PVC Check Valve
PVC check valves are one type of many types of plastic check valves, which exist to control and ensure the proper flow of fluids through a system. Specifically, they make sure liquid, gas or slurry flows only in one direction and does not backflow. Sometimes, PVC check valves are also referred to as PVC clack valves, PVC non-return valves or PVC non-return valves. Either way, PVC check valves are made of the diverse thermoplastic polymer resin of the same name, PVC, less commonly referred to by its full name, polyvinyl chloride. PVC can be formulated in a number of different ways in order to make it better able handle to the various abrasive, acidic or corrosive materials that may flow through a check valve. PVC check valves serve flow applications of a variety of commercial, industrial and domestic processes.
Typically, PVC is produced through the suspension polymerization of vinyl chloride monomers and water. Often, other substances, such as plasticizers, stabilizers and lubricants, are added in to impart specific additional properties to the PVC. Additives can, for example, render the polymer transparent or opaque, conductive or insulating and/or flexible or rigid. After the PVC itself is synthesized, in order to transform it into check valves, manufacturers may choose from a variety of available processes. These include stamping, injection molding, extrusion and, occasionally, die molding. Most PVC check valves are constructed in basically the same way: They have an inlet port, an outlet port and a stopper mechanism. When fluid flows in through the inlet port, it puts forward-direction pressure on the valve. A properly functioning valve will then allow the stopper mechanism, most likely a disc, ball or piston, to displace slightly. It will only open in one direction and the pressure from a flow from the other side, rather than opening it, will create an airtight seal by pushing the stopper back into its hole. The valve will only open again when the forward pressure is greater than the back pressure. Because the workings of PVC check valves are entirely self-contained, requiring no external actuation or activation, incorporating them into an already existing cistern or pipe is very easy.
PVC is chosen as check valve material for a number of reasons. Some of these include the fact that it is smooth, flexible and nontoxic. Additionally, when used as the seal of plastic and metal valves alike, PVC compresses and creates a very tight and effective seal. What’s more, PVC can be fabricated into precise shapes with relative ease. PVC check valves exhibit many of the same characteristics as metal check valves, but with much lower overhead costs. Likewise, the production of PVC requires much less petroleum than most other plastics, making it more environmentally-friendly and, once again, more cost effective. Those considering PVC check valves should consider the PVC composite they choose carefully. Each one will display certain key behaviors and properties, such as pressure ratings, thermal capabilities and dimensions, differently.
Subtypes of PVC check valves include: PVC ball check valves, diaphragm check valves and swing check valves or tilting disc check valves, among others. Ball check valves are check valves that have a spherical ball for their closing member, or movable part that blocks the fluid flow. Some ball check valves are equipped with a spring loading mechanism, which helps hold the ball in place. For those ball check valves without this mechanism, the valve is kept shut by a reverse flow that keeps the ball at the seat and sealing it. Next, diaphragm check valves are normally closed valves that stay closed using a flexible rubber diaphragm. To work, it is essential that pressure on the upstream end be greater than pressure on the downstream end by an adequate pressure differential, or certain amount. When the pressure is high, the valve opens, and when it is low, it closes. Swing check valves are check valves that have a disc that swings on a trunnion or hinge. The disc, or movable part that blocks flow, either swings off the seat to permit forward flow or swings onto the seat to obstruct reserve flow. A prominent example of this type of PVC check valve is the flapper valve found connected to toilet flush lever.
For the best results, customers should consult and work closely with an experienced valve manufacturer who will be able to lead them in the right direction. Find out more by reaching out to one of the many skilled PVC check valve manufacturers listed on our website today.
PVC Check Valves Informational Video