Stopcock

Source: Wikipedia, the free encyclopedia.
See also: Petcock
Not to be confused with Cockblock.
Example of symbol for a stop valve.

A stopcock is a form of valve used to control the flow of a liquid or gas. The term is not precise and is applied to many different types of valve. The only consistent attribute is that the valve is designed to completely stop the flow when closed fully.

Use

Water service

Stopcocks are used to grossly regulate the flow of

tap water in residential and commercial services. One is found at the junction of a water main and the branch leading to an individual service (allowing the service to be isolated from the main trunk), and a second inside the structure (allowing its plumbing to be isolated from the branch line leading into it). Either is employed when maintenance or emergency repairs are conducted.[1]

Medical

Stopcocks are often used in medicine as a component of apparatus used in procedures such as intracranial pressure monitoring and other solution delivery procedures where varying amounts of liquid must be released without direct use of a syringe.[2]

Laboratory

A single hole hollow glass stopcock held in place by vacuum

For

Teflon. One can also find valves with Teflon spindle (for example one way valves or angled valves) When the plug is made of glass, the handle and plug are fused together in one piece out of glass. When both valve body and plug are made of glass, a suitable grease (e.g. silicone grease or Ramsay grease) is usually used to give a good seal, as well as to prevent the valve from seizing and subsequently cracking.[3]

Special stopcocks are available, such as a double-oblique or three-way design used in Schlenk lines which permit the application of inert gas and vacuum from the same stopcock.[4]

Stopcocks are often parts of laboratory glassware such as

PTFE. The ground glass stopcocks are greased to create an airtight seal and prevent the glass from fusing. The plastic stopcocks are at most lightly oiled.[3]

Stopcocks are generally available individually with some length of glass tubing at the ports so that they can be joined by a glass blower into custom apparatus at the point of use. This is especially common for the large glass manifolds used in high vacuum lines. Many additional variations exist in both plug boring and joint assembly. Stopcocks have been manufactured for laboratory use since at least the start of the 20th century.[5]

Types of laboratory stopcocks

  • 1-, 2- and 3-way stopcocks
  • Needle valve stopcocks straight or right-angled
  • Burette stopcocks straight or lateral
  • Desiccator stopcocks
  • Vacuum stopcocks one-way straight or parallel, one-way right-angled or 2-way

Gallery

  • A straight bore plastic stopcock without the female joint. Note its washer and nut system for attaching to its female joint.
    A straight bore plastic stopcock without the female joint. Note its washer and nut system for attaching to its female joint.
  • A T-bore glass stopcock in a three way assembly. Two of the outlets end in plain hose adapters while the third ends in a male 14/20 ground glass joint. This stopcock is attached with an easily removed metal spring.
    A T-bore glass stopcock in a three way assembly. Two of the outlets end in plain hose adapters while the third ends in a male 14/20 ground glass joint. This stopcock is attached with an easily removed metal spring.
  • A double oblique bore glass three-way stopcock
    A double oblique bore glass three-way stopcock
  • A stopcock in the open position, connected to the oil bubbler via a short hose
    A stopcock in the open position, connected to the
    oil bubbler
    via a short hose
  • A stopcock on a steam engine
    A stopcock on a steam engine
  • A cast-iron City of Birmingham stopcock cover, on the boundary of a residential property, from the time when the City Council was responsible for the supply of drinking water.
    A cast-iron City of Birmingham stopcock cover, on the boundary of a residential property, from the time when the City Council was responsible for the supply of drinking water.

References

  1. ^ Horsman, Paul (March 6, 2020). "What's a stopcock and what does it do?". Direct Line.
  2. ISBN 978-1-9751-2083-2
    .
  3. ^
    ISBN 978-1-4200-5670-9
    .
  4. ISBN 978-0-471-86773-9
    .
  5. ^ Office, Canada Patent (1911). Scientific Canadian Mechanics' Magazine and Patent Office Record. p. 961.

External links

  • Media related to Stopcocks at Wikimedia Commons
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