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 f ...

component often used to control propellant or pressurant systems aboard

spacecraft A spacecraft is a vehicle or machine designed to fly in outer space. A type of artificial satellite, spacecraft are used for a variety of purposes, including communications, Earth observation, meteorology, navigation, space colonization, p ...

space probe A space probe is an artificial satellite that travels through space to collect scientific data. A space probe may orbit Earth; approach the Moon; travel through interplanetary space; flyby, orbit, or land or fly on other planetary bodies; or ...

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 expl ...

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

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 fitting ...

, 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 ty ...

s: * Pyrotechnic valves have an extremely fast

response time Response time may refer to: *The time lag between an electronic input and the output signal which depends upon the value of passive components used. * Responsiveness, how quickly an interactive system responds to user input * Response time (biolog ...

(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 (SI) equal to one thousandth (0.001 or 10−3 or 1/1000) of a second and to 1000 microseconds. A unit of 10 milliseconds may be called ...

. * 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. High concentration of the evaporating substance in the surrounding gas significantly slows down evaporation, such as when humidi ...

into

space Space is the boundless three-dimensional extent in which objects and events have relative position and direction. In classical physics, physical space is often conceived in three linear dimensions, although modern physicists usually cons ...

before activation. This is especially useful on

which spend

years A year or annus is the orbital period of a planetary body, for example, the Earth, moving in its orbit around the Sun. Due to the Earth's axial tilt, the course of a year sees the passing of the seasons, marked by change in weather, the hou ...

decade A decade () is a period of ten years. Decades may describe any ten-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 that "du ...

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 may refer to: Behaviour * Psychological resilience * Perseverance of the saints, a Protestant Christian teaching * Assurance (theology) Geography * Perseverance, Queensland, a locality in Australia * Perseverance Island, Seychelles ...

Mars rover A Mars rover is a 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 themselves in sunny pos ...

after seven months of flight. *

References

{{reflist

External links

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

Pyrotechnics Spacecraft pyrotechnics Valves