Blagdon Pump X75 Metallic Flap Valve - Manual (Page 6)

x75mfvmdl2sm-rev0411 Page 4
PRINCIPLE OF PUMP OPERATION
This flap swing check valve pump is powered by compressed air and is a 1:1 pressure ratio design. It alternately pressurizes
the inner side of one diaphragm chamber, while simultaneously exhausting the other inner chamber. This causes the diaphragms,
which are connected by a common rod, to move endwise. Air pressure is applied over the entire surface of the diaphragm, while
liquid is discharged from the opposite side. The diaphragm operates under a balanced condition during the discharge stroke,
which allows the unit to be operated at discharge heads over 200 feet (61 meters) of water head.
Since the diaphragms are connected by a common rod, secured by plates to the center of the diaphragms, one diaphragm
performs the discharge stroke, while the other is pulled to perform the suction stroke in the opposite chamber.
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. This will maximize diaphragm life.
Alternate pressuring and exhausting of the diaphragm chamber is performed by means of an externally mounted, pilot operated,
four-way spool type air distribution valve. When the spool shifts to one end of the valve body, inlet air 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 porting of chambers is reversed. The air distribution valve spool is moved by an internal pilot valve which alternately
pressurizes one side of the air distribution valve spool, while exhausting the other side. The pilot valve is shifted at each end of
the diaphragm stroke by the diaphragm plate coming in contact with the end of the pilot valve spool. This pushes it into position
for shifting of the air distribution valve.
The chambers are manifolded together with a suction and discharge check valve for each chamber, maintaining flow in one
direction through the pump.
INSTALLATION & START-UP
Locate the pump as close to the product being pumped as possible, keeping suction line length and number of fittings to a
minimum. Do not reduce line size.
For installations of rigid piping, short flexible sections of hose should be installed between pump and piping. This reduces
vibration and strain to the piping system. A pulsation dampener is recommended to further reduce pulsation in flow.
This pump was tested at the factory prior to shipment and is ready for operation. It is completely self-priming from a dry start
for suction lifts of 20 feet (6.096 meters) or less. For suction lifts exceeding 20 feet of liquid, fill the chambers with liquid prior to
priming.
AIR SUPPLY
Air supply pressures cannot exceed 125 psi (8.61 bar). Connect the pump air inlet to an air supply of sufficient capacity and
pressure required for desired performance. When the air line is solid piping, use a short length of flexible hose (not less than 3/4"
(19mm) in diameter) between pump and piping to eliminate strain to pipes.
AIR INLET & PRIMING
For start-up, open an air valve approximately 1/2" to 3/4" turn. After the unit primes, an air valve can be opened to increase
flow as desired. If opening the valve increases cycling rate, but does not increase flow rate, cavitation has occurred, and the
valve should be closed slightly.
For the most efficient use of compressed air and the longest diaphragm life, throttle the air inlet to the lowest cycling rate that
does not reduce flow.
SERVICE AND OPERATING MANUAL
II 2GD T5
See page 17 for
ATEX ratings
X75 Metallic Flap Valve Pump
Design Level 2