Centrifugal chemical pumps are ideal for

many applications, from filtration and circulation to storage and unloading.

Due to their harsh nature, corrosive chemicals must be handled carefully. As designers

establish their systems, they must select pumps that are constructed to withstand the

specific corrosive chemicals involved in their process.

Centrifugal Chemical Pump Types

Centrifugal pumps are available to transfer a wide range of flows. Using rotational

energy supplied by an impeller, these pumps are able to move liquids safely and efficiently.

Centrifugal chemical pumps are designed to transfer liquids that other pumps cannot safely

handle.

Centrifugal chemical pumps are manufactured in two main styles: mechanically sealed and

magnetically driven. These designs are distinct and are appropriate for different

applications.

Pumps With Mechanical Seals

A centrifugal pump features an internal rotating impeller with a portion that connects to

the motor through an opening in the pump housing. To prevent leakage, a mechanical seal is

used for this opening. These are typically made of ceramic, silicon carbide or carbon rings

that are carefully designed to seal the pump preventing leakage. One ring rotates as the

shaft turns, while the other remains stationary in the pump. As the fluid travels through the

pump, a small amount moves between these two seal faces to provide lubrication.

The main advantage to this type of pump is the initial purchase price. Compared to other

types of pumps, such as stamping pump,

sewage pump and

magnetic pump, the initial investment is

typically lower. A secondary advantage is the potential to handle some solids.

Magnetic-Drive Centrifugal Pumps

As the name implies, magnetic-drive (mag-drive) pumps are driven by magnets. This

eliminates the direct connection between the impeller and the motor shaft, effectively

eliminating the need for a seal. Magnets are mounted on the motor shaft to transfer the motor

power through a solid barrier to other magnets inside the pump, which rotate the impeller.

The key advantage to this pump style is the lack of mechanical seal. With no seal to wear

out or leak, this pump style offers lower maintenance and greater longevity than mechanically

sealed pumps, and also, some models feature run-dry capability not commonly found among

mechanically

Centrifugal Chemical Pump Benefits

1. Corrosion Resistance

This benefit creates two advantages. First, the pumps allow manufacturers and processors

to transfer a wide variety of fluids, even those that would quickly cause corrosion in other

pumps.

Second, the pumps offer long service life. Even when used for extremely

corrosive chemicals, the pumps are able to withstand these conditions and deliver

enhanced return on investment (ROI) (Image 4).

2. Energy Efficiency

Centrifugal chemical pumps rank high in energy efficiency compared to other pumping

technologies. Their efficiency reduces costs both in the short term and over the life span of

each unit.

3. Smooth Flow

Some pumps produce pulsing flow. Non metallic centrifugal pumps avoid pulsing.

4. Proven Reliability

Centrifugal chemical pumps are a solid choice when reliability is critical. Evaluate

design and construction features to ensure the specified pump will be durable enough to

operate under the most extreme conditions in the planned application.

5. Low Maintenance

Despite long life spans, some pumps may require frequent routine maintenance that can

make them costly to operate. Fortunately, centrifugal chemical pumps have low routine

maintenance requirements.

6. Size Versatility   

Centrifugal chemical pumps are available in a wide range of sizes. The various models can

accommodate flow rates ranging from less than 1 gallon per minute (gpm) (1 liter per minute

[lpm]) to greater than 1,400 gpm (318 cubic meters per hour [m3/hr]).

7. Application Versatility

The same pump configuration is not suitable for every application. With centrifugal

chemical pumps, various configurations are available to provide solutions for multiple

applications. These versatile pumps are available in three configurations:

A. Flooded suction—These can be used when the liquid supply level is above the pump’s

centerline or impeller eye.

B. Self-priming—These can be used when the liquid supply level is below the pump’s

centerline or impeller eye.

C. Vertical—These pumps are typically submerged in the fluid, making them suitable for

applications where space is limited. Some manufacturers offer standard, nonsubmergible pumps

that can be mounted vertically outside the tank to save space.

Furthermore, the option of mechanical seal or magnetic drive sealless designs adds to the

versatility of these pumps. These two constructions cover a full range of applications. This

diversity also covers a range of budgets, making it easier to find a pump that is suitable

for each unique use.

Specifying a Centrifugal Chemical Pump

To spec the ideal pump for any application, the pump supplier needs key pieces of

information. To provide the required information, consider these questions about the fluid

and the application.

About the Fluid

What is the name of the fluid(s) the pump will transfer? This may include more than one

name if there will be a mixing of products or the fluid is a mixture of chemicals.

What is the concentration of the fluid? This helps determine the chemical’s level of

corrosivity.

What is the fluid temperature? Chemical resistance can vary by temperature, so this

quality is important to note.

What is the specific gravity of the fluid? This is used to select the correct motor power

and lift capacity.

What is the viscosity of the fluid at pumping temperature? This affects the flow, head

and motor power of the centrifugal pump.

Will the pump be used for solids? If so, the user must identify the hardness, particle

size and concentration of the solids. These details affect the material specs of the pump.

Is the fluid flammable or combustible? This affects what components and materials are

used for the construction of the pump.

About the Application

What is the total head? This is based on the piping system and is used for reviewing a

manufacturer’s pump head-capacity curves.

What is the flow rate? This is the volume of liquid that needs to be pumped per unit of

time.

What is the net positive suction head available (NPSHa)? This is the suction head made

available to the pump and provided by the piping system, which must be taken into

consideration to avoid damage to pump components.

What is the application? A detailed description of how the pump in

automatic control system will be

used allows the manufacturer to spec the appropriate pump.

What other materials are involved? Some materials may be suitable for some chemicals, but

they can be negatively affected by certain combinations of products.

What is the ambient temperature range? In settings where the temperature is not

controlled, this must be taken into account when selecting the motor and construction

materials.

What is the atmosphere environment? This helps determine the motor enclosure type.

What is the altitude? Atmospheric pressure affects maximum lift, NPSHa and motor cooling

ability.

Using the information about the fluid and application, partner with pump manufacturers

and knowledgeable, experienced pump distributors in order to specify the correct pump type

and the materials of construction to handle the chemicals involved.