520-202-000 9/03 Model S20 Non-Metallic Design Level 2 Page 8
PRINCIPLE OF PUMP OPERATION
This ball type check valve pump is
poweredbycompressedair and isa1:1
ratio design. The inner side of one
diaphragm chamber is alternately
pressurized while simultaneously
exhaustingtheotherinnerchamber.This
causes the diaphragms, which are
connected by a common rod secured
by plates to the centers of the
diaphragms,tomoveinareciprocating
action.(Asonediaphragm performs the
discharge stroke the other diaphragm
is pulled to perform the suction stroke
in the opposite chamber.) Air pressure
is applied over the entire inner surface
of the diaphragm while liquid is
dischargedfromtheopposite sideofthe
diaphragm.Thediaphragmoperatesin
a balanced condition during the
dischargestrokewhichallows thepump
tobeoperatedatdischargeheadsover
200 feet (61 meters) of water.
For maximum diaphragm life, keep
the pump as close to the liquid being
pumped as possible. Positive suction
headinexcessof 10feetofliquid (3.048
meters) may require a back pressure
regulating device to maximize
diaphragmlife.
Alternate pressurizing and
exhausting of the diaphragm chamber
isperformedbyanexternallymounted,
pilot operated, four way spool type air
distributionvalve.When thespoolshifts
to one end of the valve body, inlet
pressure is applied to one diaphragm
chamber and the other diaphragm
chamber exhausts. When the spool
shifts to the opposite end of the valve
body, the pressure to the chambers is
reversed.Theair distributionvalvespool
is moved by a internal pilot valve which
alternately pressurizes one end of the
air distribution valve spool while
exhaustingthe otherend.Thepilotvalve
is shifted at each end of the diaphragm
stroke when a actuator plunger is
contacted by the diaphragm plate.This
actuatorplungerthenpushestheendof
the pilot valve spool into position to
activate the air distribution valve.
The chambers are connected with
manifolds with a suction and discharge
check valve for each chamber,
maintainingflowinone directionthrough
thepump.
INSTALLATIONANDSTART-UP
Locate the pump as close to the
productbeingpumped aspossible.Keep
the suction line length and number of
fittingstoaminimum.Donotreducethe
suctionlinediameter.
Forinstallations of rigidpiping,short
sections of flexible hose should be
installed between the pump and the
piping. The flexible hose reduces
vibration and strain to the pumping
system. A surge suppressor is
recommended to further reduce
pulsation in flow.
AIR SUPPLY
Air supply pressure cannot exceed
100 psi (7 bar). Connect the pump air
inlet to an air supply of sufficient
capacity and pressure required for
desired performance. When the air
supply line is solid piping, use a short
length of flexible hose not less than ½"
(13mm) in diameter between the pump
and the piping to reduce strain to the
piping.Theweightof the air supply line,
regulatorsandfiltersmustbe supported
by some means other than the air inlet
cap. Failure to provide support for the
piping may result in damage to the
pump. A pressure regulating valve
should be installed to insure air supply
pressuredoesnotexceedrecommended
limits.
AIRVALVE LUBRICATION
Theairdistribution valveandthepilot
valvearedesignedtooperateWITHOUT
lubrication. This is the preferred mode
ofoperation.Theremaybeinstancesof
personal preference or poor quality air
supplies when lubrication of the
compressed air supply is required.The
pump air system will operate with
properly lubricated compressed air
supply. Proper lubrication requires the
useofanairlinelubricator(availablefrom
WarrenRupp)setto deliveronedropof
SAE 10 non-detergent oil for every 20
SCFM (9.4 liters/sec.) of air the pump
consumes at the point of operation.
Consult the pump’s published
Performance Curvetodeterminethis.
AIR LINE MOISTURE
Water in the compressed air supply
can create problems such as icing or
freezing of the exhaust air, causing the
pump to cycle erratically or stop
operating.Waterintheair supply can be
reducedbyusinga point-of-useairdryer
to supplement the user’s air drying
equipment.This device removes water
from the compressed air supply and
alleviatestheicingor freezing problems.
AIR INLET AND PRIMING
To start the pump,opentheairvalve
approximately ½" to ¾" turn. After the
pump primes, the air valve can be
opened to increase air flow as desired.
If opening the valve increases cycling
rate, but does not increase the rate of
flow, cavitation has occurred.The valve
should be closed slightly to obtain the
mostefficientairflowto pump flowratio.
BETWEEN USES
Whenthepumpisused for materials
that tend to settle out or solidify when
notinmotion,thepumpshouldbeflushed
after each use to prevent damage.
(Productremainingin thepumpbetween
usescoulddryoutorsettleout.Thiscould
causeproblemswiththediaphragmsand
check valves at restart.) In freezing
temperatures the pump must be
completely drained between uses in all
cases.
