Inline Booster Pump

Inline Booster Pump

What is an inline booster pump?

An inline booster pump is a single-stage, single-suction centrifugal pump with its suction and discharge nozzles resting in a straight line of piping, or in line with each other inside a pump casing. Sometimes low-pressure water is undesirable even for simple tasks like teeth brushing or bathing because it is just a hassle to work with, an inline booster pumps helps to solve this problem. Low water pressure may be caused by gravity slowing down the fluid, higher elevation, long distance from the water source, additional water systems along with the piping network, or plumbing problems. The function of an inline booster pump is to increase the pressure and flow rate of water in a system. In essence, the pump provides the extra boost needed to raise the pressure and volume flow of water to the desired level. Inline booster pumps are specifically designed for constant pressure water supply and they operate on AC induction motors. In domestic and residential supply systems, inline booster pumps are used to provide the pressure needed to transfer water from the storage tank. Inline booster pumps can also be used to move liquids that have very close physical and chemical properties to that of pure water but at a temperature below 800C.

Inline booster pump

Inline booster pumps are the best choice for thin liquids, high flow rate, and high-pressure applications. These pumps are among the most common type of pumps in various market segments including the petrochemical industry, chemical plants, iron and steel metallurgy, light industry, sugar refinery, textile mills, HVAC, printing dyeing, pharmaceutics, paper mills, etc.

Components of an inline booster pump

The inline booster pump regardless of the type and pump manufacturer consists of the following components

  1. Motor- The function of the motor is to spin the pump impeller or simply to run the pump
  2. The impeller-the impeller moves fluid that comes in through the pump inlet and exits through the outlet
  3. Inlet and outlet- the pump inlet connects with the waterline while the outlet connects to the household water distribution piping
  4. Pressure or flow sensing sensor- These devices are used for measuring the pressure and flow rate of the fluid moving through the pump and to adjust accordingly.

Working principle of inline booster pump

An inline booster pump is connected directly to the main water line or pressure tank to supply enough water pressure to move water to the desired location or to provide adequate pressure for domestic purposes. During operation, the pump impeller is mechanically powered through the use of an electric motor or engine. The impeller is directly coupled to the electric motor via a shaft and it rotates at motor RPM. Water from the mainline strikes the vanes of the impeller where it is imparted with high kinetic energy and accelerated towards the pump casing, due to the centrifugal force acting on the impeller. In the pump casing, the speed of the water slowly decreases due to the gradually reducing size of the flow path. This leads to the conversion of the high kinetic energy into a high-pressure head before the water leaves the pump casing through the pump outlets, and enters the delivery pipe to be transferred to the desired location.

Characteristics of inline booster pump

An inline booster pump has myriad desirable characteristics such as the following:

  1. Directly coupled to an electric motor
  2. High efficiency
  3. Compact structure: small volume
  4. Easy to install and maintain; the pull-out design makes inline booster pump easier to access internal components
  5. The horizontal configuration is suitable for indoor applications because it has low headroom requirements

Types of inline booster pump

The inline booster pump has two main types depending on the orientation of the pump shaft: vertical inline booster pump and horizontal inline booster pump.

Vertical inline booster pump

This type of inline booster pump has a vertically oriented pump shaft. The shaft design is radial split and overhung. Vertical inline pumps are most suitable for high-temperature and high-pressure liquids as well as applications where the floor space is confined because they take up a small footprint. However, the over-hung shaft design becomes problematic and with high suction pressure, it is unable to balance the axial thrust und such operating conditions. Additionally, the vertical inline booster pump is inappropriate for the handling of liquid with high concentrations of dissolved gases because they may cause the failure of mechanical seals.

figure: vehicle inline booster pump

Horizontal inline booster pump

A horizontal inline booster pump has its shaft oriented horizontally between bearings or overhung. Most horizontal inline booster pumps feature an inline bearing shaft design, which makes them efficient even with high suction pressure. This type of booster pump is often very easy to maintain because the parts are easily accessible. It is also suitable for indoor applications, where vertical space is limited because it has low headroom requirements. The horizontal inline booster pump can be safely coupled with different prime movers such as electric motors, turbines, and fuels powered engines. However, a horizontal inline booster pump takes more floor space, and the working temperatures and pressure are relatively lower than for the vertical inline booster pump.

horizontal inline booster pump

Figure: horizontal inline booster pump

Applications of inline booster pump

Inline booster pump finds application in many kinds of water engineering including the following

  • Constant pressure water supply systems
  • Circular booster of cold and hot water in bathrooms
  • Iron and steel metallurgy
  • Air condition systems; district heating/cooling, drainage of central heating system
  • Heater circulatory system
  • Farmland irrigation and drainage
  • Support of firefighting equipment; firewater pumps
  • Industrial transfer of corrosive medium without suspended grain or medium.
  • Pumping non-flammable or non-explosive liquid without grain or fiber
  • Power plant water supply and drainage

Advantages of inline booster pump

  • Simple and compact design; hence requires relatively small installation space
  • Low initial installation and maintenance cost
  • High reliability and efficiency
  • Inline booster pumps are reasonably energy efficient. This is because they are not always in operation and kick into action when the user turns on the faucet to boost the pressure of the water supply.
  • The pump can handle a wide range of pressure and flow rates

Disadvantages of inline booster pump

  • An inline booster pump requires strong piping to handle high water pressure. In case of hidden cracks or damage in the pipe network, the high pressure exerted by the inline booster pumps may cause bursting and leakage.
  • Inline booster pump significantly adds to the cost of electricity
  • It requires a strict balance between the water flow rates. If the mainline flow rate is higher than the power of the inline booster pump, it can cause overspending or the pump may become ineffective.
  • Inline booster pump have mechanical seal problems due to the accumulation of gas in the seal chamber, which cause the failure of mechanical seals
  • Inline booster pumps may corrode as a result of the accumulation of seal leakage above the pump casing.

Selection of an inline booster pump

Deciding the right choice of inline booster pump comes down to the following several factors

The distance from the water source

For longer distances, you may need an inline booster pump with more horsepower or even two impellers.

The elevation of the water storage tank

If the water has to be delivered to a higher elevation tank through a one-inch diameter pipe that climbs several feet, then the inline booster pump should be capable to handle the weight of the water column.

Desired flow rate

You need to determine the gallons of water that you need every single minute for your application. The inline booster pump should be able to meet that flow rate for smooth operation.

Desired fluid pressure

High water pressure is desirable for some water used e.g., bathing. However, too much pressure can wear the plumbing system. For household uses, the maximum pressure of the inline booster pump should be below 60Psi. For other uses such as pumping fluid with dissolved solids, you may need to select a pump with higher pressure capabilities.

The location of the water source

Consider is the water source is situated below or above the pump. Is the water going to move uphill or up several-story buildings? If yes, you need a higher-pressure inline booster pump to be able to move a significant weight of water.

Troubleshooting inline booster pump

The inline booster pump does not start or run

  • A fault in the pump wiring e.g., loose connections or broken wiring (Inspect and fix loose connections, replace the broken wire)
  • The circuit breaker is open or the fuse is blown (reset the circuit breaker, replace the fuse)
  • Presence of an open circuit in the thermal overload (inspect the motor to establish the cause of overload, cool down, and restart the pump)
  • The motor is shorted out (Replace motor)
  • Inline booster pumps’ motor overheats and shuts off
  • The motor voltage does not match the line supply voltage (Check the motor supply voltage against the voltage specification on the nameplate)
  • Wrong wire size (Consult the national electrical codes for proper guide on the right wire sizes and circuit protection devices)
  • Impeller colliding with the pump casing or lacks a free rotation (Inspect and align impeller)

Inline booster pump vibrating too much

  • The inline booster pump impeller is partially clogged (Clean the impeller)
  • Poor coupling alignment (Inspect; align)
  • Oblique or unbalanced shaft (Check shaft and replace or balance as required)
  • Severely worn-out impeller (replace impeller)

Inline booster pump driver overloaded

  • Pump speed is too high (Reduce the pump’s rotational speed)
  • Coupling misalignment (Inspect; realign pump and motor as necessary)
  • Mechanical friction within the pump (Repair any obstruction or deflection)
  • Packing wound fixed too tightly (loosen nuts on packing glands as necessary)
  • Pump motor has shortcomings such as poor ventilation, or wrong positioning (Inspect the motor and do necessary repairs)
  • Fluid density or viscosity is too high (increase the motor size)

Inline Booster Pump bearings overheating

  • Poor coupling alignment (Check and realign)
  • Tightly fixed bearing covers (Loosen the bearing covers)
  • Excessive grease (Drain excess grease)
  • Insufficient lubrication or contaminated lubrication oil (Inspect the level of oil or grease, clean the bearing casing and lubricate)


An inline booster pump is a type of single-stage, single-suction centrifugal pump with its suction and discharge nozzle resting in a straight line of piping or in line with each other inside a pump casing. The function of an inline booster pump in water systems is to increase the pressure and flow rate so that it can be moved to the desired location, or for use in certain applications. These pumps are among the most common types of pumps in various market segments including the petrochemical industry, chemical plants, iron and steel metallurgy, light industry, sugar refinery, textile mills, HVAC, printing dyeing, pharmaceutics, pulp, and paper, etc. They are commonly used for providing constant water supply, air condition, heating and circulation of hot water, drainage, irrigation, pumping non-corrosive liquids among other uses.

Inline booster pumps offer several advantages such as ease of installation, simple and compact structure, high energy efficiency, and high reliability. inline booster pumps, However, also have some disadvantages including mechanical seal problems and non-stainless inline booster pumps can corrode. They also require stronger plumbing to prevent busting and damage of pipes under high water pressure, and also add to the electricity bill. Like any other type of pump, an inline booster pump is not immune to troubleshooting issues and this article also guides on the method of troubleshooting such challenges as bearing overheating, excessive vibrations, pump not starting, and more. An inline booster pump is an important piece of equipment that you should consider for your high-pressure flow applications.