31
PUMP
The pump must have enough capacity to satisfy the
agitation, servo and flowmeter sections of the plumbing. To
determine if your pump is large enough you must add up
the gallons per minute of all three sections. The following
example will take you through the steps involved.
EXAMPLE
Let’s say our example sprayer has a 300-gallon tank
with a Spraying Systems 6290 SC-8 Jet Agitator. The
agitator uses 10.2 GPM at 40 PSI.
The sprayer has a 40’, three-section boom. Each section
is 160” with four tips at 40” for a total of 12 tips. We
plan to put on a 25 GPA at 5 MPH and in some areas
of the fields we may want to use the Delta feature and
increase our rate to 30 GPA and in other areas decrease
to 15 GPA. After checking the tip charts we find that a
TK-5 Floodjet has a range of 14.9 to 30 GPA at 5 MPH.
According to the charts, to get 30 GPA at 5 MPH with a
TK-5, the pressure must be 40 PSI. At 40 PSI a TK-5 will
spray 1.0 GPM. So, 12 tips at 1.0 GPM each is a total of
12 GPM.
Now let’s add everything together.
Agitation
10.2
Spray tips
12.0
Servo
5.0
27.2 Total GPM
The above addition shows that the system needs 27.2
GPM at 40 PSI. If we add a 10% margin (27.2 x 1 = 2.72
and 27.2 = 29.92), we have about 30 GPM. To be sure
we have enough volume, the pump should be able to
deliver 30 GPM or more at 40 PSI.
Valve Purpose and Adjustments
TANK SHUT-OFF VALVE
The tank shut-off valve is for convenience only. It allows
you to work on the plumbing without draining the tank. It
should always be fully open during operation.
AGITATION SHUT-OFF VALVE
The agitation shut-off valve is mostly for convenience. It
allows you to work on the plumbing without draining the
tank. It should normally be fully open during operation.
PRESSURE RELIEF VALVE
The pressure relief valve is used to avoid excessive pressure
when the booms are turned off. Start with the handle
screwed mostly out. Slowly bring pump up to operating
RPM (make sure pressure does not go too high). Put the
MT-3405F™ II in MAN and turn boom on. Hold adjust switch
to “+” for about 30 seconds to fully close servo valve. Turn
booms OFF. Now slowly screw handle in until maximum
desired pressure is reached. Lock handle in place with
locking nut or collar.
NOTE: Spraying Systems 144H DirectoValve has a
maximum pressure rating of 100 PSI (7 bar).
RANGE ADJUST VALVE
The range adjust valve is required when the pump is much
larger than necessary. When the range valve is opened,
some of the liquid will be bypassed around the pump to
avoid “overloading” the rest of the system. The setting of
the range adjust valve is determined by the throttle valve.
Start with the range valve fully closed and perform the
Pre-field System Checkout on pages 39-40.
If the throttle
valve needs to be more than two thirds closed, open the
Range valve slightly and perform the Pre-field System
Checkout again.
THROTTLE VALVE
(Bypass Plumbing)
The throttle valve limits your high end to maximize servo
performance.
Start with throttle valve fully open and
perform the Pre-field System Checkout on page 39-40.
EXAMPLE
With the throttle fully open and servo fully closed, you
may be able to get 50 GPA at 5 MPH when you only
want 25 GPA. If you were to simply open the servo you
may be able to get down to 25 GPA, but if your speed
should drop to 3 MPH, the servo can’t open any farther
and won’t be able to maintain 25 GPA. Therefore, if you
leave the servo closed and close the throttle until your
high end has dropped from 50 GPA to about 30 GPA,
the servo has a greater operating range.
The throttle valve pictured in the system diagram is a
needle valve (Spraying Systems Type 12690 or 12795).
A ball valve may be used but is more difficult to adjust
and keep adjusted. Do not install a pressure regulator
or relief as a throttle valve.
If the throttle valve is closed too much, PSI may
fluctuate greatly in AUTO.
RELIEF SOLENOID VALVE
The optional relief solenoid will ensure enough bypass to
avoid excessive pressure when the boom valves are turned
OFF.
See pages 21-22.
Plumbing Guidelines
(cont)
General
(cont)
