Sandpiper PB 1/4 User Manual download pdf (Page 7)

pb025nmdl3sm-rev0614 Page 5

PRINCIPLE OF PUMP OPERATION

This ball type check valve pump is

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 centres 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 dis-

charged 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 dia-

phragm 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 ow 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

ttings 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 ow.

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 exible hose not less than 1/2"

(13mm) in diameter between the pump

and the piping to reduce strain to the

piping. The weight of the air supply line,

regulators and lters 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 pres-

sure 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 pre-

ferred 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 Warren

Rupp) 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 ow as desired. If opening

the valve increases cycling rate, but does

not increase the rate of ow, cavitation

has occurred. The valve should be closed

slightly to obtain the most efcient air ow

to pump ow 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 ushed

after each use to prevent damage.

(Product remaining in the pump be-

tween 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.

Figure 1

Figure 2

Figure 3

CHECK VALVE SERVICING

Need for inspection or service is

usually indicated by poor priming,

unstable cycling, reduced performance

or the pump's cycling but not pumping.

Remove the sixteen machine screws

securing the manifold assemblies to the

outer chambers. Inspect the surfaces

of both check valve and seat for wear

or damage that could prevent proper

sealing. If pump is to prime properly,

valves must seat air tight.

DIAPHRAGM SERVICING

Remove the two V-Band clamps

securing the outer chambers to the

intermediate housing. Remove the

diaphragm assembly (outer plate,

diaphragm, inner plate) by turning the

assembly counterclockwise using a 1/2"

(1.27 cm) wrench on the outer plate

lugs. (If a socket is used, it must be a six

point socket.) The interior components

consisting of the shaft seal and pilot

valve assembly are now accessible for

service.

Procedures for reassembling the

diaphragms are the reverse of the above.

Install the diaphragm with the natural

bulge outward.

Install the outer diaphragm plate on

the outside of the diaphragm and make

certain that the large radius side of the

inner plate is toward the diaphragm.

Tighten the outer diaphragm plate to

approximately 30 in./lbs. (3.39 Newton

meters).

Torque while allowing the diaphragm

to turn freely with plates. Use a wrench

on the outer diaphragm plate of the

Figure 4

opposite side to keep rod from rotating. If

the opposite chamber is assembled, the

rod need not be held.

EXTERNALLY SERVICEABLE MAIN AIR

DISTRIBUTION VALVE

To service the main air distribution,

rst shut-off and disconnect the air supply

to the pump. Remove the four long hex cap

screws and hex nuts (on opposite side of

pump) which fasten the main air valve

body (item 1), gaskets (item 8 and 11),

mufer (item 14), and caps (item 6 and

15) to the pump.

Once the main air valve body is off the

pump remove the retaining rings (items 7)

that hold the end caps in place. Remove

the end caps (items 6) to inspect the spool

and sleeve. Remove the main air spool

(part of item 2) and inspect for damage or

wear. Inspect the inside diameter of the

main air valve (item 2) for dirt, scratches,

or other contaminants. Remove and

replace the sleeve if needed. When

reinstalling the sleeve, apply a light

coating of grease to the six o-rings

(item 3) before inserting the sleeve into

the main air valve body. Align the holes

in the sleeve with the slots in main

valve body, making sure the sleeve is

centered in the bore. Clean the main

air valve spool, lightly grease the o-

rings, and insert into the sleeve flush

to one end. Reinstall the end caps and

retaining rings. The main air valve body

is now ready to put back on the pump.

Assemble the air inlet cap (item 9),

valve body gasket (item 8), to the main

air valve body (making sure the ve rect-

angular slots face the air inlet cap), and

the intermediate gasket onto the four hex

capscrews and install onto the pump. Slide

the mufer (item 14) and the exhaust cap

(item 15) over the capscrews. Re-install

the washers (item 10) and hex nuts (items

16) onto the four hex capscrews and

torque to 30 in/lbs. (3.39 Newton meters).

SERVICING THE PILOT VALVE

To remove the pilot valve spool (item

23) rst remove the end o-ring (item 24)

from one end of spool. Slide the spool

out of the sleeve and inspect the five

remaining o-rings (items 24) for damage

or wear. If necessary, replace damaged

o-rings. Inspect the inner diameter of pilot

valve sleeve (item 20) for scratches, dirt,

or other contaminants. Replace the sleeve

if necessary. To remove the sleeve rst

remove the retaining ring from one end.

When installing a pilot valve sleeve rst

lightly grease the six o-rings (items 21).

Insert the sleeve into the chamfered end

of bore on the intermediate bracket (item

13). Push the sleeve in until the shoulder

is ush to intermediate bracket surface

and install the retaining ring (item 22).

To install the pilot valve spool rst lightly

grease the four interior o-rings and insert

into the pilot valve sleeve. After insert-

ing the spool into the sleeve install the

remaining loose o-rings onto spool.

SERVICING DIAPHRAGM ROD SEALS

To service the rod seals (item 18)

first remove pilot valve, then remove

the inserts on each of the intermediate

brackets (item 17) by prying them

out with a small at screwdriver. After

removing the inserts take the K-R rod

seals out of the inserts and replace.

When reinstalling the seals, make sure

the open side of the seals face into the

counterbore in the inserts. To install the

inserts into intermediate bracket, simply

press the insert into the counterbore in

each of the intermediate bracket, making

sure that the closed side of insert faces out.

The inserts should be ush to the surface

of the intermediate bracket or slightly

below the surface when fully installed.

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Sandpiper PB 1/4 User Manual Page 7

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