Can Automatic Lubricators Work in Cold Temperatures?
This is a question that is often asked as the temperatures get colder and colder and the idea of lubricating those outdoor applications becomes very unattractive. In searching for a solution that will take care of those lube points without having to brave the cold to do it manually, automatic lubricators come to mind. But then you think to yourself, “Do they work in cold temperature applications”? The answer to that question is, “Yes they do work,” but only with careful planning and the proper system setup. Automatic lubricators won’t completely eliminate trips out in the cold (since you will still need to periodically check your equipment from time to time), but they will certainly limit the frequency (and duration) of the trips.
A Successful Setup
For cold temperature applications, having the correct setup is vital to achieving success. The first step in evaluating your setup is to quantify “cold temperature”, as this is relative and means very little out of context.The typical cold working temperature of most automatic lubricators is 0°F (17°C) with a variance of (+/- 5°).It is possible to lubricate at even lower temperatures, however this usually necessitates 
some Automatic Lubricators in cold weatheradjustments to the lubricant and/or the type of automatic lubricator used. If you are not already familiar with the different types of lubricators that are available, you may have to do a little homework prior to continuing.
The most commonly used lubricators found in industry today are either electrochemical (also referred to as “gas generators”) or electromechanical in nature.Although gas generator type lubricators can be used in cold weather they are generally not ideal due to their sensitivity to ambient temperatures.As the name suggests, the means of expelling lubricant from electrochemical lubricators is through a chemical reaction which generates a gas.As the gas expands inside this closed space, lubricant is forced out.The more volatile the reaction, the faster the gas expansion, and thus the faster the flow rate of the lubricant.This process is subject to the laws of physics which (in very simple terms) dictates that the colder the ambient temperature, the slower the reaction.Conversely, the warmer the temperature the faster the reaction takes place.The bottom line is unless you’re in a geographic area that tends to have constant temperatures year-round; the rate of lubricant flow to your lube point will be somewhat unpredictable (at best) using this type lubricator.
Electromechanical lubricators, on the other hand, rely on mechanical means to dispense the lubricant, and as such are more reliable and consistent in any given environment.Inherently, this technology has the added benefit of generating greater output pressures, which means greater flexibility in how and where they are used.Many come with various power options and are capable of being remote-mounted significant distances from the application point.In fact, we have several “cold temperature” customers that exploit this ability by mounting the lubrication system inside a building or heated enclosure, and then running a lube line to the outside lube point.
Power Source
When thinking about the proper setup for a cold temperature application the first thing I think about is the power supply to the lubricator. As alluded to, several options are available for powering mechanical lubricators such as:
In a typical cold temperature application, the simplest solution is to use a lubricator that is battery powered. Most automatic lubricator sales personnel would recommend lithium batteries in cold weather as well. Mechanical lubricators also come with the ability to be remotely mounted from its application (which is a great feature) but, getting the lubricator as close to the lube point as possible is best. With that said, directly mounting on the lube point is ideal for cold weather applications.
Memolub HPS - Pillow Block BearingThe Correct Lubricant
One of the most important (and at times, most difficult) issues to address in a cold temperature application is the lubricant.Finding a lubricant that not only meets the application’s needs, but also flows well at low temperatures can be quite an undertaking.With few exceptions, greases tend to resist flow as temperatures lower.A grease that flows like syrup at room temperature could flow like molasses at near-freezing temperatures.This resistance to flow is critical when using automatic lubrication devices, as the device will have to generate enough pressure to push this semi-solid to your lube point.Your average hand grease gun has a pressure output of 10,000psi, which is more than sufficient to push even the thickest of greases. In contrast, a typical self-contained mechanical lubricator generates somewhere in the neighborhood of 300-400psi, which is usually sufficient to push a light- to medium-weight grease at temperatures above freezing, but can be an issue at colder temperatures.Understanding how your lubricant’s flow is affected by cold temperatures is imperative and should not be taken lightly.
A good place to start finding the best lubricant for your application is the OEM (Original Equipment Manufacturer), but finding a lubricant that in addition is suitable for use in automatic lubricators requires some further consideration.It doesn’t matter how good the lubricant is for your application if it never reaches the intended lube point. Some important characteristics to look for are the base oil viscosity, grease consistency/thickener, and lubricant additives.
Base Oil Viscosity (ISO) is the measure of a fluid’s resistance to flow when under stress. This is probably the most important characteristic to speak of and is commonly confused with Grease Consistency, which is a measure its relative thickness. A greases consistency is characterized by its Thickener, which is responsible for keeping the lubricant intact on the lube point. The consistency is rated by an NLGI number on a scale from 000-to-6 where the higher the number, the thicker the lubricant. Lastly, substances added into the lubricant in order to enhance their performance are referred to as Lubricant Additives.
These variables make up the performance properties of a lubricant and the properties needed are determined by the application.In cold temperature applications it is very important to make sure that the lubricant can operate in a lubricator effectively.A good rule of thumb for this is the colder the application, the lower the NLGI weight and ISO numbers should be.To learn more about selecting lubricants read Step-by-Step Grease Selection found in Machinery Lubrication.
In Conclusion
Automatic lubricators are a great option to employ on your cold temperature applications; however, the success of properly lubricating your equipment comes down to carefully planning the setup of the application. Using an electromechanical lubricator with a lithium battery pack can produce a reliable and consistent result.Make sure to limit the distance between the lubricator and the lube point, and if at all possible, directly mount the lubricator for best results.Choose a lubricant with a lower NLGI weight and ISO number that is going to work in the lubricator as well as meeting your applications needs.Using an automatic lubricator on your cold weather application will not eliminate the need of checking on your lube point, but it will certainly limit the number of times you have to do it.It is important to note that automatic lubricators are pieces of equipment and do require monitoring and maintenance.
Sources:
Thibault, Ray. “Maintenance Technology: Grease Basics.” July 2009: n. pag. Web 7 Oct. 2011.
Noria Corporation. “Machinery Lubrication: Step-by-Step Grease Selection.” Sept. 2005: n.pag. Web. 7 Oct. 2011