During hydrostatic testing of a dry system, the dry-pipe valve clapper must be latched open or removed.

During hydrostatic testing of a dry system, the dry-pipe valve clapper must be latched open or removed.

• A. Latched open or removed
• B. Removed only
• C. Latched closed
• D. Left in place

Answer: (A)

In a dry-pipe system the dry-prop valve’s clapper normally holds back water to keep the piping dry until system operation begins. For a hydrostatic test, you want the water to fill the dry piping and reach the test pressure without the clapper restricting flow. Latching the clapper open or removing it ensures the valve won’t close or restrict flow during the test, allowing a proper fill and accurate pressure readings. If the clapper stayed in its normal position (or remained in place and closed), air could be trapped or the water could be blocked, leading to an unreliable test. After testing, the system is restored to its normal configuration.

In a dry-pipe system the dry-prop valve’s clapper normally holds back water to keep the piping dry until system operation begins. For a hydrostatic test, you want the water to fill the dry piping and reach the test pressure without the clapper restricting flow. Latching the clapper open or removing it ensures the valve won’t close or restrict flow during the test, allowing a proper fill and accurate pressure readings. If the clapper stayed in its normal position (or remained in place and closed), air could be trapped or the water could be blocked, leading to an unreliable test. After testing, the system is restored to its normal configuration.