12
WILDEN PUMP & ENGINEERING CO.
SECTION 7C
OPERATING PRINCIPLES BEHIND
ACCU-FLO™ PUMPS
In Accu-Flo™ pump models, the standard air valve is replaced
with a two position, four-way solenoid valve that has a single
operator and spring return. The valve is internally air piloted for
longer coil and operator life.
When the solenoid is unpowered, one air chamber is pressur-
ized with air, while the opposite chamber is exhausted. When
electric power is applied, the solenoid shifts, and the pressur-
ized air chamber is exhausted while the opposite chamber is
pressurized. By alternately applying and removing power, the
solenoid-operated pump runs like a standard Wilden pump.
The speed of the pump is controlled electrically. Since each
stroke is controlled by an electrical signal, the pump is ideal for
batching and other electrically controlled dispensing applications.
Although the speed of the pump is controlled electrically, the air
pressure is important. Air pressure displaces the fluid, and if the
pressure is insufficient to complete the physical stroke before an
electronic impulse signals the pump to shift, the stroke will not
be completed, and the displacement per stroke will be reduced.
This does not harm the unit in any way, but it may cause inac-
curacy when attempting to batch specific quantities with high
precision if this effect is not taken into account.
There are three coil voltage options available. One coil allows for
24V DC operation. The second coil option allows for operation
with either 12V DC or 24V AC at 60 Hz and the third coil option
allows for 110V AC operation.
SECTION 7D
INSTALLATION – A4 PLASTIC
ACCU-FLO™ PUMPS
Before installing your A4 Accu-Flo™ pump, review Section 7A
for general installation suggestions including Location, Access,
Air Supply, Elevation, and Piping.
The Accu-Flo™ Model A4 has a 3.81 cm (1
1
⁄
2
") inlet and 3.81 cm
(1
1
⁄
2
") outlet and is designed for flows to 92.7 lpm (24.5 gpm).
This maximum flow rate was calculated at 300 strokes per
minute with 100 psig air inlet against 0 psig discharge head. The
A4 Plastic pump is manufactured with wetted parts of
polypropylene or PVDF. The center section of the A4 Plastic
pump is of aluminum or polypropylene construction. A variety of
diaphragms, valve balls, and O-rings are available to satisfy
temperature, chemical compatibility, abrasion and flex
concerns.
All wiring used to operate the pump should be placed and
connected according to the proper electrical codes. It is impor-
tant that the wiring is of adequate gauge to carry the current
required to operate the pump. In addition, it is necessary that
the electrical power supply is large enough to supply the
current required to operate the pump. Wiring should be above
ground level if possible (in case of fluid spill or leakage), and all
wiring and connections which could become wet or damp
should be made watertight.
If the pump is to be used in a self-priming application, be sure
that all connections are airtight and that the suction lift is within
the pump’s ability. Note: Materials of construction and elastomer
material have an effect on suction lift parameters. Please refer
to pump performance data.
Pumps in service with a positive suction head are most efficient
when inlet pressure is limited to .5–.7 Bar (7–10 psig). Prema-
ture diaphragm failure may occur if positive suction head is .8
Bar (11 psig) and higher.
The solenoid valve is rated for continuous duty; however, stop-
ping on an even number stroke count insures that the electrical
power is off when pump is stopped. This practice is safer and
also eliminates unwanted strokes when the system is shut down
and electrical power is off.
THE MODEL A4 WILL PASS 4.8 mm (
3
⁄
16
") SOLIDS. WHEN-
EVER THE POSSIBILITY EXISTS THAT LARGER SOLID
OBJECTS MAY BE SUCKED INTO THE PUMP, A STRAINER
SHOULD BE USED ON THE SUCTION LINE.
WARNING: Before installation, consult chart in Section
10B (page 30) to ensure proper electrical connection.
WARNING: The solenoid valve should not be used in an
area where explosion proof equipment is required unless
NEMA 7 valve is specified.
There are three coil options available in both NEMA 4 and
NEMA 7 ratings. One coil allows for 110V AC operation, one
allows for 24V DC operation, and the third allows for either 24V
AC or 12V DC operation. See Section 10B for options and part
numbers.