Dražice OKC 250 NTR - Page 19

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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 regular operation, such a check needs to be carried
out at least once a month, and after each shutdown of the tank longer 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
tank, use the recommended drain valve. First of all, close water inlet in the tank. Find
necessary pressure values in the following table. For proper safety valve operation, a
backflow valve shall be mounted on the inlet pipes, preventing spontaneous heater draining
of the tank and hot water penetration back into the water main.
Required pressures - Table 10 - We recommend that the hot water distribution from the tank is as short as
possible in order to reduce heat losses.
Table 10
Tanks must be provided with a discharge valve mounted on the cold service water inlet to the heater for
potential disassembly or repair
SAFETY VALVE STARTING PRESSURE
(MPa)
ACCEPTABLE OPERATING OVER-
PRESSURE OF THE WATER HEATER
(MPa)
MAX COLD WATER PRESSURE IN
PIPING (MPa)
0,6
0,6
up to 0.48
0,7
0,7
up to 0.56
1
1
up to 0.8
FIgure 1