Backflow Prevention Practice Exam

A check valve field test reported value of 0.8 psid (5.5 kPa) indicates what condition?

1. A passing check valve

2. A broken or failed spring

3. Debris in the check seat

4. Disc softening or decay

The correct answer is: Disc softening or decay

A reported value of 0.8 psid (5.5 kPa) from a check valve field test is indicative of potential issues with the check valve's functionality. This specific pressure differential is not typical for a properly functioning check valve. In fact, such a reading can suggest that there is a problem with the condition of the valve's disc. When the disc of a check valve begins to soften or decay, it can fail to create a proper seal when the pressure changes. This results in some level of backflow or reduced pressure performance, which directly relates to the lower-than-expected pressure differential. Properly functioning check valves should maintain higher pressures, typically indicating that the disc is in good condition and sealing effectively against backflow. In this context, while there may be possibilities like debris in the check seat or issues with the spring, these would usually manifest in different ways in the pressure readings, typically showing signs of complete failure or blockage. Therefore, the reading of 0.8 psid is most consistent with the scenario of disc softening or decay, as it suggests that the seal is compromised due to material degradation.