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Questions and Answers
What is the maximum operating pressure of commercial and industrial potable water heaters and hot water storage tanks?
What is the maximum operating pressure of commercial and industrial potable water heaters and hot water storage tanks?
What is the maximum operating temperature of commercial and industrial potable water heaters and hot water storage tanks?
What is the maximum operating temperature of commercial and industrial potable water heaters and hot water storage tanks?
What type of valve is commonly used in potable water heaters and hot water storage tanks?
What type of valve is commonly used in potable water heaters and hot water storage tanks?
According to ASME BPVC Section IV, Part HLW-800, what is the minimum requirement for safety relief valves in industrial and commercial potable water heaters?
According to ASME BPVC Section IV, Part HLW-800, what is the minimum requirement for safety relief valves in industrial and commercial potable water heaters?
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What is the basis for determining the pressure setting of the relief valve in industrial and commercial potable water heaters?
What is the basis for determining the pressure setting of the relief valve in industrial and commercial potable water heaters?
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Where must safety relief valves be installed in industrial and commercial potable water heaters?
Where must safety relief valves be installed in industrial and commercial potable water heaters?
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How must the spindles of safety relief valves be oriented in industrial and commercial potable water heaters?
How must the spindles of safety relief valves be oriented in industrial and commercial potable water heaters?
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What is the maximum length of interconnecting piping allowed between a safety relief valve and the water heater vessel?
What is the maximum length of interconnecting piping allowed between a safety relief valve and the water heater vessel?
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What is the recommended minimum size of pipings used to mount the safety relief valve?
What is the recommended minimum size of pipings used to mount the safety relief valve?
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Where should the outlet of the safety relief valve point when installed in a horizontal position?
Where should the outlet of the safety relief valve point when installed in a horizontal position?
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What type of valve is considered insufficient for vessel protection by ASME?
What type of valve is considered insufficient for vessel protection by ASME?
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What is the primary function of the pressure element in a temperature and pressure relief valve?
What is the primary function of the pressure element in a temperature and pressure relief valve?
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At what temperature does the temperature element in a T&P valve open?
At what temperature does the temperature element in a T&P valve open?
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How often should T&P valves receive try lever tests?
How often should T&P valves receive try lever tests?
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What happens to the wax in the thermal element of a T&P valve when exposed to high temperatures?
What happens to the wax in the thermal element of a T&P valve when exposed to high temperatures?
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What happens to a fusible element temperature relief device after it melts at 99°C?
What happens to a fusible element temperature relief device after it melts at 99°C?
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Study Notes
Safety Relief Valves in Commercial and Industrial Potable Water Heaters
- Safety relief valves are installed on commercial and industrial potable water heaters and hot water storage tanks, designed according to ASME BPVC IV, Part HLW.
- These heaters and tanks operate at pressures not exceeding 1100 kPa and temperatures not exceeding 99°C.
- Safety relief valves protect against explosion dangers associated with super-saturated hot water.
Temperature and Pressure Safety Relief Valves
- Most potable water heaters and hot water storage tanks use temperature and pressure safety relief valves.
- These valves protect against both over-pressurization and high water temperatures.
- ASME BPVC Section IV, Part HLW-800 refers to safety relief valve requirements for industrial and commercial potable water heaters.
Installation Requirements
- Safety relief valves must be installed not lower than 100 mm from the top of the shell.
- Valves must be directly connected to the water heater or a fitting connected to the water heater.
- Spindles must be upright and vertical, with no horizontal connecting pipe.
- No piping or fitting used to mount the safety relief valve can be smaller than the valve inlet.
- Safety relief valves shall not be connected to an internal pipe or a cold water feed line.
Combination Temperature and Pressure Relief Valves
- These valves provide protection for both over-pressurization and high water temperatures.
- The pressure element opens to relieve excess pressure, usually caused by thermal expansion.
- The temperature element opens when the water temperature rises to about 99°C.
- Unlike safety relief valves, T&P valves do not operate with a pop action when over-pressurization occurs.
Temperature-Sensitive Element
- The temperature-sensitive element consists of a wax-filled thermostatic sensor probe that extends into the water storage tank.
- When exposed to high temperature, the wax expands, lifts the valve disc off its seat, and discharges the overheated water.
- When the temperature returns to a safe level, the wax contracts, and allows the spring to reseat the valve.
Testing and Maintenance
- It is recommended that T&P valves receive annual try lever tests.
- Various types of temperature relief devices can be used, but they must always have additional pressure relief.
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Description
Learn about safety relief valves in commercial and industrial potable water heaters, their design, operating conditions, and importance in preventing explosion dangers.
