Fire Pump Shaft Alignment

While the installation of a life safety system to your property is a crucial line of defense against fire damage, you should remember this step is only half the battle. Regular maintenance and proper care for the system are essential to ensuring everything works exactly as it’s intended to if disaster strikes. A significant part of keeping all of your equipment running correctly includes ensuring proper alignment between your fire pump’s shaft and the shaft of the pump motor which is inspected through our fire pump shaft alignment process.


Fire pump misalignment arises when machinery couplings within the device have shifted from their co-linear position, meaning they are no longer positioned across from one another in a straight, functioning line. Shaft misalignment can prove very costly. In fact, roughly fifty percent of all costs related to breakdowns in rotating machinery like fire pumps can be attributed to a misaligned shaft. That’s why regularly guaranteeing a pump’s proper alignment should become an important investment.

There are two kinds of misalignment: parallel (also known as offset) and angular. In short, a parallel misalignment includes two shafts that remain aligned across from one another in a parallel fashion, but whose center lines have been offset vertically and no longer line up. An angular misalignment includes two shafts that have, over time, become titled and run at an angle to one another. In either of these cases, you’ll want to have a professional perform a shaft alignment and relieve your pump of these conditions.


In order to perform an accurate alignment, a professional will first undergo the stages of pre-alignment. This process includes inspecting the pump couplings to verify there is sufficient lubrication and/or one needs immediate replacement, as well as checking for loose bolting or any overt visual pipe strain. A disintegrating pump base also represents a serious issue to be caught and dealt with during pre-alignment. Perhaps most infamous in the pre-alignment stage, however, is the challenging phenomenon known as SOFT FOOT.


Soft foot is known for its damaging effect on both the alignment process and even more seriously, the reliability of the fire pump itself. Causes of this fire pump “disease” are varied, but in the most basic terms: soft foot is the erroneous contact between a machine casing and the baseplate of the system that supports it. This kind of improper, uneven distribution of the system’s “footing” can cause the fire pump to experience a non-uniform amount of contact with its surface and for lack of a better image, “wobble”, almost like an uneven wooden chair (which can throw off the pump severely). Much like the kinds of misalignment among couplings, the two kinds of soft foot are also known as parallel and angular, where, respectively, the faulty foot is either running parallel to the ground or encounters a surface at an angle. If a system is suffering from soft foot, then it is likely it’s experiencing a combination of these two kinds.


One important, and easily solvable, factor that leads to soft foot is simply the debris, dirt, and grime that becomes wedged in between footpads, shims, and the feet of the system. It doesn’t take much for substances like this to disappear up under the system’s feet and create problems that can lead to the symptoms of this soft foot condition. One benefit of regular maintenance of fire pumps is that inspectors will be able to consistently clean your system and ensure it never gets too dirty to create larger issues.

Soft foot can also potentially rear its head if any of the following conditions are met:

  • Warped machinery baseplates, foundations, or feet
  • Dents or abrasions in the machine base or feet
  • Insufficient amount of shims beneath the system’s feet
  • Excessive tension on the system’s feet from jack bolts


A trained professional will know that the first step in solving soft foot will be to confirm that it’s even there! This will involve ensuring that the fire pump system’s base plates and foundations are leveled correctly to specifications. Additionally, by loosening the machine’s bolts and applying force with a pry bar under each foot, an inspector can accurately check for soft foot’s presence. Correcting soft foot then involves applying a shim, a kind of wedge, to reinforce the proper positioning of the system. In simpler terms, this is almost like sticking something underneath a leaning chair to make it balanced and sit up right.

Eradicating soft foot is essential to ensuring the effectiveness of your fire pump system and its financially-beneficial reusability.


After a professional completes the pre-alignment process, including cleaning the fire pump system’s feet and doing his part to minimize any signs or effects of soft foot, he or she will move on to the realignment of the fire pump and motor’s shafts themselves, the most important part of this process.

While in years past, more traditional methods were developed and utilized to ascertain proper alignment such as visual estimation with a straightedge or the time-consuming process of employing dial indicators, technicians today use a laser-guided tool approach. Generally speaking, this process is quicker, simpler, and more accurate than any other used before. Two units, one to cast a laser and one to detect it, are mounted to the fire pump shaft and the pump motor shaft (one on each) and activated by a handheld control instrument by the inspector. As he or she manually moves the misaligned shafts of the pump and the motor into place, the laser will provide real-time information regarding how close the system is to returning to proper shaft alignment and will signal when this threshold has been met, with full accuracy. This process is the latest in the ever-evolving industry as we move away from less accurate, more traditional shaft alignment methods.

As you can surely guess by now, fire pump alignment is a very consequential and important task, and as such should be done as quickly as possible from the moment the pump’s and motor’s shafts fall out of line. To safeguard against waiting too long from the moment this happens, it’s recommended to invest in regular inspection and maintenance of your fire pump system. Otherwise, you may put yourself at risk of spending more money, wasting more energy, and experiencing more wear and tear on your system than was ever necessary.

Contact a professional at Crisp LaDew for a fire pump inspection today.