Safe and Arm Devices
50 Years of Experience
A Safe and Arm Device (SAD) prevents any main charge explosive (military, oil and gas, or space vehicles) from accidental initiation prior to arming, while at the same time allowing the intended explosive train to detonate once it has been armed. Basically a safe arm device controls the initiation of a pyrotechnic train such that the energetic output is fired only when commanded and is safe at all other times. It’s a device that prevents inadvertent arming or firing of a pyrotechnic event and makes the system is insensitive to environmental stimulus, such as fires, electro-magnetic fields, stray voltages and electro-static discharge
Our Safe and Arm Devices
- Arm Fire Device
- Electronic Safe & Arm Device
- Electronic Ignition Safety Device
- Electro-mechanical Safe & Arm Device
- Ordnance Safe & Arm Device
What are Safe and Arm Devices?
Simply stated, an in-line Safe and Arm Device (SAD) is a high voltage safe arm device. It consists of:
- Safety Input inhibit signals
- Safety logic circuity
- Pyrotechnic output, which can be either
- Deflagrating (burn and create heat and pressure)
- Detonating (produce shock output)
Because SADs can use either type of output, they can initiate a wide variety of pyrotechnic events. There are some options around deflagrating and detonating and also some overlap between the two. It’s possible to change from deflagrating to detonating or transfer vice versa.
Safe and arms can be used for rocket motor ignition to initiate cable cutters, separation nuts, or any kind of pressure actuated cartridge. They can also be used to start exploding transfer lines or fire into bulk destruct charges and expanding tubes, and this wide variety of pyrotechnic events is possible because of the different variety of outputs.
Most events don’t need a SAD, but there are four safety critical areas that drive our customers to need a Safe and Arm Device. If the requirement doesn’t fall into one of these four categories:
- Rocket Motor Ignition
- Hand Emplaced Ordnance/Vehicle Active Protection Systems
- Warhead Fuzing
- Flight Termination
An example not requiring a SAD would be the stage separation on a multi-stage vehicle. There are occasionally other fringe areas that could requires SADs.
A weapon or launch system that does require a safe and arm relating to the four areas is almost always going to include the involvement of one of the related safety groups which control these types of devices. Such as each weapons test range in the U.S., each with its own range safety group, which would approve the use of Flight Termination System (FTS) safe and arm device. Some additional examples are
- 30th space wing at Vandenberg Air Force Base
- 45th space wing for the eastern ranges
There are also dedicated groups based on technology, rather than location based groups mentioned above, which include:
- Ignitions System Safety Review Board (ISSRB) approve designs for Ignition Safety Devices (ISD) and other safe and arms
- Fuze and Initiation System Technical Review Panel (FISTRP)(ISD Fuzes)
- Weapon System Explosives Safety Review Board (WSESRB) (Munitions and Fuzes
- Army Fuze Safety Review Board (AFSRB)
- Air Force Nonnuclear Munitions Safety Board (NNMSB)
Each one of these panels controls a different device on a different platform in a different area. The devices we discuss here are relevant to these safety boards.
Let’s start with defining what a SAD is: A device whose purpose is to control the initiation of a pyrotechnic device such that the energetic output is fired only when commanded and is safe at all other times. It’s a device that prevents inadvertent arming or firing of a pyrotechnic event and makes the system is insensitive to environmental stimulus, such as
- Electro-magnetic fields
- Stray voltages
- Electro-static discharge
SADs are required any time there is a risk to personnel or infrastructure if a pyrotechnic sub-system were to malfunction. These requirements exist because of several key disasters in the past. One such example is the USS Forrestal aircraft carrier fire in 1967. A fire in which a rocket inadvertently launched, causing a fire which then ignited other munitions onboard. That disaster resulted in the deaths of 134 sailors and crippling of the ship. These older weapon systems at the time did not use safe and arms. Most used simple hot wire devices, squibs or bridgewires.
Today, PacSci EMC SADs exist in many systems including:
- Commercial and defense aircraft
- Commercial and defense launch vehicles
- Tactical and strategic missiles
- Variety of munitions
- Vehicle active protection systems
To learn more about design principles of safe arm device, view this article from the Naval Air Warfare Center.
100,000+ Safe and Arm Type Safety Devices of Various Configurations
- Over the past 3 decades we have supported over 48 program platforms
- Simultaneously fired
- Used in the Space Launch Vehicle for Flight Termination Systems (FTS), Solid Rocket Booster (SRB) ignition systems, ignition stage separation and 2nd stage engine ignition
- Used in Tactical and Strategic Missile Platforms for FTS
Our Missile control safety and arming product line is suitable for application in all weapon system types including missiles, bombs, sea mines, torpedoes and Explosive Ordnance Disposal Systems. Also, our SAD and AFD product line contains designs that are MIL-STD-1901A and RCC-319 compliant across the technologies that we offer. Our long history and experience is demonstrated from our collaborative working relationship with the multitude of government safety boards. Our reliable SAD and AFD product line includes the following technology basis.
Our SAD and AFD product lines contain designs that are MIL-STD-1901A and RCC-319 compliant across the technologies that we offer. Our long history and experience is demonstrated from our collaborative working relationship with the multitude of government safety boards.
What is a safe arm device?
A safe arm device is meant to prevent a main charge in an explosive train from inadvertently detonating while also allowing for detonation when the main charge is intended to detonate.