Pneumatic Diaphragm Pump

The QBY series pneumatic diaphragm pump is a new type of conveying machinery and a novel pump type currently available in the market.Powered by compressed air from an air compressor, this pneumatic diaphragm pump can completely pump and drain various liquids, including corrosive liquids, particle-containing liquids, high-viscosity liquids, volatile liquids, flammable liquids, and highly toxic liquids.It is available in eight conventional diameter specifications: 10mm (3/8"), 15mm (1/2"), 25mm (1"), 40mm (1 1/2"), 50mm (2"), 65mm (2 1/2"), 80mm (3"), and 100mm (4") — meeting diverse application needs of pneumatic diaphragm pump users.Three material options are provided for the pneumatic diaphragm pump: aluminum alloy, cast iron, and stainless steel.To meet the needs of different users, the diaphragms of the pneumatic diaphragm pump are made of nitrile rubber, neoprene rubber, fluororubber, or polytetrafluoroethylene (PTFE) depending on the type of liquid medium being handled.This pneumatic diaphragm pump is widely used in industries such as petroleum, chemical engineering, electronics, ceramics, textiles, paint, and pharmaceuticals. It is designed to pump various media that cannot be handled by conventional pumps.

Working Principle of Pneumatic Diaphragm Pump:

The working principle of a pneumatic diaphragm pump (a positive displacement reciprocating pump) is as follows: An air compressor delivers compressed air into the pump. The air distribution valve then drives the connecting shaft inside the pump's central body, which in turn drives the diaphragm inside the medium chamber of the pump body to perform horizontal stretching movements, thereby achieving the self-priming function for fluids.Inside the two symmetric working chambers of the pneumatic diaphragm pump, there is one flexible diaphragm in each chamber. A connecting rod integrates the two diaphragms into a single unit. After compressed air enters the air distribution valve through the pump's air inlet connector, it pushes the diaphragms in the two working chambers, driving the two diaphragms connected by the rod to move synchronously.At the same time, the gas in the other working chamber is discharged out of the pneumatic diaphragm pump from the back of the diaphragm.A pneumatic diaphragm pump consists of two main parts: an air flow structure and a liquid flow structure, which are completely isolated by the diaphragms on both sides.The pump can operate as long as the air source pressure is greater than 2 kg/cm².Under a working pressure of 5-8 kg, the high-pressure gas in the air valve chamber drives the connecting rod shaft to perform left-right reciprocating movements through the air flow guidance system. Meanwhile, the low-pressure gas after consumption is quickly discharged through the exhaust port of the pneumatic diaphragm pump.Under the alternating action of high-pressure and low-pressure gas on both sides, the connecting rod shaft drives the diaphragms on both sides to move left and right, causing alternating changes in air pressure in the volume chambers on both sides. This enables the continuous suction and discharge of liquid by the pneumatic diaphragm pump.The air distribution mechanism automatically introduces compressed air into the other working chamber, pushing the diaphragm to move in the opposite direction. This forms the synchronous reciprocating movement of the two diaphragms in the pneumatic diaphragm pump.Each working chamber of the pneumatic diaphragm pump is equipped with two one-way ball valves. The reciprocating movement of the diaphragm changes the volume inside the working chamber, forcing the two one-way ball valves to open and close alternately, thereby continuously sucking in and discharging the liquid.

Operation Precautions for Pneumatic Diaphragm Pump:

Start-up and shutdown load operation of the pneumatic diaphragm pump: The pneumatic diaphragm pump is driven by a variable-frequency motor. To avoid excessive or insufficient load during start-up and shutdown, it is strictly regulated that the load during start-up and shutdown should be controlled at around 30%. In addition, the instrument is set to ensure that load increase or decrease must be completed within a certain period of time — effectively maintaining the frequency converter from a process perspective.

Operation of the instrument air and lubricating oil pressure system for the pneumatic diaphragm pump.

      The instrument air pressure and lubricating oil pressure of the pneumatic diaphragm pump are interlocked with the main motor. The oil injection and oil discharge valves for the propellant fluid are air-closed valves, which require a constant air pressure to be maintained at all times. The minimum operating pressure for these two valves is not less than 0.4MPa, so the instrument air pressure is generally maintained above 0.5MPa. Even after the pneumatic diaphragm pump is shut down, the instrument air supply is not turned off to prevent insufficient or excessive fluid in the propellant fluid chamber. The air supplied to the valves is filtered and oil-atomized.During the operation of the pneumatic diaphragm pump, the lubricating oil pressure should not be lower than the pressure interlock value (0.15MPa), and the pressure difference across the lubricating oil outlet filter should not be too large. The steel ball inside the lubricating oil flow sight glass should be at the upper limit position. When adjusting the flow rate, the adjustment range should not be too large to avoid an excessive instantaneous flow rate that causes the pressure to drop too quickly, leading to an interlock shutdown of the pneumatic diaphragm pump.

Installation Diagram of Pneumatic Diaphragm Pump: