What is a dual check valve, and why is it important to your safety and the safety of your family?

We will attempt to answer those two questions about dual check valve assemblies  in this article.  If you have specific questions you can call us at (817) 996-2000.

What is a dual check valve?

A dual check valve, or double check assembly (DCA) is a backflow prevention device designed to protect water supplies from contamination. It is also a valve used in air brake systems on heavy trucks.

It consists of two check valves assembled in series. This employs two operating principles: firstly one check valve will still act, even if the other is jammed wide open. Secondly the closure of one valve reduces the pressure differential across the other, allowing a more reliable seal and avoiding even minor leakage.

To understand better about this, an understanding of backflow is necessary.

What is backflow?

A basic understanding of your water system is necessary in order to understand back flow.  Water travels from your city’s water supply to your home or business by water pressure.  The clean water is basically pushed to your home or business using pressure.  It works that way day in, day out, 365 days per year, and everyone is happy and healthy.  But . . .

There are occasions when that water pressure will drop.  A busted water main is one such occasion.  A major fire requiring several water hydrants to be opened is another situation which will drop the water pressure.  When those things happen, the water pressure may drop so drastically as to actually reverse the flow of water in the system.  This is backflow, and it means that contaminated water from homes and businesses can flow back into the City’s potable water supply.

And it would do exactly that if it were not for back flow preventors like a dual check valve.  These are valves which only allow water to flow in one direction, the correct direction, so that if the pressure drops, and the flow reverses, it cannot get passed these valves.

Dual check valves are produced by companies like Ames, Watts, and Febco, and only approved backflow devices are allowed in most cities in the United States.

In addition, only licensed and certified backflow technicians, or backflow testers, are allowed to install, repair, or inspect backflow devices.

Who is required to have backflow inspections?

In the United States most commercial buildings are required to have annual backflow inspections.  In addition, residential buildings with irrigation are also required.  For a full list of required properties, and also a list of certified backflow inspectors, check with your city’s backflow prevention program, usually listed under “cross connection” on their website.

We are City Backflow Testing, serving the Greater Fort Worth area.  You can call us to have your questions answers, or to find out about our rates or to make an appointment.  We are trusted backflow testers in every major town in Tarrant County, so you can count on getting pertinent, accurate, and trusted information from us regarding dual check valves and back flow.