What is the first thing that comes to mind when you experience pump shaft failure or damage? Most probably, need for a stronger pump shaft.
No doubt that stronger is better, but that doesn’t address the problem. A stronger pump shaft may help with fewer failures, but the problem of pump shaft failure mainly happens due to the shaft’s misalignment.
Running a pump with even the slightest shaft misalignment can cause vibrations resulting in bearing failure and pump shaft breakdown. Whereas properly aligned shafts reduce these vibrations, which improve reliability, prevent seal leakage, extend the bearing’s life, and avoid unnecessary failures.
So if you want to achieve efficiency gains and extend your pumps’ service life, then the first thing to look after is correct pump shaft alignment.
With these in mind, let’s look at what pump alignment is, its importance, and how you can detect shaft misalignment as well as prevent it.
By the end, you will have a firm understanding of how to achieve a successful pump alignment.
Pump shaft alignment is a process of aligning two or more shafts between a motor and a pump within a tolerated margin.
Power transmission from a motor to a pump is generated by the connection of the motor and pump shafts. This connection can be formed by using a straight shaft or through a flexible coupling.
Pump shaft misalignment is when two rotating shafts are not properly aligned with each other. There can be either an angular gap at the coupling area or the shafts could be imbalanced.
Shaft misalignment can cause major problems in pump systems. Some of the common problems caused by shaft misalignment include:
Well-lubricated and precisely aligned pump components are crucial for smooth and continuous pump operation.
A pump shaft is responsible for transferring energy from the driver to the pump shaft’s impeller. A basic pump shaft design handles the torque and rotational movement, which is crucial to a pump’s functions as it keeps stress within design limits.
In addition to this, proper pump shaft alignment also increases the shaft’s operation lifespan. A misaligned pump shaft doesn’t majorly affect motor effectiveness; however, a properly aligned shaft can make the transmission of power between the pump and motor more efficient and smoother.
Pump shaft alignment is very important as when the motor and pump shafts aren’t aligned, it produces excessive vibrations that can result in excessive noise generation from the pump.
Moreover, vertical and horizontal pump misalignment can damage seals and couplings, which can cause the pump to leak.
Pump shafts can either be misaligned or can become misaligned over time. Shaft misalignment can occur in two different positions, vertical or horizontal.
The two types of shaft misalignment are
In this type of misalignment, the shafts are not parallel to each other. It can be divided into vertical and horizontal pump shaft misalignments. Where in Angular horizontal pump shaft misalignment, the motor shaft operates at an angle to the pump shaft and operates in the horizontal plane.
On the other hand, in Angular vertical pump shaft misalignment, the motor shaft operates at an angle to the pump shaft and operates in the vertical plane.
In this type of misalignment, the shafts are parallel to each other in an offset way. It can be divided into vertical and horizontal pump shaft misalignments.
In Parallel horizontal pump shaft misalignment, the pump shaft is misaligned in the horizontal plane, and the motor shaft is moved away from the pump shaft horizontally. Both motor and pump shafts operate parallelly in the same horizontal plane.
Inversely, in Parallel vertical pump shaft misalignment, the shafts misalignments are in the vertical plane. This means that the pump shaft has moved vertically away from the motor shaft while operating parallelly in the vertical plane.
Even after aligning pump shafts properly during installation, they can get misaligned during pump operation. To make sure they are properly aligned, here are some of the commonly used pump alignment methods to use.
In this method, a straight edge is placed on the pump and coupling prior to inspecting the gap between the lower and upper coupling using a feeler gauge.
This method is mainly used in situations like when two shaft endings are close to one another or only one shaft is rotating while being aligned. This technique is more precise than straight edge alignment.
Proven to be effective, this method involves high investment in hardware systems. This method involved two dial indicators, one on the motor shaft and one on the pump shaft.
Sometimes these dial indicators are mounted on couplings too, though highly preferred to be mounted on shafts as there is a higher possibility of couplings being misaligned.
This is the most accurate method to align the pump shaft using a laser alignment system. This laser alignment system has a transmitter, and receiver with a laser diode and position sensor placed on the bracket and then positioned on one of the shafts.
The sensor emits a light beam towards a bracket on the other shaft. Then the reflective prisms return backs the beam to the first bracket.
Later a mini-computer accurately calculates the movements required to automatically align the two shafts.
The first way to determine the pump shaft misalignment is to check if there are any wear and bearing/ seal failures.
The second scientific way to detect pump shaft misalignment is through vibration analysis. Any excessive noise and vibrations in the pumping system indicate the misalignment of the pump shaft. The vibration analysis meter helps identify the vibration occurring in bearings.
Vibration analysis can be performed as preventive maintenance and monitoring to identify pump shaft misalignment and diagnose it.
Smooth and successful pump functioning requires proper pump maintenance. Carefully identifying and resolving pump shaft misalignment can save your pump from big damage.
We hope the above information will help you get a complete understanding of pump shaft alignment and why it is important for long pump service life.
Despite this, if you are looking for top-quality industrial pumps for your applications, you are at the right place.
Sujal Engineering is a leading industrial pump manufacturer in India, supplying a comprehensive range of industrial pumps that are highly capable of handling aggressive & corrosive fluids.
Contact us today to learn more about our product range.