What Is Pump Alignment?
Pump alignment is an essential part of production. Only when a pump is correctly aligned can power efficiently and safely flow from your machine’s motor shaft to its pump shaft through a coupling. The pump and motor should rotate on the same axis, appear balanced, and operate without loud vibrations or noises. When a pump shaft is correctly aligned and sealed, it can prevent costly repairs and lengthen the life of your equipment.
How to Align a Pump and Motor
To properly align your pump and motor, they must be lined up both horizontally and vertically.
To make for easy vertical adjustments, fix your pump to a secure base, lift your motor, and place shims — thin, slotted materials used to adjust positioning between two parts. For horizontal adjustments, have jack bolts secured, and a pry bar or a hammer ready to knock parts into position.
Visual indicators, like a good view of the coupling, can already hint at how much adjusting will need to happen. It’s also worth testing how positioning changes when the bolts are tightened, because if the shaft shifts then you know it has a soft foot condition and is not stable enough to be correctly aligned.
Once you’ve selected your tools, your team can utilize one of three common mechanisms to correctly align the pump:
1. Straight Edge Pump Alignment
This includes placing a straight edge and taper gauge between the two shafts. If an easy and speedy check is needed, this type of alignment is helpful, but remember it’s not as accurate as other methods.
2. Rim and Face or Reverse Dial Indicator Pump Alignment
Using two dial indicators, measure the misalignment and then calculate the angle between those two points. This process is far more accurate than the straight edge method. However, this method requires a great deal of time, skill and experience.
3. Laser Pump Alignment
This method includes using lasers to measure the position of two shafts. Laser shaft alignment tools can quickly and efficiently measure misalignment and help determine what adjustments need to be made. These tools are easy to use and highly accurate.
Throughout the installation and alignment process, it is important to document pre-alignment data and final pump alignment data. This information can help your maintenance team better strategize when and how often maintenance should be scheduled.
Determining Pump Alignment Tolerances
In addition to the position of your shafts, maintaining pump alignment requires deciding alignment tolerances — or how close the pump and motor at the coupling should be to one another. Tolerances depend on your pump’s rotating speed and the data collected on thermal growth — or how much the equipment expands due to heat generation during operating hours. They can cause performance to vary even when adjusted by thousandths of an inch.
The type of coupling you use will also change tolerance. For example, long spacer shaft couplings can handle more misalignment than short flex couplings.
When Should Pump Alignment Be Checked?
Unless you can hear unusual noise or vibrating coming from your pump, it’s possible that misalignment can go undetected without routine check-ups — that’s why pump alignment should be checked on a consistent basis.
A preliminary pump alignment test, even prior to installation, ensures that the foundation is secure. Concrete or grout are suggested to avoid unwanted stress on your equipment, and help prevent thermal growth and contraction.
Different Types of Misalignment
Any variance between the necessary position needed for power to flow between the motor and pump is a misalignment.
- Radial Misalignment: this is the offset between the centerlines of rotation.
- Angular Misalignment: is the angle between the centerlines of rotation.
There are four types of misalignment:
- Offset in the vertical plane
- Angular in the vertical plane
- Offset in the horizontal plane
- Angular in the horizontal plane
Axial Misalignment: some couplings require correct distance between the two halves so the placement on the shaft is important.
By returning to the mechanisms used for initial installation, you can realign your pump, decide how misaligned your equipment is, and investigate the cause in order to help prevent it from happening again.
Why is it Essential to Correct for Pump Misalignment?
Any misalignment that goes uncorrected can lead to malfunctions. That means the sooner you correct a misalignment, the more you can produce with the least cost possible.
More specifically, when your pump and motor are aligned, it reduces the chances of mounts, bearings, seals, couplings, and casings from premature wear — or even breaking. Maximizing the lifespan of the parts that make up your equipment means less failures, or quicker repairs when failures happen.
Another factor to consider during pump alignment and maintenance is energy use. If there is a misalignment, then that means useful energy is used overcoming strain vibration and heat instead of being used to power your machine.
