MEGA Corp. MSC-OPS-1 - Manual (Page 22)

MSC/MST-OPS-1
31 Dec 2013
SECTION 2
System Description
2-13
HYDRAULIC SPRAY HEAD
A two piece aluminum valve
body, hydraulic cylinder and
adjustable ring mounted to a
water supply header pipe. The
upper portion of the valve body
contains a hydraulic cylinder
that receives hydraulic pressure
from the system solenoid control box as commanded
by the cab control switch. When the hydraulic
cylinder on the upper portion of the valve body is
pressurized the cylinder extends to contact the guide
disk and seal the opening on the lower portion of the
valve and stop water flow. When the cab control
system is OFF and the water pump is OFF the upper
valve body incorporates a spring to apply pressure to
the guide disk to seal the opening on the lower
portion of the valve and stop flow. When the spray
head switch is turned on hydraulic pressure retracts
the hydraulic cylinder and pressurized water from the
header pipe will unseat the guide disk and water will
flow from the lower portion of valve.
Spray Head Adjustable Rings
The adjustable ring is used to control fan width and
water flow. The ring may be loosened and rotated to
expose more or less of the lower valve opening to
control water fan width from 15° to 90°. The ring also
may be used rotated to a 1/4” or 3/8” slot (as shown
below) to increase or decrease overall water flow. The
greater the opening, the greater the water flow.
SOLENOID CONTROL BOX
The control box assembly is mounted to the forward
bulkhead or the rear of the gooseneck of the MSC/
MST. The assembly contains pneumatic or hydraulic
solenoid valves that direct pneumatic or hydraulic
pressure to the spray head as commanded by the cab
control box. The solenoids receive pneumatic
pressure from the vehicle or hydraulic pressure from
water pump oil circuit and 24 VDC power from the
cab control box.
DUMP BAR
A spray bar that contains several rows of 3/8” drain
holes to dispense water. A hydraulically operated BFV
controls the water supply to the dump bar. The BFV is
controlled electrically from the cab control box and is
actuated by a hydraulic cylinder. The actuators
receive hydraulic pressure from the solenoid control
box assembly. Dump bars can be either gravity or
pressure fed.
HOSE REEL
A reel assembly that is
located on the bottom aft
end of the water tank fitted
with a 1” or 1.5” diameter
reinforced rubber hose and
a fire fighting style nozzle.
The hose reel assembly
receives pressurized water
from the pressurized
manifold on the back of the tank to operate.
1/4” Opening
3/8” Opening
Pneumatic Hydraulic