Piston valve

For piston valves on steam locomotives, see Piston valve (steam engine).

File:Dugattyus szelep.png

Piston valve in a brass instrument

A 'piston valve' is a device used to control the motion of a fluid along a tube or pipe by means of the linear motion of a piston within a chamber or cylinder.

Examples of piston valves are:

• The valves used in many brass instruments
• The valves used in pneumatic cannons
• The valves used in many stationary steam engines and steam locomotives

Brass instruments

File:Trompette - premier piston - montage perspective.jpg

First piston valve of a B♭ trumpet

Cylindrical piston valves called Perinet valves (after their inventor, François Perinet), are used to change the length of tube in the playing of most brass instruments, particularly the trumpet-like members of the family (cornet, flugelhorn, saxhorn, etc.).

Other brass instruments use rotary valves. notably the orchestral horns and many tuba models, but also a number of rotary-valved variants of those brass instruments which more commonly employ piston valves.

The first piston-valved musical instruments were developed just after the start of the 19th century. The Stölzel valve (invented by Heinrich Stölzel in 1814) was an early variety. In the mid 19th century the Vienna valve was an improved design. However most professional musicians preferred rotary valves for quicker, more reliable action, until better designs of piston valves were mass manufactured in towards the end of the 19th century.

Pneumatic cannons

A piston valve can also refer to a 2-way 2-position, pilot-operated spool valve. The term is extremely popular among spud gun enthusiasts who often build homemade piston valves for use in pneumatic cannons. Valves are typically constructed primarily from pipe fittings and machined plastics or metals. The inside of a piston valve contains a piston that blocks the output when the valve is pressurized, and a volume of air behind the piston. When the pressure behind the piston is released the piston is pushed back by the force of the pressure from the input. This allows the valve to be opened by a much smaller pilot valve, with speeds faster than possible with just a manually operated valve. Functionally these types of valves are comparable to quick exhaust valves.

This type of piston valve is also sometimes referred to as a back-pressure valve.

Steam engines

Main article: Piston valve (steam engine)

See also

• Angle seat piston valve

External links

• Early valve designs
• Why was the valve invented?
• Elements of Brass Instrument Construction with good discussion of valve types and history
• Visual explanations of some types of piston valve
• Kinematic Models for Design Digital Library (KMODDL) – Movies and photos of hundreds of working mechanical-systems models at Cornell University. Also includes an e-book library of classic texts on mechanical design and engineering.
• 12px de:Ventil (Blasinstrument)