TM 9-4940-556-14&P
3.8.6 Mode switch S-4 is to select either the pressure wash or steam
mode of operation. This switch energizes and deenergizes, solenoid
valve SV-3 for water bypass and changes fuel pump outlet pressure.
3.8.7 Blow down switch S-5 will be used in conjunction with valve
V-5 for blow down operation. This switch enables the operator to
energize the burner circuit.
3.9 DESCRIPTION OF OPERATION AND COMPONENTS-WATER SYSTEM - REF.DRAWING JP7221
3.9.1 (Reference drawing JP7205-A) Water enters the unit thru a hose
ferrule into the float tank. Water is drawn from the float tank through
a strainer in the float tank, then thru a float tank SHUT-OFF valve and
a "WYE" strainer to the pump where its pressure is increased substantially.
3.9.2 (Reference drawing JP7212) The pump is equipped with an accumulator,
a device which absorbs hydraulic pulsations in the water system. The
hose which connects the pump outlet with the coil inlet fittings is
an alleviator hose - a. special hose which also absorbs hydraulic pulsations.
On the RI-2400 a solenoid valve is used on the left output side of
the pump to return a fixed volume of water back to the float tank. The
volume of water "dumped" in this fashion is determined by an orifice
placed in the return line. The switch used to control this dumping
is called the MODE SWITCH (S-4). In its pressure position, it permits
the full pumped volume of water to pass through the COIL: when this
switch is on the STEAM position, a measured volume of water returns
to the float tank thus reducing the volume of water pumped thru
the heating coil.
3.9.3 (Reference drawing JP7219) The discharge line from the pump
connects to the inlet of the heating coil. Because the RI-2400 is
equipped with nozzle control, an unloader, a pressure actuated valve,
is also connected to the outlet of the pump. The unloader diverts
the water from the pump back to the float tank when the cleaning gun
is closed.
3.9.4 At the coil inlet there is a pressure drain/relief valve which will
protect the coil and pump from a blocked cleaning gun. A coil inlet
pressure gauge is also connected to the inlet fittings assembly.
3.9.5 Water passes thru the coil, where it is heated, and into the
coil outlet fittings assembly which includes an outlet pressure gauge,
outlet temperature gauge and the sensing bulb for the temperature
control (TC-1).
3.9.6 The hose and cleaning gun are attached to the coil outlet fitting
assembly. The cleaning gun can be fitted with either a pressure wash
tip or a steam nozzle and orifice assembly. The tip and orifice restrict
the flow of water thru the system and cause the unit to operate at
the correct pressure with the appropriate temperature rise. The cleaning
gun handle is also equipped with a valve which will turn the cleaning
spray on or off.
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