16 Questions
What type of safety relief valves are commonly used in potable water heaters and hot water storage tanks?
Temperature and pressure safety relief valves
What is the maximum allowable working pressure for the water heaters described in the text?
Less than 1100 kPa
According to ASME BPVC Section IV, Part HLW-800, how many officially rated temperature and pressure safety relief valves should each water heater have?
At least one
What is the purpose of using temperature and pressure safety relief valves in potable water heaters and hot water storage tanks?
To protect against explosion dangers associated with super-saturated hot water
What standard is referred to for safety relief valve requirements for industrial and commercial potable water heaters in the text?
ASME BPVC IV, Part HLW-800
What type of water is used in the described potable water heaters and hot water storage tanks?
Cold potable water
What is the purpose of a temperature and pressure relief valve in a hot water system?
To relieve excess pressure caused by thermal expansion and high water temperatures
Where must safety relief valves be installed according to HLW-801?
With their spindles upright and vertical, with no horizontal connecting pipe
What is the construction of the pressure-sensitive element in a temperature and pressure relief valve?
A nonadjustable compression spring holds a disc shut against a seat
What type of temperature relief device uses the expansion and contraction of a rod and tube arrangement to open and close?
Another type that opens at 99°C and closes at 71°C
Why might additional overpressure protection be required for relief devices sensitive only to temperature?
Because they are insufficient for vessel protection
Where should safety relief valves be installed in relation to other components in the hot water supply system?
Based upon the component with the lowest maximum allowable working pressure rating
What action does the temperature sensitive element in a T&P valve take when exposed to high temperature?
Expands against the force of the compression spring
What type of safety relief valve is considered insufficient for vessel protection by ASME?
A safety relief valve sensitive to temperature only
What does the combination temperature and pressure relief valve provide protection for?
Overpressurization and dangerously high water temperatures
What is another type of temperature relief device that automatically recloses?
An expansion and contraction device opening at 99°C and closing at 71°C
Test your knowledge on the construction and operation of temperature and pressure relief valves for potable hot water heaters, designed according to ASME BPVC IV, Part HLW, operating at pressures and temperatures within specified limits.
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