Making the right choice – how to identify the best small scale specialized pump for your industrial application

Finding the right pump for your application can be a daunting task. With so many different models available, in different configurations, how do you find the one that best fits your needs?

From general use to more specialized applications, identifying the right pump can not only save you time and money, but can also optimize operations to increase the life of the system as a whole. In more specialized applications, like those involving food or chemicals, there is little room for error when it comes to having the right equipment. This puts a huge premium on making the right choice.

Outlined below are some of the most common industrial pumps, as well as factors to consider when choosing the ideal pump for your job. While the below serves as a practical guide, you should always consult a trained technician to ensure the pump meets the application’s needs. Also be sure to check out our post Making the right choice – the top 8 things to consider when specifying a controlled flow pump as there are several things to consider before determining which type of pump is right for your application.

Flexible Impeller Pumps

What is a flexible impeller pump?

Flexible impeller pumps (aka FIP) combine the priming features of positive displacement type pumps with the general transfer ability of a centrifugal pump. These types of pumps can transfer thin or viscous liquids and depending on the configuration, can handle solids in suspension without damage or heat transfer. FIPs can be mounted at any angle, pump in either direction with equal efficiency, and continue to operate even when air passes through the system.

FIPs are “flexible” in nature; you can configure the pumps with either a high- or low-pressure impeller and vary the RPMs to suit the installation. Flexible impeller pump bodies can be made from bronze, stainless steel or even plastic and there are several rubber compounds available for the impeller depending on their intended use.

When can you use a flexible impeller pump?

Flexible impeller pumps are used in pharmaceutical applications for ingredient transfer, dairy tanker transfer, or heavy-duty applications such as diesel transfer in construction or ballast pumping in marine.

How do flexible impeller pumps work?

1. As the shaft spins the impeller, the vanes of the impeller are forced to bend and flatten on one side of the pump’s housing (either moulded or with a cam insert) as they rotate, creating varying-sized cavities.
2. This bending squeezes the chambers between the vanes. As a vane goes around a curved section of the housing, the increasing space between the vane and the housing creates a low-pressure zone. This low pressure draws fluid in through the inlet of the pump. As the flexible impeller blades contact the offset cam, they bend with a squeezing action that provides a continuous and uniform flow.
3. On the opposite side of the housing, the vane compresses against the smaller chamber due to its natural shape and the rotation. This squeezing action pushes the trapped fluid out of the pump through the discharge outlet.

Sliding Vane Pumps

What is a sliding vane pump?

The unique design of sliding vane pumps includes a rotor, vanes, and a housing which offers self-priming, sustained performance and trouble-free operation. Some models can even run dry for short periods, in some cases. They are also easy to maintain as the vanes can be easily replaced without having to remove the pump from the piping system.

When can you use a sliding vane pump?

Sliding vane pumps are ideal pumps for transferring diesel fuel, light oil, and fluids in diesel refueling applications, construction equipment (including asphalt paving machines and concrete cutting machines) and oil draining applications.

How does a sliding vane pump work?

1. As the shaft rotates the rotor, centrifugal force pushes the vanes outward. Spring mechanisms or sliding surfaces can also aid in pushing the vanes against the housing wall.
2. The extended vanes form sealing “walls” along the cam-shaped housing, creating a vacuum in the crescent-shaped chambers between the vanes. Fluid flows into the pump chamber through the inlet port as these chambers expand.
3. The continued rotation of the rotor carries these sealed chambers filled with fluid around the housing.
4. On the outlet side of the housing, the cam shape forces the vanes back into their slots. This decreases the volume of the chambers, pushing the trapped fluid out of the pump through the discharge port.

Oscillating Pumps

What is an oscillating pump?

Oscillating pumps, sometimes called solenoid pumps, use an AC electrical coil rather than a motor to power the pumping action. These pumps provide a compact solution for low-flow, high-pressure applications. Oscillating pumps are great for providing a smooth flow, most are self-priming, and some can handle small, suspended particles. They have a relatively simple design with few moving parts leading to reliable operation.

When can you use an oscillating pump?

Oscillating pumps are ideal for floor care machines, steam irons, steam generators, steam cleaning systems, medical appliances, air conditioners, and cooling systems.

How do oscillating pumps work?

1. When electricity flows through the solenoid coil, it creates a magnetic field that pulls a metal armature or plunger attached to the diaphragm.
2. This pull on the armature stretches the diaphragm inwards, decreasing the volume of the pump chamber on the fluid side. This creates a low-pressure zone.
3. The low pressure in the chamber draws fluid through the inlet check valve, filling the chamber.
4. As the current is switched off or the magnetic field weakens, the spring pushes the armature and diaphragm back to their original positions.
5. This pushing motion on the diaphragm increases the volume of the fluid chamber, creating pressure. The pressure forces the fluid out through the outlet check valve.

Diaphragm Pumps

What is a diaphragm pump?

Diaphragm pumps are driven in several different ways, either hand, air operated (AOD), or motor driven (MDD). Motor driven diaphragm pumps will have an AC or DC motor attached to a pump head with anywhere from one to several chambers in the pump head to smooth and increase flow. The more chambers in a pump head, the smoother the flow and the larger the chamber, the more the flow increases.

Diaphragm pumps are typically self-priming, able to be run dry for extended periods with no damage and are typically quieter than flexible impeller pumps.

When can you use a diaphragm pump?

These types of pumps can be found in applications such as spraying, misting, carpet cleaning, water systems, chemical transfer, and car wash.

How do air or motor driven diaphragm pumps work?

1. The motor starts and begins rotating an offset bearing attached to the shaft.
2. 1.     The offset bearing connects to a diaphragm plate that converts the left/right motion 90º to in/out motion.
3. As the diaphragm plate moves in and out, it transfers the motion to pistons attached to the diaphragm.
4. When the diaphragm pushes outwards towards the motor, a low-pressure zone is created in the pump head and draws the fluid into the pump head through one set of inlet check valves. 
5. On the return stroke (diaphragm moving towards the pump head), the diaphragm creates a high-pressure zone and forces the fluid through another set of check valves, out of the pump head.

Centrifugal Pumps

What is a centrifugal pump?

Centrifugal pumps are a workhorse in the fluid handling world. They use a spinning impeller to transfer energy and boost the pressure of a liquid. They have a relatively simple design with few moving parts, making them reliable and cost-effective. Centrifugal pumps can achieve high flow rates and can handle a wide range of liquids, from clean water to viscous fluids with some solids, making them suitable for many small and large-scale applications. The flow rate can be regulated from maximum output to no flow with no damage to the pump. While they can achieve good flow rates, they typically have lower pressure capabilities compared to some positive displacement pumps. Some centrifugal pumps require priming, meaning they need to be filled with liquid before they can start pumping efficiently.

When can you use a centrifugal pump?

Depending on the model and the component materials, centrifugal pumps are an excellent pump for transferring, spraying, circulating, and recirculating fluids in applications including hot and cold beverage vending and automotive maintenance.

How do centrifugal pumps work?

1. A motor causes the impeller to spin rapidly inside a housing.
2. As the impeller blades rotate, they fling the fluid outwards due to centrifugal force (the same force that makes clothes stick to the outside of a spinning washing machine).
3. This outward movement of the fluid creates a low-pressure zone near the center of the impeller, thus creating a vacuum to draw more fluid into the impeller housing. The low pressure at the center continuously draws fresh liquid in through the inlet port.
4. The high-pressure fluid on the outer edges of the impeller housing pushes the fluid to the discharge, out of the impeller housing.

The Ideal Pump for Your Application

With so many options available, we recommend that you consult your solutions provider if you are unsure about which model best suits your application or use.