Red Seal Steamfitter/Pipefitter Practice Exam

What is the function of thermal expansion tanks?

1. To increase the flow rate through a system

2. To absorb excess pressure due to thermal expansion in a closed system

3. To prevent backflow in a piping system

4. To cool down heated fluids within pipes

The correct answer is: To absorb excess pressure due to thermal expansion in a closed system

The function of thermal expansion tanks is primarily to absorb excess pressure generated by the thermal expansion of water within a closed plumbing system. When water is heated, it expands, causing an increase in pressure. If this pressure is not managed, it can lead to potential damage to the system, such as bursting pipes or damaging valves. The thermal expansion tank provides a designated space where this extra volume can go, preventing pressure build-up. As the water expands, it pushes down on a diaphragm within the tank, which allows for controlled movement and absorption of the excess water. This mechanism helps maintain safe pressure levels within the system, ultimately enhancing the longevity and safety of plumbing systems. Other options relate to different functions within a piping system. Increasing the flow rate pertains to systems designed for improved fluid movement, preventing backflow involves the use of check valves or similar devices, and cooling down heated fluids is handled by cooling systems or heat exchangers. Each of these functions serves specific needs, but they do not address the critical issue of pressure management caused by thermal expansion.