It is a positive displacement pump powered by compressed air that generates pressure through the deformation of a diaphragm. Featuring a simple structure and a wide range of material options, it can handle diverse liquids—including those that are corrosive, contain particulates, possess high viscosity, or are flammable and explosive—such as sewage, syrup, peanut butter, paint, and sludge. However, the variety of available materials can make model selection challenging. Here, the pump experts at Shanghai Shenyin Pump Manufacturing Co., Ltd. explain the key considerations for selecting a pneumatic diaphragm pump, focusing specifically on the following aspects:
1. **Liquid Temperature:** Determine the temperature of the liquid being pumped and whether it exceeds 80°C. Temperature significantly impacts pump performance; since diaphragms are typically made of rubber or PTFE (Teflon), excessive heat can cause the material to soften, preventing the pump from effectively drawing in or discharging liquid.
2. **Operating Conditions:** Select an appropriate model based on the required flow rate, as well as the concentration and specific gravity of the liquid. Rated flow and head figures usually represent maximum values; actual performance parameters should be verified against the pump's performance curve. Flow and head vary with air supply volume and pressure. As the maximum air supply pressure is 0.8 MPa, the maximum head is approximately 80 meters. Note that this 80-meter figure is based on water testing; if the pumped medium has a higher specific gravity than water, the achievable head will be lower.
3. **Material Selection (Pump Body, Diaphragm, and Seals):** Diaphragm failure accounts for a significant proportion of all pneumatic diaphragm pump malfunctions—sometimes exceeding 30% to 40% of cases. Therefore, the choice of diaphragm material is critical. When selecting a model, it is essential to specify the name of the medium being conveyed so that the diaphragm pump manufacturer can choose the appropriate diaphragm material. Given the vast array of chemical liquids—each with varying degrees of corrosiveness—precise characteristic parameters are required. Key factors include corrosivity, concentration, volatility, vaporization pressure, viscosity, and density. These properties are closely linked to material selection; one must consider the interaction between the medium and the materials used, paying attention to both metallic and plastic components. Only by taking these factors into account can you select the right pneumatic diaphragm pump for your needs.
How to Select a Multistage Pump
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