Plumbing Fixture - Dražice OKC 300 NTR/1MPa Operation And Installation Manual

2.3 PLUMBING FIXTURE

Each hot service water pressure heater must have a membrane spring loaded with a safety
valve. Nominal clearance of safety valves is defined by standard. The safety valve must be
easily accessible, as close to the heater as possible. The inlet pipes must have at least the
same clearance as the safety valve. The safety valve is placed high enough to secure dripping
water drain by gravity. We recommend mounting the safety valve onto a branch pipe. This
allows easier exchange without having to drain the water from the heater. Safety valves with
fixed pressure settings from the manufacturer are used for the assembly. Starting pressure
of a safety valve must be identical to the maximum allowed heater pressure and at least 20
% higher than the maximum pressure in the water main (Table 5). If the water main pressure
exceeds such value, a reduction valve must be added to the system. . No stop valves can be
put between the heater and the safety valve. During the assembly, follow the guide provided
by the safety equipment manufacturer.
It is necessary to check the safety valve each time before putting it into operation. It is
checked by manual moving of the membrane from the seat, turning the make-and-break
device button always in the direction of the arrow. After being turned, the button must click
back into a notch. Proper function of the make-and-break device results in water draining
through the safety valve outlet pipe. In common operation, such a check needs to be
implemented at least once a month, and after each heater shutdown for more than 5 days.
Water may be dripping off the drain pipe of the safety valve; the pipe must be open into the
air, pointed down; environment temperatures must not drop below zero. When draining the
heater, use the recommended drain valve. First, close the water supply into the heater.
Please find necessary pressure values in the below Table 5. For proper safety valve operation, a backflow
valve must be mounted on the inlets pipes, preventing spontaneous heater draining and hot water
penetrating back into the water main. We recommend that the hot water distribution from the heater was
as short as possible to minimise heat losses. At least one demountable joint must be mounted between the
tank and every supply pipe. Adequate piping and fittings with sufficiently dimensioned maximum
temperature and pressure values must be used.
Table 5
ADMISSIBLE
SAFETY VALVE OPERATING
OPERATING WATER
PRESSURE HEATER
[MPa] PRESSURE
[MPa]
0,6
0,7
1
MAX
PRESSURE IN
THE COLD
WATER PIPE
[MPa]
0,6 up to 0, 4 8
0,7 up to 0,56
1 up to 0,8
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