WÄRTSILÄ Vasa R22, Инструкция по эксплуатации, Страница: 279 / 297

replaced by a new one. Pressure and temperature switches can
be checked during operation.
a) Temperature switches: The switches are fitted into special pock-
ets and can thus be lifted off for checking also during operation.
The check should be carried out so that the sensor part of the
switch is immersed in liquid, e.g. oil, which is slowly heated.
Watch at which temperature the microswitch opens. Note that
there are two switching points to be checked in the double
switches. The correct temperature is stated in chapter 01 and is
normally stamped on the switch as long as the switch has not been
adjusted to another temperature. Connect the switch correctly
when mounting. Also the pockets are to be removed and cleaned
when the systems are emptied for other reasons.
b) Pressure switches: The manometer of the instrument panel
may be utilized for checking during operation as follows:
•
shut the ball cock on the common pipe to the manometer and
the switch,
•
open carefully the pipe union nut on the pressure switch so
that the pressure switch gives signal.
The alarm switch for too low prelube oil pressure is set for rising
pressure and, thus, this method does not give the correct value.
A rough check can however be made when taking into considera-
tion that the switch will display a value about 0.2 bar lower at
falling pressure.
All pressure switches can also be connected to a separate test
unit.
c) Pressure drop indicator: Remove the lube oil switch from the
filter and the fuel switch from the pipes.
Connect a hydraulic pressure test device (pump + manome-
ter) to the switch connection which is connected to the filter
inlet (the higher pressure).
Raise the pressure to the switching point which should be
1.5
±
0.3 bar. At this point a red indicator ring at the end of the
switch should be visible.
d) Indicator switches: These switches can easily be checked when
the engine is standing, for instance:
•
the mechanical overspeed trip device is tripped manually
and should give indication,
•
the control shaft is turned until the load indicating switch
operates. Check which load this corresponds to.
Note! Never set any of the alarm or stop switches out of function.
If any of the switches gives a false alarm the reason should be
found out and the problem must be remedied immediately.
23 Instrumentation and Automation 22-9601
23 - 4 VASA 22