What is a Horizontal Pump?

Pumps can be manufactured and installed in a variety of orientations depending on its design, the application and liquid being pumped. They can be installed Horizontally, Vertically, Submerged, or Immersed in the liquid with each design having an advantage over another.

But what are the differences between Horizontal, Vertical, Submerged, and Immersed pumps and why would you select one in preference over another? Below we discuss the difference between horizontal and vertical Pumps, what types are available in each configuration, and why a horizontal pump may need to be selected for a given process or application.

What is a Horizontal Pump? 

Horizontal pumps are a design where the pump head is located adjacent to the motor on a horizontal plane. Connected with or without a coupling, they can be baseplate mounted if long coupled, or with simply a footplate if close coupled.

They are one of the most widely used pump designs and are normally built to a DIN24255/EN733 Standard which covers the dimensions of the inlet & outlet flanges allowing interchangeability between brands, although overall dimensions and performance may slightly differ between what are classed as Standardised DIN24255/EN733 pumps.

There are many benefits to this design but let’s explore in more detail below.

Differences Between Horizontal and Vertical Pumps

Horizontal pumps share a few design similarities with that of vertical designs, with slight differences to allow the motor to be connected adjacent to or above the pump.

Below is an overview of each design with pictures illustrating the key differences in design:

Horizontal: This means that the motor is located on the same horizontal plane and adjacent to the pump. Designs can be close coupled meaning the motor is connected to the pump head without a coupling, or gearbox in between, or long coupled where the unit is coupled on a baseplate with a coupling and with or without a gearbox.

Vertical: This is where the motor is located above the pump with the pump and motor shaft orientated vertically, hence the descriptive name – vertical inline pumps. The motor can be close coupled to the motor meaning it is connected without a coupling, or long coupled via the use of a spacer bracket acting as a support for the motor, allowing the unit to be maintained without removal of the motor.

Immersed: Also referred to as vertical immersion pumps, an immersed design is where the pump head is immersed in the fluid, with the motor located outside of the fluid.

This is useful in applications such as the transfer of flammable liquids, where there are solids present in a pit requiring transfer, the temperature of the fluid is extremely hot preventing the use of other designs such as submersible, the viscosity of the fluid is high or where the NPSH Available (NPSHa) is very low.

This design lasts longer than a submerged model as the motor is not in contact with the fluid being pumped.

Submerged: In this design the pump is completely submersible, relying on the fluid to cool the motor. They can be mounted on guiderails to enable ease of removal, or with a freestanding footplate or feet to ensure the suction of the unit is lifted off the bottom of the tank, allowing fluid and solids to easily enter the inlet port. Working operation is controlled manually, via an integrated float switch or level controls.

Horizontal Pumps vs Vertical Pumps

Below we’ve broken down both the advantages and disadvantages of using a horizontal pump vs a vertical pump in your application.

3 Reasons when to use Horizontal Pumps vs Vertically Mounted Pumps

Here are 3 of the most common reasons why pumps must be mounted horizontally, and cannot be mounted vertically:

• Air Evacuation

In some designs, if units are mounted vertically, they are unable to function as designed. For example, if a self-priming pump is mounted vertically, it will be unable to evacuate air entering the casing, which is why an end suction centrifugal pump cannot be mounted vertically or used with a foot valve to become self-priming as in horizontal designs.

This is also the same for Side Channel Pumps which are self-priming when installed horizontally but are unable to self-prime and evacuate air when mounted vertically.

Other units which are of positive displacement design such as Vane, or Rotary piston could function vertically in theory, but there has never been a requirement for such design.

Vertical Self Priming Pumps are only possible when an air ejector or electric vacuum pump are used to evacuate the air.

• Forces on Inner Parts

Some models cannot be mounted vertically, as the internal components are unable to withstand the forces when mounted vertically.

This can be true in some designs of larger multistage pumps, where the bearings from the motor are used to withstand the radial forces within the pump.

These are unable to bear the thrust during operation when the unit is mounted vertically and unless the unit is redesigned to have a separate thrust bearing, it can never be mounted vertically.

• Weight of Motor or Other Parts
  

In some models such as multistage or large centrifugal pumps, the power to generate large flows or pressures can mean a substantial motor is required.

It is not uncommon to find such motors weigh in excess of a Ton. This weight then relies on a support frame above the pump to accommodate the load as well as the rotary forces of both the motor and pump.

As motors increase in weight, the feasibility of having motors mounted above pumps becomes less economical (unless of Vertical Immersion Design). Especially when a baseplate can be fabricated to accommodate the motor and pumps weight individually along a horizontal plane, reinforced by a concrete base which is much more economical to manufacture, install and maintain.

Similarly in some designs such as gear, larger designs of pumps may not be mounted vertically due to the weight of the gearbox, which will not only prove difficult to support vertically but also difficult to align and maintain during the unit’s lifespan.

What Pump Types can be Mounted Horizontally vs Vertically?

We've made a handy table below to highlight which pump types can be horizontally or vertically mounted.

Still have questions about horizontal pumps or vertical applications? If you are unsure of which pump to choose for your process, contact us via Phone, Email, Live chat, or our online form.

We are more than happy to explore the options available for your application and which design may be best suited for your process.