15 Questions
What is the minimum pressure rating required for blowoff or drain valves used in low-pressure steam boilers?
200 kPa (30 psi)
Where is the blowoff connection located in packaged firetube boilers?
At the bottom of the shell close to the back end
Which fittings are required by ASME BPVC IV on every hot water heating boiler?
Pressure gauges and altitude indicators
Where are blowoff connections typically located in boilers with water legs?
At the lowest point of each water leg
What is the minimum temperature rating required for valves used to blowoff or drain low-pressure steam boilers?
120°C (250°F)
What is the purpose of an expansion tank in a heating system?
To compress the air cushion inside the tank
According to ASME BPVC IV Part HG-709.2, what is a requirement for expansion tanks in systems designed to operate above 200 kPa?
They must have a minimum hydrostatic test pressure of 520 kPa
What is the purpose of isolation and drain valves in the piping to a bladder-style expansion tank?
To allow draining the tank without emptying the system
How does oxygen dissolved in the water in non-bladder style expansion tanks affect the heating system?
It can cause corrosion of steel piping and heating units
What does the presence of a shutoff valve in the connecting line between the tank and the hot water supply header allow?
Draining the tank without emptying the system
What type of gauge is used to indicate whether the hot water system is full?
Altitude gauge
What is the purpose of an expansion tank in a hot water heating system?
To store excess water due to expansion
What is a unique requirement for safety relief valves in hot water heating boilers?
The additional valves may be set to higher than the maximum allowable working pressure (MAWP)
What is the purpose of stop valves in hot water heating boilers?
To allow draining of the boiler without emptying the entire piping system
Why are siphons not required between the gauge and the boiler in hot water service?
Because hot water boilers are completely filled with water and generate no steam
Test your knowledge about the blowoff and drainage systems in different types of boilers, including the minimum pressure and temperature ratings for valves used in low-pressure steam boilers. Learn about the installation and purpose of blowdown valves.
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