GENERAL DESCRIPTION
The ARO diaphragm pump offers high volume delivery even at low air
pressure and a broad range of material compatibility options available.
Refer to the model and option chart. ARO pumps feature stall resistant
design, modular air motor / fluid sections.
Air operated double diaphragm pumps utilize a pressure differential in
the air chambers to alternately create suction and positive fluid pressure
in the fluid chambers, valve checks insure a positive flow of fluid.
This diaphragm pump was developed to address the unique problems
associated with pumping dry powders, which can pack out" inside the
pump fluid chambers, if not kept in a semiĆfluid state.
This system incorporates the use of special valves to introduce air or inĆ
ert gas* into the fluid chambers simultaneously to a pumping cycle in a
timed sequence which keeps the powder in a fluidized state during the
transfer process.
The main air distribution valve (252) is a double pilot actuated fourĆway
valve. It is a slave to the pump major air valve.
The distribution valve recognizes the signal from two pump major air
valve (259) ports (air dumps). These signals are converted into alternatĆ
ing output pressure distributions, which are injected into the fluid chamĆ
bers during the pumping cycle to fluidize the powder as the diaphragm
moves through the discharge stroke.
The flow of air supplied to the fluid chamber is controlled by the (248)
filter / regulator. Under normal operating conditions, this is the primary
control.
When air is supplied to the filter / regulator (248), the distribution valve
directs the flow of air into the fluid chamber that will dispense first for 3 to
8 seconds. The time delay then supplies the start signal to open the main
pump air supply valve. When the pump diaphragm reaches the end of
the discharge stroke, it reverses direction. The distribution valve then
shifts and shuts off the fluidizing air to the first fluid chamber as it applies
a burst of air to the second fluid chamber and fluidizes the powder in the
second chamber.
The air induction orifice (76) increases the air velocity prior to injection
point because of the orifice and it prevents clogging of the injector feed
line.
NOTE: The restart valve (258) is a bleed valve which will stop the pump
and then restart the pump by reĆinitiating the time delay cycle.
*NOTE: Use of other gases: Using only a gas to operate a 3" pump can
be rather expensive because of the high volume needed. Separate air /
gas inputs allow the fluidizing feature of this pump to utilize special inert
gas, such as Nitrogen or Argon (air), if necessary and still allow use of
standard compressed shop air for the pumping function.
The ability to introduce special gas also means special materials could
be injected through the fluidization lines. Applications may include such
materials as colorants, foaming agents, additives, neutralizers, etc.
AIR AND LUBE REQUIREMENTS
WARNING
S The air supply line or hose to the pump should be adequately sized
to carry a sufficient volume of air to the pump. The material inlet supĆ
ply tubing should not be too small or restrictive, which will inhibit maĆ
terial flow. The outlet material volume is governed not only by the air
supply, but also by the material volume available at the inlet.
S Air supply provided should be filtered to provide clean, dry air. A filter
capable of filtering out particles larger than 40 microns should be
used on the air supply. There is no lubrication required other than the
O" ring lubricant which is applied during assembly or repair.
S If lubricated air is present, make sure that it is compatible with the
Nitrile O" rings in the air motor section of the pump.
S NOTE: When using air for powder fluidization, make sure it is filtered
and very dry.
INSTALLATION
WARNING
S
S
S
S
S
OPERATING INSTRUCTIONS
1. Connect air supply to (263) main air supply control valve (30 Ć 40
p.s.i. / 2.1 Ć 2.8 bar).
2. Turn the air on.
3. Attach air (or gas) to (248) filter / regulator. CAUTION: Do not apply
excessive Fluidization Gas* Pressure (refer to note under General
Description").
4. At (248), turn on air (or inert gas) supply. There will be a 3 to 8 second
time delay, during which the pump will be fluidizing any powder left in
the pump from an earlier dispense. This time delay will occur on all
startĆups.
NOTE: Powder type materials can vary in flowĆability and the same setĆ
tings may not work universally. Factors such as density and humidity can
require changing the mixture of flow rate and fluidization air and some
experimenting should be expected.
Positive air (or gas) pressure must be supplied to the filter / regulator to
allow the pump to function. Powder will accumulate in the fluid caps if the
pump is not allowed to expel excess material before the pump shuts
down. Restart can compress some powders to a solid that may cause
the pump to fail. The pump should cycle until most of the powder has
been purged before it is shut down.
Calibration procedure on initial startĆup:
NOTE: Once these parameters are established for your specific applicaĆ
tion, they should not need to be changed.
1. Turn the flow and pressure on the (248) filter / regulator all the way
up.
2. Slowly decrease pressure and flow until pump begins to labor (work
harder).
3. Increase pressure and flow back to a point where the pump begins to
