The pump diaphragm is a key component of the diaphragm pump. It changes the volume of the pump cavity through the reciprocating movement of the diaphragm. That&#;s how diaphragm pumps can transmit fluid. When selecting a diaphragm in pump, users need to pay special attention to the choice of the diaphragm.

Read more

• Material of Diaphragm for mini pump
• The life of the diaphragm and its test conditions
• The shape and structure of the pump diaphragm
• Pump Diaphragm price and replacement

The following are the 4 key factors for choosing a diaphragm for pump.

Material of diaphragm for mini pump

According to different application requirements, the diaphragm in pump will be made of elastic materials. EPDM rubber (ethylene propylene diene monomer rubber) has become the most commonly used material for diaphragms, which because of its good processing properties, elasticity, price and life. However, EPDM rubber also has certain limitations, for instance corrosion resistance and high temperature resistance. Therefore, in order to meet some specific application requirements, different manufacturers have introduced different materials for miniature pumps. Such as FKM (Fluoroelastomers). FKM is also called Viton, FPM or fluorine rubber. Fluorine rubber diaphragm has better corrosion resistance than EPDM rubber. It can work at higher temperature, and has good cost economy, so it is also widely used. In recent years, PTFE-based corrosion-resistant materials have been widely welcomed in industry. It is also used in the field of enhancing the chemical compatibility of diaphragms. By covering the surface of the diaphragm with a layer of PTFE membrane, the corrosion resistance of the diaphragm can be greatly enhanced. However, as a plastic material, its elasticity and softness are worse than rubber materials. PTFE materials cannot be used on diaphragms that require high elasticity. When selecting the diaphragm material, the user should comprehensively consider the application fluid properties. Vacuum, gas pressure and flow-rate is important for a pump. The chemical composition of the medium will be another key factors. Chemical resistance are very important to select the most suitable diaphragm material.

The life of the diaphragm and its test conditions

The life of the diaphragm is the core factor that affects the life of the diaphragm miniature pumps. Pump diaphragms in the diaphragm pump will realize thousands of reciprocating movements per minute. It moves with the operation of the motor. Each movement will stretch and compress the diaphragm once. The rubber material used in the pump is subjected to such frequent movement. If it is not specially designed, fatigue will easily occur. Those fatigues will cause damage to the diaphragm and the pumps. Therefore, the manufacturer of the diaphragm pump will test the life of the diaphragm in the laboratory. The life of the diaphragm pump is generally related to its working pressure. During the life test, some manufacturers will carry out the test under low pressure load, some others may choose to test under the highest pressure. The life values of pump diaphragm&#;measured under different load conditions will vary greatly. Therefore, in addition to understanding the life of the diaphragm, the test conditions are also key indicators. At present, in the industry, some basic products can achieve a diaphragm life of more than millions reciprocating motions. Some manufacturers can achieve hundreds of millions of reciprocating motions under no load, while some manufacturers such as Hilintec have achieved billions of reciprocating motions under the maximum load.

The shape and structure of the pump diaphragm

The  diaphragm in mini pump is not only used to drive fluid movement, but also needs to divide the inside and outside of the pump cavity. It play a key role in fluid sealing. Only a diaphragm with good sealing performance can ensure that the diaphragm pump has good air tightness. Its structure and shape have a great influence on sealing performance. Currently in the industry, there are generally two categories, one of which is the connecting rod built-in integral diaphragm. It wraps the metal parts of connecting rod in the rubber. The rubber material itself is a whole. Its center does not have a connecting hole. The medium is in contact with the rubber of the diaphragm, so the medium cannot leak from the central connecting hole.This kind of diaphragm has good air tightness. However, it needs to wrap and embed metal parts during the vulcanization process of the rubber, which is a complicated process and high cost.

The second structure is a split diaphragm with a hole in the center. It uses a screw to connect the upper cover of the diaphragm to the connecting rod. This structure is simple and has the advantage of low cost, but the upper cover and the screw will come into contact with the medium. This structure brings the risk of contamination and corrosion. At the same time, the medium may leak out through the screw connection hole.

Pump diaphragm price and replacement

According to the above description, the price of the diaphragm has a strong correlation with the material used. The life of the diaphragm, and the structure of the diaphragm itself also affect product prices. Different manufacturers have different strategies on whether to provide diaphragm replacement kits. The different strategies adopted are mainly related to the repair service and life span. For example, some manufacturers can promise that the diaphragm pump motor can run continuously for 2 years, but the life of the diaphragm can work stably for one year under heavy load. In this case the user needs to replace the diaphragm in the middle of the pump life-time. When the diaphragm life is greater than or equal to the pump motor and other parts, the manufacturer generally chooses not to provide a diaphragm replacement kit.

The above are the four key factors for choosing a diaphragm for a pump. When selecting a diaphragm in diaphragm, the user will also conduct a comprehensive assessment of the medium temperature, surface treatment and cooperation with the pump. If you have other information that needs to be added, or any questions, you can also contact us. We are very happy to discuss with you about the technical issues of the diaphragm pump.

With competitive price and timely delivery, Huakai Anti-Corrosion Equipment sincerely hope to be your supplier and partner.

How to Choose a Diaphragm Pump &#; A Complete Guide

by Patrick Harmon

Diaphragm pumps are a great option for delivering high volumes of material at relatively low pressures. They typically resist wearing as they do not have a piston moving through a cyclinder but a simple rubber diaphragm or diaphragms that are displaced side to side allowing material to be sent (more on diaphragm vs piston pumps can be found here). So you may have finally decided a diaphragm pump is the right choice for your pumping needs, now it is time to learn how to properly select a diaphragm pump.

Factor 1 to Determine for Choosing a Diaphragm Pump &#; Pump Volume Requirements

Diaphragm pumps can pump material ranging from a gallon per minute up to hundreds of gallons per minute depending on the overall size of the diaphragm pump and the speed at which it is operating. An important fact when choosing a diaphragm pump is to ensure that you try to select a pump that will run at about 50% of its maximum potential capacity under normal use. Having the pump run at half of its maximum capacity will ensure the pump runs for a long time without need of much maintenance. Any diaphragm pump should list its operating capacity in Gallons per minute either in the service manual or on the sales sheet (see below for example).

Factor 2 in Choosing a Diaphragm Pump &#; Drive Type for Displacement Pump

There are a variety of options available to drive the diaphragm of a diaphragm pump back and forth enabling it to pump material. Common drive options for diaphragm pumps include electric drive or air driven pumps. The drive will be important because it can impact where the pump will operate and the if the diaphragm pump can be safely used. Electric drive diaphragm pumps will be able to run anywhere electric is available but are typically not a safe solution for areas where hazardous levels of flammable materials are present (like in paint areas).  In contrast air operated diaphragm pumps will work anywhere where compressed air can be provided to drive a diaphragm and are safe even around paints and similar materials because air doesn&#;t provide a source of ignition.

Factor 3 when Choosing a Diaphragm Pump- Materials the pump is composed of

Diaphragm pumps are offered in a variety of material builds. In general, the most common options that are available for diaphragm pump materials include the material that the ball and seat of the pump are made of, and the material that the pump body is made of. There is a lot to be considered but in general common options for coatings includes stainless steel ball and seats and PTFE diaphragm materials. Stainless steel will be more wear resistant but expensive while PTFE is more cost effective but may not hold up to abrasive materials as well.  Additionally stainless will tend to be more resilient to heat.

Factor 4 when Choosing a Diaphragm Pump &#; The Pumps Performance Curve for Air Operated Diaphragm Pumps

Any diaphragm pump will have a performance curve which will give you a lot of additional detail on the pump. Common information that a diaphragm pump performance curve will address will include how much volume (CFM) of air the pump will require at various operating levels and how much as well as how far the material can be supplied at various operating levels of the pump. Below we have taken a sample pump curve and broken down the components that are shown. The important thing to know for your particular diaphragm pump is that you have the proper amount of air for your pump to operate and that the pump will be able to deliver material at the rate you want and over the distance you need to deliver material. As an example, the chart below shows a pump performance curve. On the right side of the chart is the distance you want to move material, on the left side is the pressure the pump will need to be run at, along the bottom is the gallons per minute of material you will want to deliver. You will select a distance you need to deliver material over (in our example 40 feet), then you will select how many GPM you need to deliver (20 in the example). Next, move up from GPM to find the solid line that corresponds with pumping material the distance you want it to be moved. This line will be curved and you will follow the curve to the left to find the pressure required to deliver material a given distance at a given GPM.  In our example to move 20 GPM of material with this pump over 40 feet will require 60 PSI. Finally, you will locate the nearest curved dotted line on the diaphragm pump curve to find the CFM required for this level of performance which would be 20 CFM. The important thing to check is that the diaphragm pump your considering will be able to supply the amount of material you want (remember you will typically want the pump to be running at about 50% capacity at most to reduce wear though the curve will show higher operating rates as options), over the distance you want, and you have the air you need to run the pump.

Ultimatley a diaphragm pump is a great way to deliver large volumes of material quickly and effectively. To ensure you get great results from your diaphragm pump, consider the four factors we discussed here to look at when choosing a diaphragm pump. By following this simple advice you will be able to ensure you select a diaphragm pump that will last and perform well. If you need further advice on diaphragm pumps contact us today.