Editing Check valve (section)

===Ball check valve===
{{multiple image
| width     = 100
| footer    = A ball check valve in the open position to allow forward flow and closed position to block reverse flow
| image1    = checkvalveopen.svg
| alt1      = Forward through a hole pushes away a ball that was blocking the far side of the hole, allowing flow to occur. The motion of the ball compresses a spring.
| image2    = checkvalveclosed.svg
| alt2      = Backward flow pushes a ball against a hole, preventing outward flow through the hole. A spring expands to help hold the ball in place.
}}

A ball check valve is a check valve in which the closing member, the movable part to block the flow, is a ball. In some ball check valves, the ball is [[Spring (device)|spring]]-loaded to help keep it shut. For those designs without a spring, reverse flow is required to move the ball toward the seat and create a seal. The interior surface of the main seats of ball check valves are more or less conically tapered to guide the ball into the seat and form a positive seal when stopping reverse flow.

Ball check valves are often very small, simple, and cheap. They are commonly used in liquid or gel minipump dispenser spigots, spray devices, some rubber bulbs for pumping air, etc., manual air pumps and some other [[pump]]s, and refillable dispensing syringes. Although the balls are most often made of metal, they can be made of other materials; in some specialized cases out of highly durable or inert materials, such as [[sapphire]]. [[High-performance liquid chromatography]] [[pump]]s and similar high pressure applications commonly use small inlet and outlet ball check valves with balls of (artificial) [[ruby]] and seats made of sapphire<ref>{{Cite journal|url=http://www.chromatographyonline.com/how-does-it-work-part-1-pumps?pageID=1 |title=Chromatography on line, from J.W. Dolan, LCGC North Am. 26(6), 532–538 (2008).|journal=LCGC Europe |series=LCGC Europe-05-01-2016 |date=20 May 2016 |volume=29 |issue=5 |pages=258–261 |last1=Dolan |first1=John }}</ref> or both ball and seat of ruby,<ref>{{Cite web|url=http://www.industrialvalvestore.com/de/node/2 |title=Industrial valve store>>Valves>>Check Valves, paragraph on ball check valves}}</ref> for both hardness and chemical resistance. After prolonged use, such check valves can eventually wear out or the seat can develop a crack, requiring replacement. Therefore, such valves are made to be replaceable, sometimes placed in a small plastic body tightly fitted inside a metal [[compression fitting|fitting]] which can withstand high pressure and which is screwed into the pump head.{{Citation needed|date=August 2023}}

[[File:Brass-Spring-Check-Valve 82799-480x360 (4999932405).jpg|thumb|A disassembled poppet check valve]]
There are similar check valves where the disc is not a ball, but some other shape, such as a [[Poppet valve|poppet]] energized by a spring.  Ball check valves should not be confused with [[ball valve]]s, which are a different type of valve in which a ball rotating on a pin acts as a controllable rotor to stop or direct flow.