Selecting the Right Pump

Selecting the Right Pump
Selecting the Right Pump
Because the pump is literally the “heart of the liquid
system” on a sprayer, careful consideration must be
made in selecting the right pump. Seldom is there only
one pump that will do the job. To make a wise choice, you
will need to know about pump types, how the pump is to
be driven and the flow and pressure requirements for
your specific spraying system and application.
To ensure you can closely match the pump to your
needs, Hypro manufactures six types of pumps: roller,
centrifugal, transfer, diaphragm, turbine and piston
Centrifugal and Transfer Pumps (non-positive
“Positive displacement” vs. “Non-positive displacement”
Hypro’s long line of pumps can be divided into two
general categories: “positive displacement” and “nonpositive displacement.” Roller, diaphragm and piston
pumps are positive displacement. That is, the flow from
the pump is directly proportional to the pump speed. This
positive flow is why all positive displacement pump hookups must include a relief valve and bypass line between
the pump outlet and the nozzle shut-off valve.
Centrifugal and turbine pumps are non-positive
displacement. In these pumps, a rotating impeller creates
a centrifugal force that feeds the liquid through the
system instead of capturing and discharging a fixed
volume “per stroke” as rollers, pistons or diaphragms
would do. Therefore, if the outlet is closed, the impeller
simply continues to rotate harmlessly. That is why special
relief valves are not required in centrifugal pump
In centrifugal pumps, spray solution enters through the
center of a rotating impeller that’s driven at speeds up to
6000 RPM. Spray solution is forced to the outer edge of
the housing. This centrifugal force is what delivers the
liquid to the nozzle. Traditionally thought of as low to
medium pressure pumps, Hypro’s centrifugal pumps can
deliver from 0-190 psi and flow rates up to 370 gpm.
Because centrifugals have minimum surfaces to wear
and no valves, they are very durable, easy to maintain
and well suited for pumping abrasive and corrosive
Because centrifugal pumps operate at higher speeds, the
PTO speed must be increased through a speedup gear
drive, belt/pulley drive, gas engine drive, or a high-speed
hydraulic motor. (Hypro has models specifically designed
for each of these applications).
The broad, versatile line includes models with rugged
housings of cast iron, polypropylene and stainless steel
that stand up to the wide variety of agricultural chemicals.
DC motor, diaphragm pumps are used for a variety of
agricultural, horticultural and pest control spraying
Roller Pumps (positive displacement)
Hypro roller pumps are the number one all-around choice
by farmers throughout the world. The rollers (from 4 to 8,
depending on the model) revolve inside the pump
housing to force the spray solution through the outlet to
the nozzle. Roller pumps have a low initial cost and are
extremely versatile. They operate efficiently at PTO
speeds of 540 and 1000 rpm and have a wide pressure
range of up to 300 psi and flow rates of 2 to 74 gpm.
Roller pumps are self priming and easily adapt to PTO or
gas engine drives. Specific seal, roller and casting
materials can be selected for compatibility with certain
herbicides, pesticides, fungicides and fertilizers.
Piston Pumps (positive displacement)
Piston pumps are not unlike an engine. That is, they have
a shaft, pistons and “intake” and “exhaust” valves. On the
down-stroke, the inlet valve opens, filling the chamber
with solution. On the up-stroke, the outlet valve opens,
and the piston forces the solution to the nozzle. Piston
pumps deliver relatively low flow rate (up to 10 gpm) at
high pressure (up to 400 psi). The replaceable piston
cups can be of leather, fabric or Buna-N rubber,
depending on the type of solution to be sprayed. They
can be driven by 540 rpm PTO, gas engine or electric
motor. Their low volume/high pressure capability permits
use in general spraying as well as task-oriented
applications such as spraying fence rows and ditches,
and hydrostatic testing.
Hypro Pumps Identification Coding
Hypro uses serialized labeling to enable users to
precisely identify the pump when ordering parts or
requesting warranty service. Following is an example.
First line: Model Number
Second line: Serial Number
First & second digit:
year (03=2003)
Diaphragm Pumps (positive displacement)
Because of their design, diaphragm pumps provide
excellent handling of abrasive and corrosive materials.
The pumping cylinders (from 2 to 6) are separated from
the piston chambers (Hypro’s are oil-filled) by a synthetic
diaphragm. This keeps the spray solution from contacting
and corroding the internal pump components.
Third through fifth digits:
consecutive day of the year
the pump was manufactured.
Sixth digit: shift the pump
was built on.
Seventh through tenth digits:
consecutive pump number
built on the shift.
Diaphragm pumps are compact, self-priming and produce
medium-to-high pressures (275 to 725 psi) with flow rates
of 3.5 to 66 gpm. Driven by 540 rpm PTO, gas engine or
Selecting the Right Pump
Pump Drives
How a pump is to be driven is often a primary
consideration in selecting the proper type of pump. If the
power source has already been determined, the following
chart may be of further help in selecting the type of
Hypro pump that is best suited to your needs.
You can use these pump types:
If your power source is:
direct coupled:
through gear drive:
through belt/pulley:
direct coupled:
through gear drive:
through belt/pulley:
540 rpm PTO
1000 rpm PTO
Hydraulic Motor
12 Volt DC Motor
Gas Engine
Electric Motor
direct coupled:
through gear reduction:
through belt/pulley:
direct coupled:
through belt/pulley:
and Transfer
Pump shaft rotation
With many pumps, you need to specify which direction
the shaft rotates… either clockwise (CW) or counterclockwise (CCW). Hypro’s rules on shaft rotation are as
PTO Shaft:
clockwise (CW) rotation
Rule #1 “Eyes on the end”
Always view the rotation when you are facing the end of
the drive shaft. If it turns clockwise, it is a clockwise shaft.
Always use this rule for determining rotation of the pump
shaft and for the power source shaft (PTO, for example).
Once you have determined the rotation of the power
source shaft, remember Hypro rule #2:
Rule #2 “Opposites attract”
A clockwise (CW) rotating PTO shaft will require a
counterclockwise (CCW) rotating pump shaft, and vice
versa. All shaft rotation references in this catalog are
based on these two rules.
Electric Motor:
(CCW) rotation
Gas Engine:
(CCW) rotation
Determining Pump Flow and Pressure Requirements
Every pumping task has an optimum volume and
pressure requirement. Determining that optimum (and
selecting the pump that delivers it) is key to an efficient
and economical spraying system operation.
Pressure requirements for agricultural pumps are
dependent on both the material to be applied and
application targets. Soil-applied herbicides generally
require a relatively low pressure pump rating of 30-60 psi
with foliar-applied herbicides at the top end of that range
and slightly higher. Insecticides and fungicides require
higher pressure ratings of 100 to 500 psi. Pressure must
be sufficient, in the case of heavy foliage field crops and
orchard crops, to penetrate the leaf cover. In the case of
orchard crops, pressure must also be sufficient to carry
material up and over as well as into the canopy.
A number of factors must be considered to properly
determine the total flow you will need from your pump.
They include:
• Type of spray operation (broadcast, banding, lowlevel, etc.)
• The chemical’s application rate, ground speed, boom
width, hose length, tank agitation, etc.
The spray task is the first consideration in determining
flow rate and pressure needs. The following formulas and
calculations may help.
Reducing agitation flow requirements
Agitation flow requirements can be reduced by using jet
agitation in the tank. Jet agitators use a venturi design
to multiply agitation output. Depending on the jet agitator
model and pressure, one gallon per minute input can
provide two to ten gallons per minute agitation output.
If your sprayer is equipped with a jet agitator, consult the
operator's manual or documentation to find the output
to input ratio and adjust your flow required for agitation
For example: If you calculate a requirement of 63 gpm of
agitation and your jet agitator requires 3 to 1 output to
input ratio, your pump would only need 1/3 of 63 gpm,
or 21 gpm.
Agitation Flow with Jet Agitation = required gpm (input/output)
Factor in an “Excess Flow” Requirement
It is wise to have some excess flow capacity so you will
not end up with an undersized pump because actual
operation conditions may cause changes in spray system
performance (such as normal pump wear, operating at
less than rated speeds, etc.). Hypro recommends you
add an additional 20% to your calculated total pump flow
requirement to compensate for these variables. Plumbing
systems have a number of restrictions that will result in a
pressure drop from the pump to the actual spray point.
These must be taken into account and minimized.
Calculating agitation requirements
The pump must produce enough flow for both the
application rate and tank agitation requirements. Too little
agitation will not keep the solution in proper suspension
and too much agitation may cause foaming. Here are rule
of thumb formulas for calculating how much additional
pump flow you will need for agitation.
Tank volume (gallons) x .05 = total agitation in gpm
Wettable Powders and Flowables:
Tank volume (gallons) x .125 = total agitation in gpm
EXAMPLE: If you will be spraying a wettable powder
from a 100-gallon tank, proper agitation will require 12.5
gpm additional flow from the pump.
Determining Pump Flow and Pressure Requirements
For total pump flow requirement (banding), calculate:
Flow required for boom:
Flow required for agitation:
Excess flow requirement:
Calculating pump flow for broadcast boom sprayers
Chemical application is measured in gallons per acre
(gpa), whereas pump flow is stated in gallons per minute
(gpm). To calculate the pump flow gpm required by a
broadcast boom sprayer, multiply the gpa application rate
(from the chemical label, usually 10-20 gpa) by the
sprayer ground speed (5-10 mph). Multiply the sum by
the boom width on your sprayer (in feet). Then, divide
that number by 495. As a formula, it is written like this:
Flow required
for boom (gpm) = gpa x mph x boom width (ft.)
The result will be the pump flow required to deliver the
proper application rate at the boom’s nozzles. Then
calculate your total pump flow requirement (broadcast):
Calculating pump flow for hand gun spraying
For low-level spraying with a hand gun, such as for lawn
and turf care, professional applicators typically “walk” the
lawn at about 1,000 sq. ft. per minute. That means the
“gpm” rate of the hand gun will generally be the same as
“gallons per 1,000 sq. ft.” To determine your total pump
flow requirement:
Flow required for gun/nozzle:
Flow required for boom:
Flow required for agitation:
Excess flow requirement:
Flow required for agitation:
Excess flow requirement:
______ gallons per
1,0002 (same
as gpm)
______ gpm
______ gpm
______ gpm
Use this same method for calculating the pump flow
requirement for high pressure spraying, such as trees.
Even though the application “rate” is usually a visual
saturation of the tree, the known gpm factor will be the
hand gun nozzle output, which is the rate you use for the
Calculating pump flow for banding sprayers
First, multiply the band width (in inches) by the number of
rows to determine the total width (w). Then, multiply the
application rate (gpa from the chemical label) by the
ground speed (mph). Multiply that result by the total width
(w) calculated earlier, then divide the result by 5940.
Here’s how the formula appears:
Flow required
for nozzles (gpm) = gpa x mph x w
Recommended Pump Placement
Proper torque
arm mounting
Location of PTO driven pumps and pump drive units may
have a significant effect on pump life. Mounting the pump
directly to the PTO is always a good choice. Even though
installation is relatively easy, use caution to ensure the
shaft does not get bent or damaged. Always use a
quality, properly secured coupler and provide adequate
support for the pump itself in order to withstand the
extreme bouncing and vibration the system must endure.
PTO mounting shields should always be used for
maximum safety and protection.
If direct PTO mounting is not convenient or desired, then
mount the pump in a convenient position on the pullbehind sprayer and connect it to the tractor PTO with a
“tumble rod” power shaft. Exercise caution when using
this approach to ensure: (1) the tumble rod is level; (2)
the hitch pin is the center-point; and (3) turn angles
greater than 45° can be avoided. Failure to follow these
three points may cause “power shocks” within the pump
and drive units and increase wear on seals, gears and, in
the case of diaphragm pumps, the diaphragms
Correct Equidistant
Tumble Rod Installation
X and Y are equal, which
maintains equal u-joint angles
and prevents fluctuations.
Incorrect Tumble
Rod Installation
X and Y are not equal, creating
unequal u-joint angles which
can result in RPM fluctuations
and increased wear on the
u-joints and pump.
The best tumble rod installation occurs when the
distance from the PTO U-joint to the hitch is equal to the
distance from the hitch to the pump U-joint. For 540 RPM
PTO shafts, the distance from the hitch pin to the pump
shaft should be 14 inches. For 1000 RPM 13⁄8" PTO
shafts, the distance is 16 inches. For 1000 RPM 13⁄4" PTO
shafts, the distance is 20 inches. Instances where equal
distances are not possible, a “constant velocity” shaft
should be used.
Power shocks occur when the PTO shaft knuckle and the
universal joint at the pump end of the tumble rod turn
faster on the inside of the turning angle than on the
outside. To prevent these vibrations, the angle of the
tumble rod to the tractor PTO shaft and the angle of the
tumble rod at the pump shaft should be as close to equal
as possible. This will cancel out the fluctuations.
System Hook-Ups
Roller, Diaphragm and Turbine Pumps
Tank Lid
Ball Valves
Jet Agitator
Agitation Line
Spray Contol
Boom Valve
Control Valve
Compact Jet Turret
Nozzle Body
Hypro carries all parts labeled above. Please contact your local Hypro dealer
or call 1-800-424-9776 for more information.
System Hook-Ups
Centrifugal Pumps
Tank Lid
Vent Line
Ball Valves
Jet Agitator
Spray Control
Boom Valve
Pump Control
Compact Jet Turret
Nozzle Body
Hypro carries all parts labeled above. Please contact your local Hypro dealer
or call 1-800-424-9776 for more information.
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