They are all around us and pass largely unnoticed. Fluids are anything that is liquid but, in this sense of the word, gases are also included. When fluid is in storage, it needs little control. Water sits in a lake and domestic propane gas needs to be kept inside cylinder.
However, for fluid application, movement will probably be required. For lake water to be available at the faucet on our kitchen sink, we have to pump it out of the lake and into a pipework system that feeds water through to our house. However, we do not want a free flowing river like torrent of water. The pump starts the water on its way but the flow will be controlled by stop/go devices known as valves. The final valve takes the form of the faucet on our sink.
Many Types Of Valve
Valve designs are many and varied as are the materials from which valves are made, they also come in many different sizes from minute up to being literally as large as a house. However, they all serve a single purpose and that is to control the flow of fluid that passes through them.
Some valves do nothing more than to stop fluid flow when the valve is closed or to allow flow when the valve is open. Other valves can also change the direction of the fluid flow while some are used to raise or lower the flow rate of the fluid. Valves can also be used to change the pressure on the fluid. A valves design is a result of the type of control it has to perform and its material of construction depends on the nature of the fluid passing through it.
Most valves are not all that much different in concept from the humble household faucet. Fluid can enter from a pipe connected to one side of the valve and a mechanism within the valve can be opened or closed by applying hand force to an arm or a wheel at the top of the valve. In the open position, the fluid flows out the other end of the valve.
A Diaphragm Valve
Valves like Authorized Parts McCanna Diaphragm Valves utilize a flexible diaphragm which in the open position allows fluid to flow through the valve. But when closed, the diaphragm is pushed against a shaped portion within the valve so as to close off all gaps and stop the fluid from flowing through. The diaphragm is usually made in a rubber material.