Backflow Assembly Testers should be aware of a new Double Check Detector Assembly (DCDA) style. DCDAs are found on fire sprinkler systems to prevent backflow and to detect up to 2 GPM flow conditions through the bypass piping. This new assembly is called a DCDA Type II and performs the same as the standard DCDA Type I. Let’s examine the differences between the two.

A standard DCDA Type I assembly consists of a main line double check valve assembly with a bypass containing a water meter and an independent double check valve assembly. The bypass allows water flow to completely go around the main double check valve assembly. It is connected at the upstream side of the first check valve and at the downstream side of the second check valve. The water service is protected from backflow by two double check valve assemblies- one on the mainline and one on the bypass lines.

The DCDA type II assembly consist of a main line double check valve assembly with a bypass containing a water meter and a single check valve. The bypass is connected between the first and second check valves on the main assembly and on the downstream side of the second check valve. This assembly uses the first check valve on the main assembly, in combination with the single check valve on the bypass, to provide the double check valve protection. The main line double check valve assembly works the same as the Type I. It is important to note that the bypass assembly is not considered a complete separate assembly on USC’s approved list, like it is for the Type I assembly. The single check valve is listed with a model number on it so it can be replaced if needed.

The new Type II assembly provides some advantages over the Type I assembly. One such advantage is the Type II assembly provides a cost savings over the Type I assembly due to one less check valve. Additionally, a lower head loss pressure can result across the entire assembly. 

Both a Type I and Type II DCDA assembly provides the same protection for backflow. As these become more popular in the market, testers will need to become familiar with them. They can be easily identified by the placement of the bypass loop as well as the metal identification tag. Check out  BATalk’s issue 22  for information on testing and documenting the DCDA Type II.  



Authored by Richard Wagoner, Washington Certification Services

Peggy Barton, former Director of Washington Certification Services, has retired effective May 1st. Rachel Neville is the new interim director at WCS. Rachel is a certified BAT, recipient of the ABC's Robert C. McAnespie Outstanding Certification Officer Award and has managed the BAT program for 8 years. We here at WCS want to thank Peggy for 38 years of outstanding service and congratulate Rachel on her new position.

Authored by Deborah Diggins, Washington Certification Services

Testing a backflow assembly can be an overwhelming process- especially if things start to go wrong in the very beginning. One important method can save the tester time, embarrassment and frustration. If performed properly at the beginning, it can set the stage for a smooth and successful test. This method is referred to as  Notify, Identify, Inspect, and Observe (NIIO) . Let’s break down each part one at a time.

The first step when performing a backflow assembly test is to notify the occupants and owner that the water will be shut off for a short period of time. This allows the occupants to make arrangements if necessary and alert employees. If the assembly is installed on a fire sprinkler system, the fire department and the owner’s alarm monitoring company must also be contacted. No one wants firemen to show up at their test as soon as they close the shutoff valves because the fire sprinkler system went into alarm.

Next, it is important to identify the type of assembly you are testing. This may sound pretty self-explanatory, but you would be surprised at how many people try testing a reduced pressure backflow assembly (RPBA) as a double check valve assembly (DCVA) simply because of improper identification. Remember to check the identification tag on the assembly for make, model, size and serial number.

The third step is to inspect the assembly for the required components. All parts include upstream and downstream shutoff valves and test cocks. Record any non-factory parts that have been installed on your test report form. Remember to check  USC’s List of Approved Backflow Prevention Assemblies  with approved replacement and alternate shut-off valves. If a component is not listed, it is not approved for use in that assembly. Notify the owner and the water purveyor of an improper assembly.

Finally, observe the area around the assembly for signs of leakage. If water, mold or damp spots exist, the assembly may need repair. Further testing will yield more information. Further inspect the installation for unsafe conditions. Make sure the assembly is not installed in an area where water discharge or leakage would create a hazard, like near electrical equipment. It is the responsibility of the tester to note on the test report form any information that would make a backflow assembly not adequate for its purpose.

Spending a few minutes at the beginning of a test to  NOTIFY occupants/fire department,  IDENTIFY  the assembly,  INSPECT  the components, and  OBSERVE  the surroundings can save a lot of time and aggravation. It is always better to do it right the first time instead of having to explain to an owner why the fire department is present. Take time to execute the  NIIO  method whenever testing a backflow assembly to ensure proper results.



Authored by Richard Wagoner, Washington Certification Services