THERMO 2000 VOLTMAX 23, Инструкция по использованию и уходу

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TURBOMAX Use and Care Manual with Installation Instructions July 2014 Page
15
PIPING SYSTEM PRESSURIZATION
The objective of system pressure control is to
limit the pressure on all system equipment to its
allowable working pressure, to maintain
minimum pressure for all normal operating
temperatures, to vent air and prevent cavitation
at the pump suction and boiling of system boiler
water, and to accomplish these objectives with a
minimal addition of new water.
The excess boiler water volume in the system,
resulting from increased temperature, is stored
in the expansion tank during periods of high
operation temperatures and is returned to the
system when the system boiler water level is
lower.
The expansion tank must be able to store the
required volume of boiler water during maximum
design operating temperatures without
exceeding the maximum allowable operating
pressure, and to maintain the required minimum
pressure when the system is cold. Contact your
installing contractor, plumbing supply house, or
local plumbing inspector for assistance.
The point where the expansion tank is
connected should be carefully selected to avoid
the possibility that normal operation of automatic
check or manual valves will isolate the tank from
a hot boiler or any part of the system. Pre-
charged diaphragm expansion tanks are
preferable to air control.
They have a balloon-like bladder (diaphragm or
membrane) within the tank that contains air.
The bladder does not fill the complete tank and
is inflated prior to filling the system to the
pressure setting of the makeup water pressure
regulator ( or fill pressure reducing valve).
The expansion tank should be located at the
boiler outlet with the pump located either just
upstream or just downstream from the boiler.
Make-up systems must be employed as required
by codes. Automatic fill valves must be used
with back flow preventors as required, to
maintain the minimum system pressure by
supplying water to make up for leakage.
The safety relief valve installed on a hot water
boiler in accordance with ASME Boiler and
Pressure Vessel Code limits the maximum
pressure on the boiler. Since it is a safety
device, it should not be considered an operating
control.
Oxygen should be excluded from the system to
maintain corrosion-free characteristics, both in
pressurization and in the operating cycle. This
precludes the use of air in direct contact with the
water as a pressurization means.
Installation of manual air vent or automatic air
vent devices prevents air accumulation in the
system. Air vents should be installed at all high
points to remove trapped air during initial
operation and to ensure that the system is tight.
Check the air vent devices regularly to purge air
out of the system. Protect yourself to make sure
that the hot boiler water is directed away from all
persons or areas where injury or damage could
occur.
Expansion tank sizing
Sizing of the expansion tank depends on the
total volume of the system, the maximum and
minimum system pressures and temperatures,
the piping material, the type of tank, and how it
is installed.
To find the expansion tank sizing:
First inspect the piping layout.
Second, note all the elements through which
boiler water circulates from pump discharge to
pump suction (i.e. TURBOMAX tank, boiler(s),
storage tank, tubes or pipes)
Third, measure pipes length and note the pipe
diameter and material of the circuit.
Fourth, calculate for each element
(TURBOMAX
®
tank, boiler(s), storage tank,
tubes or pipes and other equipment) the water
content.
Fifth, sum all the water content of each item in
the circuit. Used Table 5 to measure the water
content of tubes, pipes, TURBOMAX
®
, storage
tank.
Finally size the expansion tank, using Table 6,
Table 7. The following data are needed: the
total volume of the system, the maximum and
minimum system pressures and temperatures,
the piping material, the type of tank.