A pyrotechnic valve, also explosive actuated valve, short pyro valve or pyrovalve is a one time use

propulsion Propulsion is the generation of force by any combination of pushing or pulling to modify the translational motion of an object, which is typically a rigid body (or an articulated rigid body) but may also concern a fluid. The term is derived from ...

component often used to control

propellant A propellant (or propellent) is a mass that is expelled or expanded in such a way as to create a thrust or another motive force in accordance with Newton's third law of motion, and "propel" a vehicle, projectile, or fluid payload. In vehicle ...

or pressurant systems aboard

spacecraft A spacecraft is a vehicle that is designed spaceflight, to fly and operate in outer space. Spacecraft are used for a variety of purposes, including Telecommunications, communications, Earth observation satellite, Earth observation, Weather s ...

space probe Uncrewed spacecraft or robotic spacecraft are spacecraft without people on board. Uncrewed spacecraft may have varying levels of autonomy from human input, such as remote control, or remote guidance. They may also be autonomous, in which th ...

s. The device is activated by an electric signal, upon which one or several small

explosive charge An explosive (or explosive material) is a reactive substance that contains a great amount of potential energy that can produce an explosion if released suddenly, usually accompanied by the production of light, heat, sound, and pressure. An exp ...

s are ignited. These in turn produce high-pressure gas which either push a small, perforated

piston A piston is a component of reciprocating engines, reciprocating pumps, gas compressors, hydraulic cylinders and pneumatic cylinders, among other similar mechanisms. It is the moving component that is contained by a cylinder (engine), cylinder a ...

which initially blocked the flow path of the working fluid forward until the hole aligns with the tubing, allowing the working fluid to flow, or force a sharpened

through a weakened part of the attached tube to block the flow path of the working fluid. These two versions of pyrotechnic valves are referred to as normally-closed (NC) or normally-open (NO) valves respectively, depending on their initial state before initiation of the pyrotechnic charge. Modern pyrotechnic valves feature two

redundant Redundancy or redundant may refer to: Language * Redundancy (linguistics), information that is expressed more than once Engineering and computer science * Data redundancy, database systems which have a field that is repeated in two or more table ...

s in order to maximize reliability of the valve. There are several advantages of pyrotechnic valves over other types of

valves A valve is a device or natural object that regulates, directs or controls the flow of a fluid (gases, liquids, fluidized solids, or slurries) by opening, closing, or partially obstructing various passageways. Valves are technically fittings, ...

, such as

solenoid valve A solenoid valve is an electromechanically operated valve. Solenoid valves differ in the characteristics of the electric current they use, the strength of the magnetic field they generate, the mechanism they use to regulate the fluid, and the ...

s: * Pyrotechnic valves have an extremely fast response time (time from the actuation signal reaching the device til the valve has closed/opened), often in the order of a few

milliseconds A millisecond (from '' milli-'' and second; symbol: ms) is a unit of time in the International System of Units equal to one thousandth (0.001 or 10−3 or 1/1000) of a second or 1000 microseconds. A millisecond is to one second, as one second i ...

. * Normally-closed pyro valves have a far lower leak rate than other valves, allowing them to hermetically seal propellant inside a tank to keep it from

evaporating Evaporation is a type of vaporization that occurs on the surface of a liquid as it changes into the gas phase. A high concentration of the evaporating substance in the surrounding gas significantly slows down evaporation, such as when humi ...

into

space Space is a three-dimensional continuum containing positions and directions. In classical physics, physical space is often conceived in three linear dimensions. Modern physicists usually consider it, with time, to be part of a boundless ...

before activation. This is especially useful on

which spend

years A year is a unit of time based on how long it takes the Earth to orbit the Sun. In scientific use, the tropical year (approximately 365 solar days, 5 hours, 48 minutes, 45 seconds) and the sidereal year (about 20 minutes longer) are more exa ...

decade A decade (from , , ) is a period of 10 years. Decades may describe any 10-year period, such as those of a person's life, or refer to specific groupings of calendar years. Usage Any period of ten years is a "decade". For example, the statement ...

s coasting through

before reaching their destination. If propellant is needed only every few years or so, NO pyro valves and NC pyro valves can be arranged in pairs, breaking the seal when required, then sealing it again afterwards. This type of system is being referred to as a pyro ladder.

Examples

* Eight pyrovalves controlled the descent of the

Perseverance Perseverance most commonly refers to: * ''Perseverance'' (rover), a planetary rover landed on Mars by NASA * Psychological resilience Perseverance may also refer to: Geography * Perseverance, Queensland, a locality in Australia * Perseverance I ...

Mars rover A Mars rover is a remote-controlled motor vehicle designed to travel on the surface of Mars. Rovers have several advantages over stationary landers: they examine more territory, they can be directed to interesting features, they can place them ...

after seven months of flight. *

References

{{reflist

External links

Dassault Aviation: Pyrotechnic valve ''(Archived)''

Pyrotechnics Spacecraft pyrotechnics Valves