In a situation where water continues to flow from the sight tube during the testing of the second check valve of a double check valve assembly, what does it imply if the gauge reading goes to zero after opening the bleed off valve?

In a situation where water continues to flow from the sight tube during the testing of the second check valve of a double check valve assembly, what does it imply if the gauge reading goes to zero after opening the bleed off valve?

• A. Check valve number one is leaking
• B. Shut off valve number two leaks with back pressure
• C. No leaks are present
• D. The system is functioning normally

Answer: (B)

When a gauge reading drops to zero after opening the bleed-off valve during the testing of the second check valve in a double check valve assembly, this indicates a potential problem with the system. The fact that water continues to flow from the sight tube suggests that water is potentially leaking past a check valve or through another mechanism. If the gauge reads zero after the bleed-off valve is opened, it implies that there is insufficient pressure or containment in the system, which could be due to a leak in the second shut-off valve. Specifically, it suggests that this valve may be leaking under back pressure, allowing water to escape and causing the gauge to drop. This phenomenon occurs because the back pressure is not being contained, which results in a pressure drop in the system and is reflected in the gauge reading. Therefore, the conclusion that the second shut-off valve is leaking under back pressure adequately explains the observed behavior of the pressure gauge and the continuous flow from the sight tube, indicating a malfunctioning component in the backflow prevention assembly.

When a gauge reading drops to zero after opening the bleed-off valve during the testing of the second check valve in a double check valve assembly, this indicates a potential problem with the system. The fact that water continues to flow from the sight tube suggests that water is potentially leaking past a check valve or through another mechanism.

If the gauge reads zero after the bleed-off valve is opened, it implies that there is insufficient pressure or containment in the system, which could be due to a leak in the second shut-off valve. Specifically, it suggests that this valve may be leaking under back pressure, allowing water to escape and causing the gauge to drop. This phenomenon occurs because the back pressure is not being contained, which results in a pressure drop in the system and is reflected in the gauge reading.

Therefore, the conclusion that the second shut-off valve is leaking under back pressure adequately explains the observed behavior of the pressure gauge and the continuous flow from the sight tube, indicating a malfunctioning component in the backflow prevention assembly.