FREE Journeyman Plumbers Water Supply and Distribution Questions and Answers

Question 1

A newly installed copper potable water distribution system in a commercial building must be tested for leaks. According to most model plumbing codes, what is the minimum required hydrostatic test pressure?

Accepted Answer

1.5 times the working pressure, but not less than 100 psi

Answer

Most plumbing codes, including the International Plumbing Code (IPC) and Uniform Plumbing Code (UPC), require a hydrostatic test pressure of at least 1.5 times the system's working pressure. Additionally, there is often a minimum requirement, typically 100 psi, to ensure a thorough test even in low-pressure systems. This high pressure will reveal any leaks at joints or defects in the piping.

Question 2

In a residential hot water supply system with a backflow preventer or check valve installed at the source, what device is essential to protect the water heater and piping from excessive pressure due to thermal expansion?

Accepted Answer

A potable water expansion tank

Answer

When water is heated, it expands. In a 'closed' system, created by a check valve or backflow preventer, this expansion creates a dangerous increase in pressure. A potable water expansion tank is designed with an air bladder to absorb this expanded water volume, keeping the system pressure within a safe range.

Question 3

A plumber is sizing a water service pipe for a single-family home using the Water Supply Fixture Unit (WSFU) method. The total WSFU load is 28, the developed length to the furthest fixture is 120 feet, and the static street pressure is 55 psi. Using a typical IPC/UPC sizing table, what is the minimum required size for the copper water service pipe?

Accepted Answer

1 inch

Answer

Based on typical plumbing code sizing tables (like those in the UPC or IPC), you would find the appropriate pressure range (e.g., 46-60 psi), then cross-reference the developed length column (e.g., 100-150 feet) with the WSFU load. For a load of 28 WSFU at that length and pressure, a 3/4" pipe is typically insufficient, making a 1-inch pipe the correct minimum size to maintain adequate pressure and flow.

Question 4

Which of the following locations would specifically require the installation of a water hammer arrestor according to most modern plumbing codes?

Accepted Answer

On the water supply lines for a clothes washing machine

Answer

Water hammer is caused by the sudden stoppage of water flow, creating a shockwave. Modern codes require water hammer arrestors to be installed near any quick-closing valves. The solenoid valves in a clothes washing machine are a prime example of quick-closing valves, making arrestors mandatory on both the hot and cold supply lines to prevent damage to the pipes.

Question 5

A plumber is performing a field test on a Reduced Pressure Principle (RP) backflow preventer (ASSE 1013). During the test of the relief valve, what is the minimum differential pressure at which the valve must begin to open and drip?

Accepted Answer

2.0 psid

Answer

According to the ASSE 1013 standard for Reduced Pressure Principle backflow prevention assemblies, the relief valve is a critical safety component. During a field test, it must open and begin to discharge water when the pressure differential between the check valves drops to 2.0 psid (pounds per square inch differential) or above. This ensures it will function correctly to prevent backflow.

Journeyman Plumbers Exam Practice Test

Journeyman Plumbers Exam Practice Test

FREE Journeyman Plumbers Water Supply and Distribution Questions and Answers