Usage and selection of pneumatic diaphragm pumps

The pneumatic diaphragm pumps we use are all metering pumps, intended for dosing purposes, and not for use with sludge.

Pneumatic diaphragm pumps are a good choice as feed pumps for filter pressing; they are simple to operate, and the outlet pressure is determined by the pressure of the air supply, generally reaching 10 kg/cm2. Domestic pumps have a high repair rate; it’s better to choose those produced by joint ventures. Ingersoll Rand offers the greatest reliability, but at a higher price.

A diaphragm pump, also known as a pneumatic diaphragm pump or an air-operated double diaphragm pump. A type of reciprocating pump in which an elastic membrane, corrosion-resistant rubber, or elastic metal sheet divides the pump into two isolated sections: one for the fluid to be pumped and the other for the moving piston. In this way, the moving plunger does not come into contact with the liquid being transported. The back-and-forth movement of the piston is transmitted to the diaphragm through the medium on the same side, causing the diaphragm to move back and forth as well, thereby enabling the liquid to be drawn in and discharged through the spherical valve. The only component inside a diaphragm pump that comes into contact with the liquid being transported is the ball valve, which can be designed in a way that protects it from the effects of the liquid. In industrial production, diaphragm pumps are mainly used to transport corrosive liquids or liquids containing solid suspensions.

The main materials for pneumatic diaphragm pumps are four types: plastic, aluminum alloy, cast iron, and stainless steel. Electric diaphragm pumps are available in four materials: plastic, aluminum alloy, cast iron, and stainless steel. Diaphragm pumps use different types of diaphragms made from materials such as nitrile rubber, neoprene, fluororubber, polytetrafluoroethylene, and polyhexafluoroethylene, depending on the liquid medium in question, to meet the required specifications. Installed in various special occasions to pump various media. There are 4 combinations: positive-positive (air-closed type), positive-negative (air-open type), negative-positive (air-open type), and negative-negative (air-closed type). a) Process production safety ； b) Characteristics of the medium ； c) Ensure product quality and minimize economic losses. Flow characteristics: The flow characteristics of a diaphragm pump refer to the relationship between the relative flow rate of the medium passing through the valve and the displacement (the relative opening degree of the valve). The ideal flow characteristics include four types: linear, equal percentage (logarithmic), parabolic, and quick-opening. The commonly used ideal flow characteristics are only linear, equal percentage (logarithmic), and quick-open. Specifically, considerations should be made from the following aspects: ① Analyze and select based on the regulation quality of the regulating system ； ②Considering the process piping layout ； ③Analysis based on load variations. The selection method: the valve body type is the most important factor in choosing a diaphragm pump. There are many types of diaphragm pump valve bodies. (1) The shape and structure of the valve core are determined primarily based on factors such as the selected flow characteristics and unbalanced forces. (2) Wear resistance when the fluid medium is a suspension containing high concentrations of abrasive particles. (3) Corrosion resistance: Since the medium is corrosive, valve types with simple structures should be preferred as much as possible, provided that they can fulfill the regulation function. (4) Temperature and pressure of the medium: When the temperature and pressure of the medium are high and subject to significant fluctuations, a valve should be selected whose valve stem and seat materials are less affected by changes in temperature and pressure. 2. Selection of diaphragm pumps (1) Consideration of output force: Regardless of the type of actuator, its output force is the force used to overcome the load (mainly referring to the effects of unbalanced forces and unbalanced torques, in addition to forces such as friction, sealing force, and gravity). (2) Determination of the actuator type: Diaphragm pumps can be classified into three types based on the power source used by their actuators: pneumatic, electric, and hydrostatic. Specifically, there are pneumatic diaphragm pumps that use compressed air as a power source, electric diaphragm pumps that use electricity as a power source, and electro-hydraulic diaphragm pumps that use the pressure of a liquid medium (such as oil) as a power source. Category: Electronic-grade pneumatic diaphragm pumps – 3-inch plastic electronic-grade pneumatic diaphragm pump – A80. The VERDERAIR ALMATEC series now includes its largest-sized pump model, the A80. This pump features a high-capacity design and consists of three components: two diaphragm chambers and a central body. It is easy to operate and maintain. Both the inlet and outlet dimensions are DN80, with a maximum flow rate of 48 cubic meters per hour; the maximum allowable particle diameter is 15 mm. Diaphragm pumps, pneumatic diaphragm pumps, peristaltic pumps, hose pumps, and magnetic pumps – VERDERAIRALMATEC has a wide range of applications, from the chemical industry to the food industry. The smaller models of ALMATEC pumps are often used for circulation and sampling, while the larger models are primarily used in the chemical industry and the OEM market. The air valve is an essential component of pneumatic diaphragm pumps. The patented A80 air valve features a unique design that eliminates the use of any metals, offering high reliability and low noise levels. It provides a constant balanced load on the diaphragm, with no pressure difference, which in turn extends the lifespan of the diaphragm. Relevant parameters: Parameters of pneumatic diaphragm pumps. Model, Flow rate in m/h, Head in m, Outlet pressure in kgf/cm, Suction lift in m, Maximum allowable particle size in φ(mn), Maximum supply air pressure in Kgf/cm, Maximum air consumption in m/min. QBY-100: 0, 80, 50; 65, 170.3. QBY-150: 10, 50; 65, 170.3. QBY-250: 2, 40, 50; 67, 2.5, 70.6. QBY-320: 60, 50; 67, 4.0, 70.6. QBY-400: 80, 50; 67, 4.5, 70.6. QBY-500: 120, 50; 67, 8, 70.9. QBY-650: 160, 50; 67, 8, 70.9. QBY-800: 240, 50; 67, 10, 71.5. QBY-1000: 300, 50; 67, 10, 71.5

Features of pneumatic pumps: 1. Powered by compressed air. 2. It is a positive displacement pump in which volume changes are caused by the reciprocating deformation of a diaphragm; its working principle is similar to that of a piston pump. Due to the characteristics of its working principle, diaphragm pumps have the following features: (1) The pump does not overheat: Compressed air is used as the driving force, and the exhaust process involves expansion and heat absorption; therefore, the temperature of the pneumatic pump decreases during operation, and no harmful gases are emitted. (2) No electric sparks are generated: Pneumatic diaphragm pumps do not rely on electricity for operation, and grounding prevents the occurrence of static sparks. (3) They can handle liquids containing particles: Due to their positive displacement mechanism and ball valves at the inlet, they are less likely to get clogged. (4) The shear force on the material is extremely low: it draws in and discharges the material as it operates, resulting in minimal disturbance to the material; this makes it suitable for transporting unstable substances. (5) The flow rate can be adjusted by installing a throttle valve at the material outlet. (6) It has a self-priming function. (7) It can run without load without any danger. (8) Can perform work underwater. (9) It can transport a very wide range of fluids, from those with low viscosity to those with high viscosity, and from corrosive ones to viscous ones. (10) There is no complex control system, no cables, fuses, etc. (11) Small in size and light in weight, making it easy to move. (12) No lubrication is required, so maintenance is simple, and it does not contaminate the working environment due to leaks. (13) The pump can always maintain high efficiency; it does not decline due to wear and tear. (14) 100% energy utilization: when the outlet is closed, the pump stops automatically, preventing equipment movement, wear, overload, and overheating. (15) No moving seals are required, making maintenance simple and leakage prevention possible. There is no dead point during operation.

Common types: Pneumatic diaphragm pumps are a new type of conveying machinery that use compressed air as an energy source; the diaphragm inside the cylinder moves back and forth to perform work, thereby enabling the transport of various media. Media that can be transported: Pneumatic diaphragm pumps are suitable for transporting various corrosive, particulate-containing liquids, as well as liquids with high volatility, flammability, and **. Selection of materials: 1. The materials chosen for the housing include: aluminum alloy, cast iron, and stainless steel. 2. The materials used for diaphragms include nitrile rubber, neoprene, fluororubber, and polytetrafluoroethylene. Working principle of the pneumatic diaphragm pump: In the two symmetrical working chambers of the pump, there is an elastic diaphragm in each chamber. Connecting rods link the two diaphragms together. Compressed air enters the pump through the air inlet and then reaches the valve, pushing the diaphragms in the two working chambers to move, thereby causing the diaphragms connected by the connecting rods to move synchronously. Meanwhile, the gas in the other working chamber is expelled from the pump behind its diaphragm. Once it reaches the end of its stroke, the valve mechanism automatically introduces compressed air into the other working chamber, pushing the diaphragm in the opposite direction; this results in synchronized back-and-forth movement of the two diaphragms. Each working chamber is equipped with two check ball valves. The back-and-forth movement of the diaphragm causes a change in the volume within the working chamber, which forces the two check ball valves to open and close alternately, thereby continuously drawing in and discharging liquid. Uses: 1. Can suck up various types of sewage. 2. Can suck up various chemical corrosives, oil, mud, and cleaning residues. 3. It can suck up various **, flammable, and volatile liquids. 4. It can pump various strong acids, strong bases, and highly corrosive liquids. 5. It can suction various high-temperature liquids, with a maximum temperature tolerance of 150°C. 6. It can be used as a pressure supply device prior to various solid-liquid separation equipment. Features of pneumatic diaphragm pumps: 1. No priming water is required; the suction height is up to 7 m, the head is up to 50 m, and the outlet pressure is 6 kgf/cm². 2. It has good flow properties, allowing particles with a maximum diameter of up to 10 mm to pass through. When pumping mud and impurities, the wear on the pump is minimal. 3. The head and flow rate can be adjusted steplessly via the opening degree of the air valve (the air pressure is adjustable between 1 and 7 kgf/cm²). 4. This pump has no rotating parts and no shaft seal. By the reciprocating motion of a pair of diaphragms, various media can be pumped. Since the moving parts of the pump are completely separated from the medium being transported, there is no leakage of the medium, which prevents environmental pollution and potential harm to people. 5. It does not require a power source, allowing it to be used in flammable and explosive environments; it is safe and reliable. 6. It can be submerged in a medium to pump liquids instead of a submersible pump. 7. To start or stop the pump, it is sufficient to open and close the gas valve. Even if there is no medium pumping for an extended period due to unexpected circumstances or if the pump stops suddenly, it will not be damaged as a result. Once overloaded, the pump will shut down automatically, possessing self-protection capabilities. Once the load returns to normal, it will start operating automatically again. 8. Simple structure with few vulnerable parts. Diaphragm pumps have a simple structure, making them easy to install and maintain. When pumping the medium, the pump does not come into contact with moving parts such as valve gears and connecting rods, thereby preventing corrosion and wear of these components. 9. It can transport relatively viscous liquids. 10. No oil lubrication is required; even when running idle, it has no impact on the pump.

In short, the material should be aluminum alloy or stainless steel, with a rubber diaphragm. Stainless steel valve seat. Select the pump diameter based on the flow rate; generally, 1.5-inch or 2-inch pumps are chosen

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Our factory uses cast iron and 304 material.

PP diaphragm pumps are generally used with highly corrosive media