Ordnance Safe and Arm (OSA) Devices | Interrupter | PacSci EMC
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Ordnance Safe and Arm (OSA) Devices | Interrupter.

Electro-mechanical Safe and Arm | Interrupter

PacSci EMC / Products / Safe and Arm Devices / Ordnance Safe and Arm (OSA) Devices | Interrupter


Ordnance Safe and Arm

The Ordnance Safe and Arm Device (OSA) or Interrupter Device is an electro-mechanical safe & arm device used to initiate an explosive train once it is in the ARM state. The interrupter device also provides intrinsic safety against inadvertent initiation of the explosive train when it is in the SAFE state. The Interrupter utilizes a booster to provide the necessary output to initiate various ordnance devices in a continuing explosive train, such as an FCDC. When the Interrupter is in the SAFE position, the booster is mechanically isolated from the explosive train outputs providing a barrier to prevent accidental explosive train initiation. When the interrupter is in the ARM position, the booster is moved in-line with the explosive train input and output ports, providing the correct state to facilitate explosive train initiation. The interrupter booster is initiated by an energetic input stimulus at the interrupter input port from FCDC, DBA, or other types of Initiator, than an electrical input. An electrical stimulus is used to place the interrupter in the ARM or SAFE position. The Interrupter contains both local visual (window) and remote electrical redundant SAFE and ARM position monitor circuits. In addition the Interrupter includes a safing mechanism for manual safing.

The OSA, or electro-mechanical safe and arm device, is used to initiate explosive trains where intrinsic safety against in-advertent initiation of the explosive train is demanded. Applications include rocket or missile assembly and deployment, especially where solid rocket motors are involved.

The PacSci EMC interrupter design is qualified and extensively used on solid rocket motor missile and rocket systems, including Atlas and Delta rockets.

All-Fire Angle
All-Fire angle for .999 reliability and 95% confidence = 81.2° from full safe

No-Fire Angle
No-Fire angle for .999 reliability and 95% confidence = 43.9° from full arm

Input Stimulus
FCDC, DBA or similar

Operating Temperature
-54°C to +74°C

Arming/Safing Voltage
22 to 35 VDC

Qualified to MIL-DTL-2365

Insulation Resistance
22 to 35 VDC

Electrostatic Discharge Immunity
Booster is immune to ESD pulses applied to the interrupter

Pre-function Leak Specification
5 x 10-5 standard cc/second of Helium

Applicable Specifications
Meets requirements of MIL-STD-1576 and MIL-STD-454
Meets requirements of MIL-STD-464 (EMI)


Geometric and electrical interface features are customizable to meet your applications.

Ordnance Safe and Arm Technical Envelope



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