19.1.2 HT circuit
The H T circuit cools t he cylinders, cylinder h ea ds a nd th e tur bocha rg-
ers.
A centr ifuga l pump (9) pumps the wa ter t hrough t he HT circuit. From
the pump the water flows to the distributing duct, cast in the engine
block (in V-engines th e wa ter is dist ribut ed to the dist ribut ing ducts of
each cylinder bank t hrough ducts ca st int o the pump cover a t t he free
end of the engine). From th e distributing ducts the w a ter flow s to th e
cylinder w a ter ja ckets, furt her t hrough connection pieces to the cylin-
der hea ds w here it is forced by t he intermediat e deck to flow a long t he
flame plate, around the valves to the exhaust valve seats, efficiently
cooling all these components. From the cylinder head the water flows
through a connection piece to the collecting pipe, further to the tem-
pera tur e cont rol va lve ma inta ining the tempera ture a t t he right level.
P a ra llel to the flow t o the cylinders, par t of the w a ter flow s to th e
turbochargers.
19.1.3 LT circuit
The LT circuit consists of a charge air cooler (7) and a lube oil cooler
(15), not m ount ed on th e engine, thr ough w hich a pump (8), identical
to th e HT pump, pumps the w a ter. The circuit tempera tu re is contr olled
by a temperature control valve (10), not mounted on the engine. The
necessary cooling is gained from the central cooler (14). The system
outside the engine ca n va ry from one insta llat ion t o another.
19.1.4 Venting and pressure control
The collecting pipes from th e cylinder a nd tu rbocha rger cooling sy stem
a re conn ected t o a box (2) for vent ing of the syst em. From t his box the
vent pipe leads to the expansion tank (1) from which the expansion
pipe is connected to the inlet pipe of the pumps (8 and 9). A static
pressure of 0.7...1.5 bar is requ ired before t he pumps. I f th e expa nsion
ta nk can not be loca ted h igh enough t o provide th is pressure, the system
is t o be pressurized.
19.1.5 Preheating
For preheating of the circuit, a heater circuit with the pump (13) and
heater (12) are connected in the HT circuit before the engine. The
non-return valves in the circuit force the water to flow in the right
direction.
B efore sta rt , the HT circuit is hea ted up to 70...80°C by a separa te
heater.
Cooling Water System, V-engines
34SG-9501