Owner manual
avbmdl1sm-rev0111 Model AVB Metallic Page 8
• The system head exceeds the air supply pressure to the pump.
• Increase the air inlet pressure to the pump. Most diaphragm pumps are
designed for 1:1 pressure at zero ow.
• Check ESADS+, including pilot valve assembly and main air valve assembly.
• Disassemble and inspect the main air distribution valve, pilot valve, and
pilot valve actuator pins. Check for scores, wear, or damaged o-rings. Replace parts as necessary.
Refer to the exploded view drawing and air valve section (P.18 & 20).
• Blocked discharge line.
• Check for obstruction or closed discharge line.
• Blocked pumping chamber.
• Disassemble and inspect wetted chambers of the pump. Remove or ush
any obstructions. Refer to page 14 for disassembly.
• Restricted or undersized air line.
• Make sure there are no obstructions or restrictions in the air inlet to the
pump. Install proper size air line and/or air line equipment. Refer to air supply section (p.7) air inlet
plumbing recommendations.
• Restricted or undersized suction piping.
• Make sure there are no obstructions or restrictions in the suction line or
related suction components such as screens or strainers. Install the proper size suction line and/
or equipment. It is recommended that any suction line components and pipe size be at least the
same size as the suction line thread size to the pump. Though best results will always be realized
if the line size of the suction line is increased by one size. Refer to the installation section (p.5) for
recommended suction plumbing recommendations.
• Blocked air exhaust mufer.
• Remove mufer, clean or de-ice and reinstall.
• Excessive Suction Lift.
• For lifts exceeding 20 feet (6 meters), lling the pump chambers with liquid
will prime the pump in most cases. If not, place pump closer to uid level.
Suction line cavitation.
• If no obstructions are in the suction line of the pump, decrease the inlet
air pressure and/or volume to the pump. This will slow down the diaphragm speed and reduce the
cavitation.
• Partially blocked exhaust mufer.
• Remove mufer and make sure that some of the material being pumped has
not migrated into the mufer element. If it has, replace the element or clean it and reinstall. If product
has made it to the mufer, then the diaphragm assembly will need to be inspected. Refer to the
Diaphragm Replacement section (p.15).
• Suction side air leakage or air in the product.
• Visually inspect all suction side gaskets, seals, as well as pipe and pipe
connections.
• Excessive ooded suction in system.
• Check height of uid above pump. For ooded conditions, exceeding 10 feet
(3 meters) of liquid, install a back pressure device in the exhaust side of the pump.
• Worn or misaligned check valve or check valve seat.
• Disassemble the wet end of the pump and inspect check valves and seats
for wear and proper seating. Replace them if necessary. Refer to the Check Valve section (p.15) for
disassembly instructions.
• Obstructed check valves.
• Disassemble the wet end of the pump and look for obstructions that may
prevent the check valve from seating on the seat. Look for damage on the valve and the seat. Replace
them as necessary. Refer to the Check Valve section for disassembly (p.15).
• Rigid pipe connections.
• Install exible pipe isolators or expansion joints between the plumbing and
the pump.
• Pulsation in the discharge line.
• Excessive pulsation in the discharge line may be corrected by installing a
Tranquilizer Surge Suppressor.