For Dangerous Backflow Prevention Assignments Plumbers Frequently Go With The RPD Valve
With the advent hof more and more potentially harmful chemicals in modern living, and the addition of complex add-ons to our plumbing system such as fire sprinkler systems and underground irrigation systems, there are more and more opportunities for contaminated water to be sucked back into the potable water system through a siphoning effect.
The danger inherent in sprinkler and fire prevention systems exists because the water often is sitting and not flowing. Water at the opening of the pipes is exposed to contaminants in the ground in the case of sprinkling systems, and in the house or from a fire in the case of the fire extinguishing systems. On occasion the contaminated water can be drawn back through sprinkling or fire prevention systems through a siphoning effect, and the potable system will be contaminated.
When contaminated water is sucked back into the potable system it is called backflow. When contaminated water flows directly from one contaminated source into the potable drinking water system that is called “cross connection.” In order to prevent these events from taking place, various devices called backflow prevention devices have been developed. Different types of backflow have different levels of danger. Depending on the level of danger, the state may require greater or lesser levels of backflow prevention.
One of the strongest commercial strength backflow preventers is called the RPD, or reduced principle backflow preventer. This device is frequently used commercially, and less often residential, although it is often used in fire prevention sprinkling systems The water in the fire sprinkler system sits for long periods of time, and sometimes anti freeze or anti corrosives are introduced into the system to keep the water lines patent. Should these chemicals be sucked back into the potable water system, it might create great harm.
The RPD valve is a nifty device that consists of two check valves installed in line in a tubing. In a non dangerous backflow situation we assume that if the one check valve doesn’t work than the other will. If the dangers inherent in a potential backflow contamination are severe, we think differently. Check valves are designed to keep the water flowing in one direction, from upstream to downstream. If the flow reverses, than the downstream valve will shut off. But what happens if the pressure increases and overwhelms the downstream valve. Now, in a dangerous backflow situation we are worried that the pressure will overwhelm the upstream valve. as well. So we have a pressure release valve in between the two check valves. The pressure release valve is made so that when water flows in the normal direction, it will flow into the chambers on both side of the pressure release valve, and keep it shut, through equal pressure exerted on both sides. When the flow of water reverses, the water cannot reach to the outer side of the pressure release valve, so the valve opens, and water flows out of the tube, releasing the pressure which was building up in the gap between the two check valves. This added measure of safety, provides the greater protection from backflow needed in a high danger situation.
While each state has their own set of regulations, RPD valves are generally most often required for commercial installations. When they are used in the home it is usually when the home has a sprinkler system,or where the irrigation system is designed to have contact with dangerous insecticides.If you have any questions about the use of backflow preventers in your home, contact a plumber in your area who is qualified to install backflow prevention devices.
Thanks to A-1 Plumbing of Baltimore, a Baltimore plumbing company for sponsoring this article .If you happen to live in the Greater Baltimore area, And have a question about backflow prevention. Give us a call. Our licensed plumbers are qualified to install backflow devices and will be happy to assist you.
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