Backflow preventers protect public water systems that are run by the surveyor. They provide the highest quality of drinking water through a water faucet. Backflow preventers are very complex and important systems, so it is important to reset one if it is not in working condition.
Step 1 - Attach Hose and Check Pressure - Checking the CV1
Attach a high hose to test cock #2 and a low hose to test cock #3. To do this, you will open the low pressure bleed valve. Now you can test cock #3, do so slowly. Next, you will open test cock #2 and open the high pressure bleed valve.
Step 2 - Installing the Compensating Tee
On CV1, install the compensating tee on TC 2. Next you will install the short tube on TC 3. Then attach the high hose to the compensating tee.
Step 3 - Filling the Short Tube
Open TC 3 to fill the short tube and close TC 3. Next open TC 2 slowly. Open high A and vent C in order to expel air from the gauge and BFP. Now you can close vent C.
Step 4 - Closing the Shutoff
Close the shutoff on #2 and the shutoff on #1. The pressure is now captured in BFP. You can now open CV1. Remember, TC 2 must remain open at this time. If the needle on the gauge holds at 1.0 PSI or greater at the water level in the short tube, then CV 1 holds tight. Record this numerical value.
Step 5 - Closing the Valves
Close both the high and low pressure valves. Shut off valve #2. On CV2, close both TC 2 and TC 3. Move the short tube from TC 3 to TC 4. Move the compensating tee and the high hose from TC 2 to TC 3. Open the shutoff to #1.
Step 6 - Filling the Short Tube
Open TC 4 to fill the short tube and close TC 4. Next open TC 3 slowly and open vent C to expel air from the gauge and BFP.
Close C and close shutoff #1. The pressure is now captured in BFP. Open TC 4. TC 3 must remain open at this time. If the needle on the gauge holds 1.0 PSI or greater at the water level in the short tube, then CV 2 holds tight. Record this numerical value.
Step 7 - The Final Reset
Close all the TCs. Remove the high hose, compensating tee and all brass fittings. Next open the customer hose bib to flush out any potential debris from the line. Now you open shutoff #1, then shutoff #2. Finally, you can close the customer hose bib.
Backflow preventers work by using a valve that prevents water from backing up into a supply line. It allows water to flow through the valve and, when no water is present, it closes to prevent water contamination from another source.