pressure movement. The force created drives a mechanism.


  • Valve control
  • Servo brakes
  • Valve drive
  • Distribution elements
  • Servomotor
  • Pressure/vacuum caps
  • Turbocharger turbine supply valve actuators
EFFBE diaphragm control function, solar panel orientation, nuclear industry actuator

Regulation function

The aim is to transform a pressure difference into force, but with a regulation function around a set point.

The diaphragm, together with a stressed spring, is mechanically connected to a device for opening and closing a passage, which remains open as long as the pressure-dependent force transmitted by the diaphragm does not exceed the force of the spring. The passageway closes as soon as the force transmitted by the diaphragm exceeds that of the spring and activates the closing device by its movement. The drop in pressure resulting from the flow of product causes the spring to return, resulting in a new movement of the diaphragm to reopen the passage.


  • Pressure regulators
  • Pressure reducer
  • Flow regulators
EFFBE diaphragm control function, H2 storage, H2 compressor, refrigerant valves , cooling valves, coolant valves

Pump function

The aim is to transform a driving force into a mechanical force.

The diaphragm, activated mechanically (or electromagnetically) with or against the return spring, causes, depending on the direction of its stroke, alternately either an enlargement (suction movement) or a reduction (expulsion movement) of the volume it delimits. Valves in the suction and discharge openings ensure that the conveyed product flows in the same direction. The operating frequency and volume define the flow rate, driving force or return spring force, which in turn define the discharge pressure for given dimensions.


  • Fuel pumps
  • Return pumps (carburettor)
  • Vacuum pumps
  • Dosing pump
  • Mixing pumps
  • Compressors
EFFBE diaphragm pump function, heavy chemical industry, vacuum pumps for drones, pump for CO2 capture, CO2 storage, mobile respirators

Valve function

The aim is to release a gas or fluid as soon as the pressure exceeds a defined threshold.

A spring-loaded diaphragm holds the sealing seat of a valve in the closed position to prevent leakage. The passage remains closed as long as the force transmitted by the diaphragm and dependent on the pressure of the medium does not exceed the force of the spring. As soon as the force transmitted by the diaphragm is greater than the force of the spring, the diaphragm moves against the spring, opening the valve seat and allowing the product to pass through.


  • Pressure relief valve
  • Safety valve
EFFBE diaphragm valve function, vertical closing

Accumulator function

In this application the function of the diaphragm is to separate products with pressure balance.

Spherical or other accumulators are made up of two hemispherical caps assembled by screwing and clamping a diaphragm. The diaphragm is fitted with a metal stop which seals the operating orifice when the fluid has been completely drained, thus avoiding any risk of damage to the diaphragm. The orifice on the gas side is fitted with an inflation valve to control the nitrogen pressure in the accumulator.


  • Expansion vessel volume compensator
  • Hydraulic accumulators
  • Oleopneumatic suspension 
  • Pressure dampers
EFFBE diaphragm accumulator function, dual clutch transmission diaphragm

Damping suspension function

These diaphragms reduce pulsation and vibration during pump operation, ensuring a continuous, non-pulsating flow with reduced vibration and noise in the system piping.


  • Oleopneumatic suspension
  • Air suspension
  • Pulsation dampers
EFFBE diaphragm suspension function, fuel circuit, pulsation dampers

Flexible sealing function

The aim is to ensure a seal between 2 chambers so that the fluid in chamber 1 does not pass into chamber 2 and vice versa.

The diaphragm is used in place of a piston with a sliding seal in a cylinder and offers a multitude of advantages:

  • No friction
  • No lubrication required
  • No stick slip effect
  • Long service life
  • No effort to move
  • Low hysteresis
  • Multidirectional


  • Sealing diaphragms for electro-actuators
  • Cardan shaft bellows
  • Actuator bellows
  • Abrasive dust-limiting separation diaphragms for mechanical engineering 
  • Dynamic protection diaphragms for peristaltic pumps
  • Flexible protection in medical imaging
  • Heat shields for rocket boosters
  • Flexible barriers to electromagnetic waves
  • Flexible electromagnetic wave absorbers 
  • Flexible photon barriers (X and gamma)
  • UV flame barriers
  • Flexible ballistic protection
  • Ultrasonic ampoules for lithotripters
  • Diaphragms for ultrasound probes