SANDPIPER Customized Industrial Diaphragm Pump Parts Air Valve Assembly

Our proprietary brand delivers complete technical solutions for fluid machinery and engineering systems. We specialize in industrial control and drive equipment, mechanical seals, and international field engineering support. Through our ecosystem of specialized technologies and product brands, we provide clients with high-level technical advisory, commercial support, and integrated product solutions — including pumps, variable frequency converters, servo drives, PLC-HMI interfaces, industrial control cabinets, motors, mechanical seals and assemblies, couplings, gearboxes, and turnkey engineering services (overseas on-site 3D scanning reverse molding for pump replacement parts and equipment debugging by our dispatched engineers abroad).

SANDPIPER Air Valve Assembly (also called the air distribution valve, pilot valve assembly, or spool valve unit) is the pneumatic control center of an air-operated double-diaphragm (AODD) pump. This assembly directs compressed air alternately between the two diaphragm chambers, creating the reciprocating pumping action that moves fluid through the pump.

The SANDPIPER air valve assembly consists of two main components: the main air spool valve (also called the air distribution spool) and the pilot valve. The main spool valve shifts position each time the pilot valve actuates, alternately pressurizing one diaphragm chamber while exhausting the other. The pilot valve is triggered by the diaphragm shaft at each end of its stroke, causing it to shift the main spool to the opposite position. This self-reciprocating sequence continues as long as compressed air is supplied.

Air valve assemblies are available in several configurations for SANDPIPER pump models: standard integral valve (internal pilot), remote-mount valve (external pilot), and spool-less valve designs. The valve body is typically manufactured from aluminum or stainless steel, with the spool and pilot components machined from hardened steel or engineering plastic, depending on the series and service.

Our SANDPIPER replacement air valve assemblies are manufactured as complete units (body + spool + pilot + seals) or as individual sub-components, precision-machined and leak-tested before dispatch.

1. Start Position — Compressed air enters the valve body inlet port and the main spool directs air to the left diaphragm chamber, pressurizing it and pushing the diaphragm shaft to the right
2. Right Diaphragm Exhaust — Simultaneously, the main spool connects the right diaphragm chamber to the exhaust port, allowing air from that chamber to vent to atmosphere
3. Stroke End & Pilot Actuation — When the diaphragm shaft reaches the end of its stroke, it contacts the pilot valve actuator, shifting the pilot valve position
4. Main Spool Shift — The pilot valve sends a pneumatic signal to the main spool, causing it to shift to the opposite position, redirecting compressed air to the right diaphragm chamber
5. Reciprocation Continues — The cycle repeats, creating continuous diaphragm reciprocation and pumping action

• Complete Assemblies & Sub-Components — We supply fully assembled and tested air valve units, or individual spools, pilot valves, seal kits, and body castings for rebuild
• Spool Surface Precision — The main spool is ground to tight dimensional tolerance and surface finish to minimize air leakage between ports and reduce air consumption
• Seal Material Options — Standard Buna-N, FKM (Viton), EPDM, and PTFE seals available for the valve spool and pilot to match chemical compatibility requirements
• Lubrication-Free Option — PTFE-impregnated spool designs eliminate the need for air line lubrication, reducing maintenance in oil-free compressed air systems
• Leak Tested — Every air valve assembly is pressure-tested for internal and external leakage before dispatch