Extract of Basic Industrial Valves – Actuation System

An actuator is a device that allows the operation of a valve (open/close/set). All valves function under the operating conditions proper to a process. It is important that the actuation is adequately sized and adapted to the environment in which it will be used (size constraints, energy available on site, etc.).

The sizing of an actuator must primarily take into account the forces required to:

  • Ensure the sealing contact pressure for tight shut-off of the valve
  • Overcome frictional forces of the gland packing
  • Overcome the pressure difference between upstream and downstream of the valve (ΔP)

1/ Manual actuation

Extract of the Basics of industrial valves – material used in our training program.

A manually operated valve is equipped with a hand wheel or a crank lever. For quarter turn valves, (see “Technology” chapter), a lever allows the device to be operated quickly. Multi-turn operated valves are equipped with a hand wheel, or a crank handle that allows them to be operated faster. Among the multi-turn manual actuation mechanisms, two types of systems can be distinguished :

  • The “Turning, non-rising” system : while turning the hand wheel, a threaded nut (yoke nut/ adjusting nut) drives the actuation stem thread. The hand wheel is fixed and the stem is rising through the center of the hand wheel.
  • The “Rising hand wheel” system : the hand wheel is fixed on the actuation stem, acting directly on it. During operation, the stem turns at the same time as the hand wheel. The hand wheel moves linearly with the stem.

Manual actuation is adapted to equipment that is easily accessible and operated infrequently. This system is inexpensive, but requires the intervention of an operator. As an option, emergency hand wheels can be installe to override the motor controls, allowing operation of the valve in case of failure of the main actuator or of the power supply to the actuator.

basic of industrial valves actuation system guichon valves

Options :

  • Bevel gear
  • Offset hand wheel
  • Gear reducer (multiplication of forces, suitable for high operating torques)
  • Hand wheel locking system (cover, lock, padlock, chain, etc.)
  • Extension to control from a distance
  • Dead man handle (valve close automatically without intervention of operator)
  • Chain wheels (fit for valves high up or difficult to access)
  • ISO base for future adaptation of motorization

Read the full chapter – Basics of Industrial Valves “Actuation”