Pyrotechnic Actuators

Piston Actuators

A pyrotechnic actuator (or explosive piston actuator) helps you achieve your mission-critical goal through an active stroke of an internal rod or piston to induce or control the desired motion. As an innovator in the motion control sector, we have led application advancement to initiate devices by any number of methods. Ordnance actuated Piston Actuators are designed to perform a multitude of work:

  • Pierce a pressurized vessel to release gasses
  • Remove shear nipples to again release pressurized gasses
  • Push mechanical features from point A to point B

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HOW IT WORKS

The rate of a desired push can be within a few milliseconds, to much longer times, depending on the need. The pistons can be designed to lock out once fired or be allowed to bounce back after performing the work. A Piston Actuator retains all explosive hot gasses with the use of various elastomeric seals. An electric piston actuator can be actuated by an electrical explosive device, however pyrotechnic actuators may also be actuated with a pressure cartridge, mechanical primer initiated device (gas generator), linear detonation transfer line (SMDC, FCDC, ETL, RDC) or a laser actuated ordnance device (laser initiated squib or detonator).

The gas energy from any of these devices expands rapidly in a confined space resulting in a volume change which drives the piston inside the actuator outwardly. Extension length of the piston is controlled by the envelope of the body and work needing to be performed. The pins extract rapidly in most applications creating a mechanical shock when the piston reaches full stroke. Dampeners can be installed into the Piston Actuators when lower mechanical shock is needed. In many applications, the shock of other devices being released is as great as or greater than that generated by Piston Actuator actuation.

Pyrotechnic thrusters are another form of a pyrotechnic piston actuator. They are often not called a piston actuator or pin pusher because they generally perform a more controlled amount of work. The end of the piston is usually attached to the system requiring movement from point A to B. The rate of movement and measured force of the movement is controlled as to not actuate with too much or too little energy. The timing of the piston movement can be controlled as needed for these thrusters.

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FUNCTIONS/APPLICATIONS

Functions

Pyrotechnic Actuators have almost unlimited applications for one-shot type devices such as:

  • Fire suppression
  • Landing gear emergency blow down systems
  • Missile guidance seeker coolant release
  • Missile canister cover removal
  • Door release on helicopters and space capsules
  • Fin and wing release
  • Satellite release systems
  • Missile release
  • Aircraft egress systems
Applications

Our Piston Actuators have been used in commercial aircraft egress systems, military escape systems, multiple missile platforms, military torpedoes, guided bombs and other weapons platforms. They were also used on the Space Shuttle.

PERFORMANCE SPECIFICATIONS

  • All-Fire
    Within 20 milliseconds @ 3.5 amp (when electrically initiated)
    Within 10 milliseconds from ETL input stimulus
  • No-Fire
    5 Minutes @ 1amp/1watt (when electrically initiated)
  • Operating Temperature
    -90 °F to +220 °F
  • Piston Travel Distance
    .15 to 2.50 inches typical
  • Side Loads
    100 – 1,700 lbs. force typical

Applicable Specifications

  • Qualified to MIL-DTL-23659
    (applies to electrical initiated Piston Actuator types)
  • MIL-HDBK-83578 Criteria for Explosive Systems used on Space Vehicles
    (design margin validation)
  • Compliant with MIL-STD-1901A
    (apples to energy transfer line initiated Piston Actuator designs)
  • MIL-STD-1576 Electro-Explosive Subsystem Safety Requirements and Test Methods for Space Systems
  • MIL-STD-1540 Test Requirements for Launch, Upper Stage and Space Vehicles
  • MIL-STD-202 Test Methods for Electron and Electrical Component Parts
  • MIL-STD-810 Environmental Engineering Considerations and Laboratory Tests

ENVELOPE/INTERFACE DESIGN

Pyrotechnic Actuators | Pin Pushers | Piston Actuators | Thrusters can all be customized to fit many customer envelopes.

This is a representation of our telescoping actuator. The amount of stroke for solid piston design is limited to this envelope. In an electrical linear actuated design, approximately .25” is needed for ordnance initiation. The balance of length can be reserved for the piston travel. With a side actuation (non-linear actuation), more linear envelope can be preserved for piston travel. Lengths less than 1 inch are produced but stroke on such designs are limited to around .15 inches.

At times, more stroke is needed than the envelope will allow for a solid piston design. In those instances, a telescoping style piston actuation can be designed. The following telescoping piston actuator has been in production at PacSci EMC for over 30 years and represents our largest piston actuator. The piston extension on this device is 6 feet from a start of approximately 1 foot.

Telescoping Piston Actuator Extended