The term «duplex» refers to a double check valve assembly. These products are an excellent method for control of solids and gases in the line of site for a plumbing system. The design features incorporate an air release at the opening of the assembly. The valve is normally secured by two clips that allow it to be operated from the side by means of a spring mechanism, usually consisting of a screw threading device at its end. This assembly is intended to prevent the backflow of water from the non-potable to potable source, usually because of back pressure or siphoning by way of gravity according to national plumbing codes. A double check valve with drain can be a very effective, economical and reliable component when it is utilized for the regulation of solids inside the underground storage tanks of domestic as well as commercial use.
It is extremely important to have the right equipment and supplies when working with the liquids that need to be in place within an underground storage tank. Such equipment and supplies make up a comprehensive «checks and balances» approach to ensuring that the entire system is working properly and efficiently. Double check valves are often used as valves for the purpose of backflow prevention in order to protect the integrity and longevity of the storage tanks of domestic and commercial use. A double check valve assembly is often used with other types of valves to provide for the complete safety measure of the entire system.
They are specifically designed to serve as an additional layer of protection for the stored liquids and gases inside the underground storage tanks. They provide an effective means of preventing or slowing down the backflow of fluid or gas from reaching the surface of the ground. They also play an important role in the maintenance of the safety of the fire protection systems in an environment where the liquids and gasses in question are subject to very high temperatures or corrosive elements. Double check valves and other types of backflow prevention devices are often used in fire sprinkler systems in both commercial and domestic installations.
The reason why they are so commonly found in such trusted areas, like fire sprinkler systems, is that the existence of these components are required by plumbing codes in most regions of the country. The plumbing codes in these areas usually specify the presence of certain components as being dependent on a safe drinking water supplies for the local population. The presence of a double check valve assembly will ensure the presence of the needed elements in this regard.
There are basically two different types of double check valve assembly: the first type has two upstream holes, while the second type has one upstream hole and one downstream hole. The upstream holes are positioned close to the earth’s surface. The downstream holes are placed deep into the ground, where pressure forces will prevent the assembly from separating from the supporting rock, thus preventing the excess pressure from building up. Naturally, both of these components will be subject to wear and tear over time, and thus require replacement.
Typically, these valves have an open contact face, which allows the flow of both liquids and gasses from their respective outlets to vary as they desire. In order for the valves to have a proper and safe working condition, they need to be closed as soon as there is no forward pressure in either direction. The pressure inside the system will then force both valves to open, thus allowing the desired flow to occur. Double check valves that lack this vital component will certainly not be able to maintain a proper working condition, and therefore will need to be replaced.
The water hammer refers to the occurrence of sudden, abnormal flow reversal in a watertight system. It may be caused by either a pipe blockage or possibly a crack in the pipe lining. As the name implies, the water hammer will cause a tremendous surge in the downstream pressure, causing pipes to burst and pressure to build behind the valve. To prevent such an occurrence, it is very important that both the pressures are in equilibrium, meaning that the upstream pressure should be equal to the downstream pressure before the valve opens. However, if there is an abnormality, such as a crack in the piping, then the downstream pressure will suddenly exceed the upstream pressure, essentially forcing the valve to close, effectively shutting off the water flow. This is what is commonly referred to as a water hammer.
These problems are typically more of an annoyance than anything else, but they can be extremely hazardous when they occur. As these valves rely on the pressure between the pipe linings and the water pipes, if there is any kind of blockage, crack or other damage to these elements, the flow of the liquid will be severely affected. For this reason, it is crucial that regular maintenance is performed on these pieces of equipment. This maintenance includes not only inspections of the pipes, but also of the pump and other components as well.