WÄRTSILÄ Vasa R22, Instruction Manual

Page: 246 / 297

The contents of the elements (9) has an almost infinite force when
heated and is positively sealed. When the elements are heated,
this force is transmitted to the piston thus moving the sliding
valve towards the seat (11) to the by-pass closed position. This
force is opposed by a high spring force, which moves the sliding
valve to the heat exchanger closed position when the elements are
cooled. The high force available on heating is the basis of the fail
safe feature in which failure of the element would cause the
engine to run cold. The HT-thermostatic valve in main engine
installations are provided with a possibility for manual override.
19.4.5 Maintenance
Normally, no service is required. Too low a water temperature
depends on a defective thermostat, too high a temperature may
depend on a defective thermostat, although, in most cases, it
depends on a dirty cooler.
1 Remove the elements by unscrewing the pipe before the
valve and opening the cover.
2 Check the element by heating it slowly in water. Check
at which temperatures the element starts opening and is fully
open. The correct values can be found in chapter 01.; the lower
value for the water temperature is the opening temperature,
the higher for the fully open valve.
3 Change the defective element.
Check sealings and re-
place, if necessary.
4 Install the elements
22-9601 Cooling Water System 19
VASA 22 19 - 17