CSLB Class B General Contractor's License Practice Exam

Hot and cold water supply systems should be tested using which of the following?

1. 15 psi of air for an hour

2. 50 psi of air for 15 mins

3. 150 psi of water for a full 24 hours

4. None of the above

The correct answer is: 50 psi of air for 15 mins

Testing hot and cold water supply systems using air pressure is a common practice to ensure that there are no leaks in the system before it is put into operation. The requirement for testing with 50 psi of air for 15 minutes is traditionally recommended because this pressure level is sufficient to identify any leaks without being excessively high, which might risk damaging the system or causing false readings. The air testing method is a practical approach as it prevents water from filling the pipes and allows for early detection of leaks. If a drop in pressure is observed during the testing period, this indicates a potential problem that requires attention before the system is pressurized with water. This choice aligns with standard plumbing practices where air testing is commonly used, ensuring that the system is both safe and functional before the introduction of water. It also helps to avoid excessive strain on the pipes and fitting during the testing phase.