Igniter/Squib Circuit Testers

Munition Ignition Testing

Aerospace, defense, and commercial industry produce explosive devices, such as explosive squibs or ignitors, for various military and civilian applications. Considering first and foremost the military sector and further considering the intended purpose of such high energy explosives, both the inherent danger presented during the handling of weapons, and the critical nature of the deployed weapon’s reliability, are obvious yet bear repeating. There are secondary areas that use smaller explosive devices such as the guidance/deployment of those same weapons, and then there are tertiary uses (deploying countermeasures, ejection seats, etc). On the civilian side, airbag deployment in automobiles is accomplished through chemical explosive means. No matter what the size of the devices involved, they all are generally considered mission-critical, and despite the inherent dangers are used because they are powerful, fast-acting, and reliable.

Methods of Detonation

In most applications, the principal method of initiating the detonation is through electrical means, using a carefully designed ignitor circuit to safely trigger the explosive squib or similar device. Heat generated by the current flow provides the threshold energy needed to initiate events. Electro/mechanical trigger circuitry controls when the current gets applied. The small explosive often triggers a much larger explosive. The circuits are of varying complexity ranging from the simple low component count mechanisms found on “dumb bombs” to highly complex circuitry found in modern battlefield smart bombs or in automotive safety applications.

Safety & Reliability Evaluation Methods

Manufacturers and end-users alike have long sought methods to ensure safety and reliability of these devices. One such means is to electrically test the detonators, wire cabling, and control circuitry at various points in the life cycle, including:

QA tests during manufacturing of the raw components
QA tests during final assembly e.g. packing and loading
Integrity checks during and after storage in warehouses or depots
Point-of-use testing before deployment

It is critical to recognize that the method of testing applies electrical current to the device in a similar fashion to that which initiates detonation. The only way to safely accomplish the test is to severely limit the test current to a level several hundred to a thousand times lower than the detonation threshold.

Safety and Reliability Testing

The current-limiting circuitry must have high safety redundancy with known failure modes, that always fail to a safe condition. Furthermore, in many cases, the required accuracy of measurement is quite high often approaching a hundredth of an ohm. Under normal circumstances measuring resistance to that accuracy is difficult. However, the use of the necessarily low test currents exacerbates the difficulty as a direct ratio. To put it simply, lowering the test current by a factor of one thousand increases the difficulty of the measurement by a factor of one thousand.

Designing for Safety

The ability and experience to design such failsafe and accurate testers is where Raptor Scientific comes in.

Space Electronics Solutions

Space Electronics is a designer and manufacturer of igniter circuit testers approved by the US Department of Defense for failsafe measurement of the resistance and stray voltage in the multiple electrical circuit paths leading to critical components, like explosives, missiles, or rocket ignition. Our igniter testers come in single-channel and multi-channel models for testing simple electronics paths to complex multi-path circuits.

What Types of Devices are Tested? The Nomenclature...

Igniters or Ignitors - used to launch rockets and sometimes used to describe all other triggering methods
Fuzes (or less commonly fuses) used to trigger high energy (HE) explosives in bombs or submunitions
Mines - Antipersonnel, Antitank, or Anti-armor
Squibs - another highly interchangeable term, commonly
- Deploy parachutes
- Deploy countermeasures
- Eject canopies
- Fire Ejection Seats
- Deploy fins
- Pierce seals on automatic fire extinguishing liquids
- Initiate airbags for automotive use
Detonators - defined as demolition trigger devices or alternatively defined as bomb fusing devices
Initiators - yet another interchangeable term
Explosive bolts for launching missiles, blowing hatches, canister lids, etc. - sometimes interchangeable with "squibs"
Deployment mechanisms for countermeasures
Types of Electro Explosive Devices (EE)
- bridgewire (BW)
- film bridge (FB)
- conducting composition (CC)
- semiconductor bridge (SCB)
- exploding bridgewire (EBW)
- exploding foil initiator (EFI)
S&A - Safety and Arming devices and circuits
Wiring and cabling associated with all above devices

Squib Testing FAQs

What is a squib device?
A squib is an electroexplosive device (EED) containing a pyrotechnic charge that's initiated by electrical current. Squibs are used in aerospace (rocket stage separation), automotive (airbag deployment), military (ordnance igniters), and industrial applications requiring controlled explosive actuation.
What is a squib circuit?
A squib circuit is the electrical pathway from the firing control unit to the electroexplosive device. The circuit includes the power source, firing switch, wiring, connectors, and the squib's bridgewire or resistive element. Proper circuit testing ensures reliable initiation when required.
What is an igniter tester?
An igniter tester (also called squib tester or EED tester) is specialized equipment that safely measures the electrical characteristics of electroexplosive devices including resistance, continuity, and insulation resistance using sub-initiation currents.
What is the difference between a squib and a detonator?
Squibs and detonators are both electroexplosive devices, but squibs typically produce lower-energy output for mechanical actuation (like cutting bolts or deploying airbags), while detonators produce higher-energy output designed to initiate larger explosive charges. Both require specialized circuit testing.
How do igniter circuit testers ensure safety in defense systems?
Igniter and squib circuit testers verify the integrity and safety of electrical circuits used in defense systems before deployment or use. These devices can test current-limiting circuits, detect faults that could cause accidental ignition, and verify proper circuit operation under controlled conditions. By catching defects before systems are activated, circuit testers prevent dangerous misfire scenarios in missile systems, ammunition, and other weapons where accidental ignition could be catastrophic.
What are the main safety concerns in igniter circuit testing?
The primary concern is preventing accidental ignition while testing—a properly designed circuit tester uses limited current and voltage to verify circuit function without actually firing the igniter or squib. Other concerns include detecting short circuits, open circuits, insulation faults, and verifying proper resistance values. Circuit testers must be sophisticated enough to identify these faults while remaining safe for operators. Raptor Scientific's igniter circuit testers are engineered specifically for these safety-critical requirements.
What certifications and standards apply to igniter testing?
Igniter and squib testing is governed by military specifications and defense contractor standards, with requirements varying by application and country of origin. These standards define test procedures, safety protocols, and acceptable fault detection criteria. Raptor Scientific's testing equipment is designed to meet military specifications and support compliance with applicable defense standards.
How do current-limiting circuits protect against accidental ignition?
Current-limiting circuits restrict the electrical current flowing to an igniter or squib to safe levels—insufficient to actually fire the device. This allows technicians to test circuit continuity and function without the risk of accidental ignition. A properly designed igniter circuit tester will verify that current-limiting protection is working correctly and that the circuit can be safely tested without hazard.