Expert Advice

Cartridge Grease Gun Refilling May Have Safety Risks
In the Expert Advice feature of the May 2007 issue, we published a tip submitted by a reader on eliminating cartridge changes with grease guns by drilling and tapping a port into the head of a cartridge grease gun and inserting a grease nipple (zerk fitting) and then filling the gun using a common air-powered grease pump. This is suggested to reduce the cost of the grease by purchasing in bulk and to reduce the risk of contamination of the grease during the transfer process into the gun. Since published, the tip has generated some comments from readers who have pointed out potential safety risks. After reading these comments and investigating the matter further, the editors of Machinery Lubrication magazine would like to offer the following precautions and remarks:

Many grease guns are designed with a "loader" fitting. This is a fitting on the head of the grease gun for filling the body of the gun from a bulk manual, low-pressure pump. It is instead recommended to purchase a grease gun that the manufacturer has designed specifically with a loader fitting. It is not recommended to replace the loader fitting with a regular zerk fitting for use with a high-pressure, high-displacement grease pumping system. The barrel of the grease gun was not designed to be filled at high pressure and this practice could possibly result in injury.

From the original tip provided in the May 2007 Expert Advice feature: converting the grease gun so that it can be refilled (loaded) from a bulk grease source via an air-powered pressure loading system, for the reason mentioned above, may weaken the metal structure resulting in rupture and the unsafe extrusion of grease. However, due to the fact that grease is not a compressible medium and the grease flow rate from the pumping system are relatively low, there is little likelihood of explosion or high-velocity metal fragments projecting from the grease gun.

The editors of ML would like to thank those readers who brought these concerns to our attention.

Leave It Hanging
To eliminate a possible contamination source when filling top-off containers, install a hook at the place where the containers are filled to hang the lid by its handle. This gives a clean place to put the lid, out of the way, with no chance of contamination.

I constructed the hook from 1/8-inch welding rod and made sure to remove sharp edges from both ends.