SANDPIPER M15 Non-Metallic - Manual (Page 8)

m15nmdl3sm-rev0713 Model M15 Non-Metallic Page 6
PRINCIPLE OF PUMP OPERATION
This ball type check valve pump
is powered by compressed air and is
a 1:1 ratio design. The inner side of
one diaphragm chamber is alternately
pressurized while simultaneously
exhausting the other inner chamber.
This causes the diaphragms, which are
connected by a common rod secured by
plates to the centers of the diaphragms,
to move in a reciprocating action. (As
one diaphragm 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 discharged
from the opposite side of the diaphragm.
The diaphragm operates in a balanced
condition during the discharge stroke
which allows the pump to be operated
at discharge heads over 200 feet (61
meters) of water.
For maximum diaphragm life, keep
the pump as close to the liquid being
pumped as possible. Positive suction
head in excess of 10 feet of liquid
(3.048 meters) may require a back
pressure regulating device to maximize
diaphragm life.
Alternate pressurizing and
exhausting of the diaphragm chamber
is performed by an externally mounted,
pilot operated, four way spool type
air distribution valve. When the spool
shifts 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. The air distribution valve
spool is moved by a internal pilot valve
which alternately pressurizes one end
of the air distribution valve spool while
exhausting the other end. The pilot valve
is shifted at each end of the diaphragm
stroke when a actuator plunger is
contacted by the diaphragm plate. This
actuator plunger then pushes the end
of 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,
maintaining flow in one direction
through the pump.
INSTALLATION AND START-UP
Locate the pump as close to the
product being pumped as possible.
Keep the suction line length and
number of fittings to a minimum. Do not
reduce the suction line diameter.
For installations of rigid piping,
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. The weight of the air supply line,
regulators and filters must be 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 pressure does not exceed
recommended limits.
AIR VALVE LUBRICATION
The air distribution valve and the
pilot valve are designed to operate
WITHOUT lubrication. This is the
preferred mode of operation. There may
be instances of 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 use of an air line
lubricator (available from MARATHON)
set to deliver one drop of 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 Curve
to determine this.
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. Water in the air supply can
be reduced by using a point-of-use
air dryer to supplement the user’s air
drying equipment. This device removes
water from the compressed air supply
and alleviates the icing or freezing
problems.
AIR INLET AND PRIMING
To start the pump, open the air valve
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
most efficient air flow to pump flow ratio.
BETWEEN USES
When the pump is used for materials
that tend to settle out or solidify when
not in motion, the pump should be
flushed after each use to prevent
damage. (Product remaining in the
pump between uses could dry out or
settle out. This could cause problems
with the diaphragms and check valves
at restart.) In freezing temperatures
the pump must be completely drained
between uses in all cases.