How to Field Test Backflow Preventers

How to Field Test Backflow Preventers

Table of Contents

1. Introduction to the Double Check Valve Backflow Prevention Assembly (DC)
2. Parts of the DC
   1. Test Coock Number One
   2. Shut Off Valve Number One
   3. Test Coock Number Two
   4. Check Valve Number One
   5. Test Coock Number Three
   6. Check Valve Number Two
   7. Test Coock Number Four
   8. Shut Off Valve Number Two
3. Preliminary Steps before the Field Test Procedure
   1. Notify
   2. Identify
   3. Inspect
   4. Observe
4. Field Test Procedure
   1. Testing the Tightness of Check Valve Number One
   2. Bleeding Water through Test Coocks
   3. Installing Appropriate Fittings
   4. Testing the Tightness of Check Valve Number Two
5. Recording Differential Pressure Readings
   1. Check Valve Number One
   2. Check Valve Number Two
6. Concluding the Test

Double Check Valve Backflow Prevention Assembly (DC)

Backflow is a common issue that occurs when the flow of water in a plumbing system is reversed, contaminating the potable water supply. To prevent backflow, a double check valve backflow prevention assembly (DC) is used. This article aims to provide a comprehensive overview of the DC, its various parts, the field test procedure, and the necessary steps to ensure its proper functioning.

Introduction to the Double Check Valve Backflow Prevention Assembly (DC)

The double check valve backflow prevention assembly, commonly referred to as the DC, is a crucial component in plumbing systems as it prevents the reverse flow of water, which could potentially contaminate the household's potable water supply. The DC consists of multiple parts, each serving a specific purpose in ensuring the prevention of backflow.

Parts of the DC

The DC is composed of several key parts that work together to maintain the integrity of the plumbing system. These parts include:

1. Test Coock Number One
2. Shut Off Valve Number One
3. Test Coock Number Two
4. Check Valve Number One
5. Test Coock Number Three
6. Check Valve Number Two
7. Test Coock Number Four
8. Shut Off Valve Number Two

Each of these parts plays a crucial role in the proper functioning of the DC and the prevention of backflow.

Preliminary Steps before the Field Test Procedure

Before conducting the field test procedure on the DC, it is essential to complete a series of preliminary steps to ensure accurate results and a thorough evaluation:

1. Notify: Inform all relevant parties about the upcoming field test procedure to ensure proper coordination.
2. Identify: Clearly identify the DC and its various components, ensuring a clear understanding of its location and operation.
3. Inspect: Perform a thorough inspection of the DC, checking for any visible damage, leaks, or signs of wear.
4. Observe: Take note of any abnormal flow patterns, unusual noises, or other indicators that may suggest a malfunctioning DC.

Completing these preliminary steps will help to set the foundation for a successful field test procedure.

Field Test Procedure

Once the preliminary steps have been completed, the field test procedure can begin. This procedure involves a series of steps to check the tightness of the check valves and ensure the proper functioning of the DC. The following are the steps involved in the field test procedure:

1. Testing the Tightness of Check Valve Number One

   • Bleed water through test coocks to eliminate foreign material by opening and closing each test coock.
   • Install appropriate fittings if test coock number three is not at the highest point of the check valve body.
   • Attach a bleed-off valve arrangement to test number two and connect the hose from the high side of the field test kit to the bleed-off valve.
   • Open test coock number two and bleed all air from the field test kit.
   • Close the high side bleed needle valve.
   • Open test coock number three to fill the test coock number three or tube if attached, ensuring the water level is above the top of the check valve body.
   • Close test coock number three and close the shut off valve.

2. Testing the Tightness of Check Valve Number Two

   • Attach a bleed-off valve arrangement to test coock number three and connect the hose from the high side of the field test kit to the bleed-off valve.
   • If test coock number four is not at the highest point of the check valve body, install a vertical tube or pipe on test coock number four.
   • Open test coock number three and bleed all air from the field test kit.
   • Close the high side bleed needle valve.
   • Open test coock number four to fill the test coock number four or tube if attached, ensuring the water level is above the check valve body.
   • Close test coock number four and close the shut off valve.

3. Recording Differential Pressure Readings

   • The readings indicated on the field test kit represent the differential pressure across check valve number one and should be recorded accordingly.
   • Repeat the same process for check valve number two and record the differential pressure.

4. Concluding the Test

   • Close all test coocks and open shut off valve number one.
   • Remove all test equipment and fittings.
   • Open shut off valve number two.
   • Record the differential pressure readings for check valve number one and check valve number two.
   • Assess the overall assembly status.

With the completion of the field test procedure, a thorough assessment of the DC's functionality can be made, ensuring its effectiveness in preventing backflow.

Highlights

• The double check valve backflow prevention assembly (DC) is a crucial component in plumbing systems.
• The DC consists of various parts, including test coocks, shut off valves, and check valves.
• The field test procedure is essential to ensure the proper functioning of the DC.
• Differential pressure readings across check valves help assess the integrity of the assembly.
• Regular maintenance and testing of the DC are necessary to prevent backflow and ensure water safety.

FAQ

Q: Why is it important to test the tightness of check valves in the field test procedure? A: Testing the tightness of check valves is crucial as it helps ensure that they are functioning correctly and preventing backflow effectively.

Q: What should be done if the water level is not above the top of the check valve body during the procedure? A: If the water level is not above the top of the check valve body, a vertical tube or pipe must be installed to raise the water level to the required height.

Q: How often should the field test procedure be conducted on the double check valve backflow prevention assembly? A: It is recommended to conduct the field test procedure at least annually to ensure the ongoing effectiveness of the double check valve backflow prevention assembly.

Q: How can the overall assembly status be assessed after the test? A: The overall assembly status can be assessed by evaluating the differential pressure readings, checking for any abnormalities, and ensuring that all parts are functioning as intended.

Q: What are the consequences of a malfunctioning double check valve backflow prevention assembly? A: A malfunctioning assembly can lead to backflow, which can contaminate the potable water supply, compromising the safety and quality of the water.

Q: Are there any specific maintenance requirements for the double check valve backflow prevention assembly? A: Regular maintenance, including cleaning, inspection, and testing, is necessary to ensure the ongoing effectiveness of the assembly. Consult with a professional plumber for specific maintenance requirements.

Q: Where can I find more information about the double check valve backflow prevention assembly? A: For more detailed information and guidelines, refer to the specifications and recommendations provided by plumbing authorities and organizations.

Resources

• Plumbing Association website
• Water Safety Authority website