Class 5 Boiler Practice Exam

What is the purpose of combination temperature and pressure relief valves on direct fired hot water supply boilers?

1. To increase pressure

2. To keep water temperature below 210°F and relieve at set pressure

3. For aesthetic purposes

4. To maintain system pressure

The correct answer is: To keep water temperature below 210°F and relieve at set pressure

The purpose of combination temperature and pressure relief valves on direct fired hot water supply boilers is to ensure safety by preventing excessive pressure and temperature within the system. These valves are designed to automatically relieve pressure when it reaches a predetermined set point, which helps to avoid potential boiler explosions or other dangerous malfunctions. Additionally, this type of valve keeps the water temperature below 210°F, thereby preventing overheating. Maintaining both temperature and pressure within safe limits is crucial in boiler operation. If the temperature rises too high or the pressure escalates beyond the predefined thresholds, the relief valve activates to discharge water and steam, ensuring that the operating conditions remain within safe and manageable levels. This mechanism is a vital aspect of boiler safety and performance efficiency. Other choices do not accurately reflect the primary function of these valves. Increasing pressure or maintaining system pressure does not address the need for safety relief, and aesthetic considerations are irrelevant in the context of safety devices like relief valves.