Diaphragm Pump Selection

Are you in the market for a new diaphragm pump?
As you already know, this is a careful process that requires a lot of consideration.
In this video, we’d like to review some of the most important elements that need to be reviewed before designing your next diaphragm pump.

The first step in selecting a diaphragm pump is to correctly identify what you’re pumping. By clearly stating what you’re pumping, the pump supplier will be able to assist you with the correct material the pump needs. The goal is to provide a long service life. Incorrect material selection will result in expensive repairs, downtime ,and possibly even safety issues for the operator.

The pumping temperature of the fluid is also very important for the pump casing, seals, and diaphragms. An incorrect specification for the pumping temperature can result in the bad material choices. Premature pump failures with potentially dangerous consequences can be attributed to bad material that isn’t suited to the fluid temperatures.

The easiest way to think about viscosity is to consider how easily a fluid flows. Honey, for example, doesn’t flow really fast. But, if you heat it up, it’ll run like water. The viscosity of the honey is high when the temperature is cold and low when it’s warm or hot. It’s important to know the viscosity of the fluid being pumped. Before you start looking for a pump, you have to know the viscosity of the fluid being pumped.

FLOW RATE What volume of fluid do you need to be transfer? And how fast? For example, a 200-liter drum of fluid needing to be decanted into a process reactor may need to two minutes. That means you’ll need a pump with a flow rate of 100 liters per minute. On the other hand, if the 200-litre drum is in a bulk break operation where the operator is filling 500 ml bottles, a practical flow of ten seconds may be required. This translates into a flow of one litre per minute.

OPERATING PRESSURE When we consider how the pump will be installed or used, there are a few basic considerations. For example, where will the pump draw fluid from? Will the pump be standing on the base of a tank? If we have this type of configuration, where the pump is piped directly from the bottom of the tank, as soon as we open the tank valve, the fluid will flood the pump and it’ll be primed. This is what’s known as flooded suction. On the other hand, the pump may be located above the fluid level. In this instance, the pump is standing on a floor and the suction hose or pipe will go down below the pump into a sump or basement. The pump will be required to draw the water from below it, otherwise known as self-priming. In both instances, the suction head is derived from the highest or lowest fluid point above or below the pump.

You should always take the worst case scenario and design a pump to address that condition. In the end, selecting the right diaphragm pump is a careful process.