| |
Back Mechanical Gas Cushion | Up Utilitiesman Basic Volume 02 - Manual for electric, plumbing, water and other utilities | Next Chapter 5 Galley and Laundry Equipment |
this gas is stored often to ensure there is no leakage.
Liquid petroleum gas is heavier than air, settles in low
areas, and creates explosive hazards. When checking
for gas leaks, use a standard soap solution.
The possibilities of line failure are remote when
the construction recommended above is used. The
system piping material is subjected to a minimum
factory test of 700 psi. The generator tubes are
subjected to an ASME test of 900 psi. All valves and
Because of the large heat storage capacity of
accessories are rated at working pressures of 540 to
HTHW systems, the load demand change for the boiler
is slow and smooth. This characteristic provides for
improved and safer operation than that provided by the
saturated-steam cushion.
1,075 psi at 400°F. The weakest link in the piping
network lies within the generator tubing. The worst
likely failure is the loss of tubes, and therefore the
generator. The safety of the piping system is
maintained over the life of the installation because of
the absence of corrosion in the hot-water heating
systems due to boiler water treatment.
PIPING SYSTEM INSTALLATION
All piping in an HTHW system should be welded.
No screwed joints should be permitted, and flanges
should be allowed only where necessary, such as at
expansion joints, pumps, and generator connections.
Only schedule 40 black steel piping or better is used for
HTHW systems. Upon completion, the entire heating
Q30. What is the high-temperature range for most
military and federal heating plants?
Q31.
What are the two common ways of heating water
in HTHW systems?
Q32. To prevent oxygen corrosion in an HTHW
system, treat the water with chemicals to
produce whatppm of sodium sulfite?
system is subjected to a test of 450 psi that lasts for not
Q33. Should all piping in an HTHW system be
less than 24 hours.
welded? True/False
4-51
|