A non return valve is a motorized gadget, a valve, which restricts flow of fluid, liquid, or gas, only in a particular direction. They have two openings, one through which the substance enters and one through which it leaves. These are known as the inlets and outlets of the valve. There are multiple such valves which are used for a variety of applications. Though they come in various shapes and sizes, these valves are generally very simple tools and are not very costly.
The non return valve has an automated mode and need no external manual or machine control. They are self operated. The materials used for making such valves are mostly metal and plastic. These valves operate based on the pressure requirements of fluids, liquids, or gasses. They are designed according to the pressure that will be required to be regulated depending on which substance is being dealt with.
There are several varieties in the category of the non return valve. A backwater valve is used for sanitary and drainage system. This helps to clog the backflow of sewage water into the rooms located below their level. The ball type check valves are ones that are used in sprays and dispensers. This type of valve works under pressure to emit the liquid or gas in a jet like manner. Prolonged usage sometimes can wear off the valve.
A diaphragm check valve uses a rubber diaphragm to regulate the pressure. With the release of pressure, the diaphragm is back in its original position. Swing check valves are those which are used in the flush of a toilet. The pressure from the tank holds it closed and manual lift of the flapper opens the valve and let go of the water into the toilet. Stop check valves are those used to control the flow regardless of the flows course or force. Apart from these there is the lift-check valve, duckbill valve, etc., which are again used for various purposes.
Check valves have different applications and are fitted for various purposes. The main utilization is in pumps, to check the flow of water and to avoid the back-flow of water due to rise or fall in water pressure. Industrially, these valves are used in power and chemical plants, especially when there is necessity to mix several gasses into a single gas flow. Domestically also these valves are very useful, especially in the spheres of irrigation and drip irrigation. These valves keep the lines from running dry even when the source is shut off. The snow makers that are used in parties and other entertainment programs have this kind of valves. Even the rainwater harvesting systems used for domestic purposes are fitted with these non return valves in order to check the contamination of the main supply by rainwater.
In our day to day life as well as on a large industrial scale, these valves play an important role in functioning of multiple devices. The pressure controlling efficacy of these valves result in the proper functioning of the devices in which they are fitted.