WÄRTSILÄ 41508, Инструкция по эксплуатации

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be cha nged only by cha nging t empera ture element a ssemblies w hich
is easily a ccomplished by un screwing t he housing. The va lve is ent irely
self-contained, and there are no external bulbs or lines to become
damaged or broken. There are no packing glands to tighten and no
part s t o oil.
Water flow in thermostatic valve
The power creating medium utilizes the expansion of the element
content s (9), w hich rema ins in a semi-solid form a nd is h ighly sensit ive
to tempera ture cha nges. Most of the expansion ta kes place during t he
melting period of approximately two minutes over a temperature
cha nge of approxima tely 8.5°C .
The th ermosta tic valve is provided wit h tw o or more elements (10),
depending of the engine size. If failure of one element occurs, the
rema ining element s w ill ta ke over with only a slight cha nge in opera t-
ing temperature. Since flow is diverted either to by-pass or heat
exchanger, failure of an element would cause no change in pressure
drop.
The content s of the element s (9) ha s a n a lmost infinite force w hen
heated and is positively sealed. When the elements are heated, this
force is tra nsmitt ed to the piston th us moving the sliding va lve towa rds
t he sea t (11) t o th e by-pa ss closed posit ion. This force is opposed by a
high spring force, w hich moves the sliding valve to the hea t excha nger
closed position w hen th e element s a re cooled. The high force ava ila ble
on heating is the basis of the fail safe feature in which failure of the
element w ould ca use th e engine t o run cold.
The HT th ermosta tic va lve in ma in engine insta lla tions are provided
w ith a possibility for ma nua l override.
A
From engine
B
By-pass
A
From engine
C
To cooler
WARM ENGINE COLD ENGINE
Fig 19-5
3219669250
Cooling Water System, V-engines 34SG-9501