Chemical Pump Encyclopedia

Diaphragm pump structure: material selection and purchase guide

High quality diaphragm pump suppliers

Diaphragm pumps are indispensable and important equipment in modern industry and are widely used in chemical, pharmaceutical and electroplating applications. Their unique leak-free design and corrosion-resistant characteristics make them ideal for handling a wide range of fluids. However, there are many types of diaphragm pumps on the market, and how to choose the right diaphragm pump has become a challenge for many companies. As a professional diaphragm pump manufacturer, QEEHUA PUMP is committed to providing high-quality diaphragm pump products and offering professional selection guidance to customers. In this article, we will discuss the structure of diaphragm pumps and the function of each part, focusing on the material of the pump body and diaphragm plate and its selection, to help you better understand how to choose the right diaphragm pump according to specific needs.

Basic structure and function of diaphragm pumps

Pump body

The pump body is an important part of the diaphragm pump, directly contacting and holding the fluid. The choice of material for the pump body directly affects its durability and suitability. Common pump body materials include:

  • Cast Iron: Cast iron pump bodies offer good castability and cost effectiveness for general water treatment and low corrosive media. For example, a wastewater treatment plant using cast iron diaphragm pumps to deal with low-corrosive wastewater, not only reduces the cost of equipment, but also ensures the durability of the pump.
  • Stainless steel: Stainless steel pump bodies have excellent corrosion resistance and are suitable for a wide range of chemical media, including acids, alkalis and salt solutions. In the food processing industry, a large food factory chose QEEHUA PUMP’s stainless steel diaphragm pumps for conveying highly acidic food additives, ensuring a safe and hygienic production process.
  • Aluminum alloy: Aluminum alloy pump body is lightweight and has good corrosion resistance, suitable for manufacturing lightweight diaphragm pumps. A paint factory has adopted aluminum alloy diaphragm pumps, successfully reducing equipment maintenance costs and improving production stability.
  • Polypropylene (PP): Polypropylene is a plastic material with good chemical resistance, commonly used in the manufacture of economical diaphragm pumps, suitable for conveying non-corrosive or weakly corrosive media.
  • Polyvinylidene fluoride (PVDF): PVDF has very high chemical resistance and good resistance to high temperatures, and is suitable for conveying strong corrosive media. For example, in the semiconductor industry, a company uses PVDF diaphragm pumps to convey high-purity chemicals, ensuring product purity and production continuity.


Diaphragms are the core components of diaphragm pumps and are usually made of corrosion-resistant materials. Diaphragms made of different materials have significant differences in performance and applicability. Below are a few common diaphragm materials and their characteristics:

  • EPDM (EPDM rubber): EPDM diaphragms have good aging resistance and chemical resistance, and are suitable for conveying weak acids, alkalis, alcohols, ketones and other chemicals.EPDM also has excellent insulating properties, and is suitable for temperatures in the range of -40 to 130 ℃.
  • PTFE (polytetrafluoroethylene, also known as “Teflon”): PTFE diaphragm has excellent chemical resistance and high temperature resistance, suitable for handling strong acids, alkalis and other corrosive chemicals. Its applicable temperature range is -196 ~ 260 ℃, widely used in chemical and pharmaceutical industries.
  • FKM (Fluoroelastomer): FKM diaphragm has excellent aging resistance and chemical resistance, suitable for conveying most organic and inorganic solvents and petroleum-based oils. Its applicable temperature range is -20~200℃.
  • NBR (Nitrile Rubber): NBR diaphragm has good oil resistance and chemical resistance, suitable for conveying petroleum-based liquids and some chemicals, but the corrosion resistance is not as good as PTFE and FKM.

Diaphragm pump price influencing factors

Diaphragm pump prices vary greatly depending on the material, specification and brand. The following are some of the main factors that affect the price of diaphragm pumps:

  • Material cost: Highly corrosion-resistant materials such as PTFE and stainless steel are more expensive, while materials such as polypropylene and cast iron are relatively low cost.
  • Pump specifications: high-flow, high-pressure pumps are usually more expensive, because of their design and manufacturing costs are higher.
  • Brand: Diaphragm pumps of well-known brands are more expensive, but quality and after-sales service are also more guaranteed. Choosing manufacturers with good reputation and professional technical support, such as QEEHUA PUMP, can ensure the long-term stable operation of the pump.

Diaphragm Pump Supplier Selection

Choosing the right diaphragm pump supplier is crucial, and QEEHUA PUMP, as a leading diaphragm pump supplier, offers a wide range of high quality diaphragm pumps covering a wide range of applications. In addition, QEEHUA PUMP has a professional team of pre-sales and after-sales engineers to provide customers with a full range of technical support and services.

Diaphragm pump principle and its application

Chemical intake diaphragm pump is one of the types of diaphragm pumps specialized in pumping chemicals, using active compressed air to drive the reciprocating motion of the diaphragm to achieve fluid transfer. The following are its main structural components and functions:

  • Diaphragm Pump Connection Port and Fluid Pipe: connects the pump to the fluid pipe to ensure smooth fluid transfer.
  • Pump body or pump chamber: the main components to accommodate the fluid, made of materials compatible with the pump medium.
  • Pump diaphragms and pump ball valves, pump valves: control the suction and discharge of the fluid, determining the efficiency of the pump.
  • Air valve section: distributes compressed air to drive the reciprocating motion of the diaphragm.

Chemical suction diaphragm pumps offer a variety of advantages, including high corrosion resistance, ease of maintenance, and no need for mechanical seals. They have a wide range of applications and are suitable for pumping a variety of liquids or highly corrosive substances. For example, a large chemical company chooses QEEHUA PUMP’s diaphragm pumps with PTFE diaphragm and stainless steel pump body to transport highly corrosive chemicals, which not only solves the corrosion problem, but also greatly extends the service life of the equipment and improves the production efficiency.

Case Study: Diaphragm Pumps in Practice

Case 1: Diaphragm pump application in wastewater treatment

QEEHUA PUMP recommended a diaphragm pump with a cast iron body and EPDM diaphragm for a wastewater treatment plant that faced frequent damage and leakage of conventional pumps when treating wastewater with a certain degree of corrosivity. The pump is not only durable, but also effective in handling low-corrosive wastewater, reducing equipment costs and maintenance frequency.

Case 2: Diaphragm pump application for acid recovery

Acid recovery is the process of collecting, purifying and reusing waste acid generated during the production process. Acid recovery can reduce acid consumption, lower production costs and protect the environment. Diaphragm pumps are widely used in acid recovery due to their non-leakage and high corrosion resistance.

Diaphragm pump is an important equipment in acid recovery, which can effectively reduce acid consumption, reduce environmental pollution, and has good economic and social benefits.

Choosing the right diaphragm pump material

Choosing the right diaphragm pump material is critical, not only to the durability and service life of the pump, but also to productivity and safety. Depending on the type of fluid, temperature, pressure and other factors, choosing the right material for the pump body and diaphragm plate can significantly improve the performance of the diaphragm pump.

Fluid type

  • Corrosive media: PTFE, stainless steel, PVDF and other corrosion-resistant materials are suitable.
  • Weakly corrosive media: economic materials such as polypropylene and cast iron can be selected.


  • High temperature environment: PTFE and stainless steel are suitable for high temperature applications.
  • Low temperature environment: EPDM and NBR have good performance in low temperature.


  • High-pressure applications: Metal bodies and pressure-resistant diaphragms are suitable for high-pressure transfer.
  • Low pressure applications: Plastic bodies and general diaphragms are adequate.


The structural design of a diaphragm pump directly affects its performance and service life. By understanding the various components of diaphragm pumps and their functions, companies can choose the most suitable pump model according to their specific needs. The choice of materials for the pump body and diaphragm plate is a key factor to ensure the long-term stable operation of diaphragm pumps.QEEHUA PUMP provides reliable diaphragm pump solutions for customers with its rich product line, excellent technical performance and perfect after-sales service.

We hope that this article can provide you with valuable references in the diaphragm pump selection process and help you find the best fluid transfer solution. Choose QEEHUA PUMP for reliability and efficiency. No matter how complex your application needs are, we have the right diaphragm pump products and professional technical support to ensure your production process is smooth and worry-free.

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