"We have three new grease guns that are used to relubricate a variety of machine components, which require different greases. I recently was told that it is best practice for each grease gun to be dedicated to a single type of grease. Is this true? If so, what damage could result if a grease gun has held different types of greases?"
It is true that best practice suggests a grease gun be dedicated to a specific grease. In terms of potential damage resulting from using different greases in the same grease gun, the effects will be related more to the machine in which you are putting the grease than the grease gun itself.
Typically, the biggest concern is cross-contamination between greases. If a grease gun is not properly purged before greasing a component, there is a high probability of incompatibility between the greases, which can compromise the grease’s performance. Besides the possibility of cross-contamination, all grease guns can produce different amounts of grease per stroke even if they are the same make and model.
Best practice recommends that you calibrate each grease gun annually by pumping 10 shots of grease onto a postal scale and dividing the weight by 10. This will establish the average volume of grease per stroke. Next, label the grease gun with its average grams or ounces per stroke.
The reason for including this information on the grease gun is to ensure that you are achieving the correct amount of grease during relubrication. A proper regreasing procedure will reference the grease quantity in grams or ounces and not simply by the number of strokes.Use this calculator for determining grease volume and frequency.
Keep in mind that not only can all grease guns produce differing amounts of grease per stroke, but the same grease gun can generate varying amounts of grease per stroke if different greases are used, due to their unique formulation. Everything from the grease’s thickener type, base oil viscosity, additives and consistency can play a role in the grease’s pumpability.
In the event you already have used multiple greases in the same grease gun, you can still dedicate the grease gun to a specific grease without replacing it. If you choose to go this route, it is recommended that you thoroughly purge the grease gun to ensure all other greases have been removed.
Regardless of whether you decide to purchase new grease guns or dedicate your current models, you should label each gun with the grease to which it is dedicated by utilizing different colors, shapes and/or text.