SANDPIPER HDB2 - Manual (Page 8)

hdb2smdl3sm-rev0614 Model HDB2 Page 6
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.
AIR EXHAUST
If a diaphragm fails, the pumped liquid or fumes can enter the air end of the pump,
and be exhausted into the atmosphere. When pumping hazardous or toxic materials,
pipe the exhaust to an appropriate area for safe disposition.
This pump can be submerged if materials of construction are compatible with the
liquid. The air exhaust must be piped above the liquid level. Piping used for the air
exhaust must not be smaller than 1" (2.54 cm). Reducing the pipe size will restrict
air flow and reduce pump performance .When the product source is at a higher level
than the pump (flooded suction), pipe the exhaust higher than the product source to
prevent siphoning spills.
Freezing or icing-up of the air exhaust can occur under certain temperature and
humidity conditions. Use of an air dryer unit should eliminate most icing problems.
BETWEEN USES
When used for materials that tend to settle out or transform to solid form, the pump
should be completely 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 valves and diaphragms at re-start. In freezing temperatures, the pump must be
drained between uses in all cases.
CHECK VALVE SERVICING
For best priming and most efficient pumping performance, it is important to maintain
check valves and valve seats in good condition for proper sealing. Need for inspection
or service of ball valves is usually indicated by poor priming, unstable cycling, reduced
performance, or pump cycles but will not pump.
Inspection and service of check valves requires the removal of five hex nuts and
one capscrew for each set of check valves (i.e., suction & discharge), providing
access to the two ball valves and their valve seats. New ball valves are 3 5 /
8
" (9.21 cm)
in diameter and will require replacement when worn to approximately 3 3 /
8
" (8.57 cm)
diameter.
DIAPHRAGM SERVICING
Need for inspection or service of diaphragm is usually indicated when unit pumps
from one chamber only and air is discharged out pump discharge port or when liquid
being pumped is discharged through air exhaust port.
To service diaphragms remove two capscrews which secure the chamber to the
manifold assembly, and twelve hex nuts that secure the chamber to the main pump
assembly. To remove diaphragms, loosen diaphragm assembly by turning it out of
the diaphragm rod using a 1 1 /
8
" (2.857 cm) socket or wrench. Removal of opposite
outer chamber will permit removal of second diaphragm assembly and diaphragm rod
as a unit.
To remove the diaphragm from the diaphragm assembly, hold the diaphragm rod
in a clamping device, making sure to protect the rod surface of shaft so as not to
scratch or damage it in any way. With a wrench turn the diaphragm assembly out of the
diaphragm rod. To disassemble the components, turn a 5/16-18 UNC capscrew by
hand into the tapped hole in the inner diaphragm plate. This will keep the plate from
turning while the capscrew is removed. To remove the capscrew, place the assembly
in a vise so the two protruding ends of screws are loose in the vise jaws (approximately
7/8" apart). Turn the center screw loose from the back plate and the assembly will
come apart.