Tamper-proof seals are installed on each filled drum; but these seals are NOT WEATHERPROOF. All lubricants should be stored inside a weatherproof structure which minimizes the temperature changes that occur from day to night. These temperature changes cause excessive “breathing” associated with moisture contamination in drums.
When a lubricant drum is warmed by sunlight or higher daytime temperatures, the fresh oil and air space inside the drum expands and creates enough pressure to force some of the air out through the bungs even though they may be sealed. Nighttime temperatures allow cooling, the product inside contracts, and a vacuum is created. Humid air, or free water itself, whichever is outside the bung at the time of the vacuum, can be sucked into the drum past
the bung seals. The water that was brought into the drum or the condensation from the humidity, settles out to the bottom of the drum and the lubricant is “wet.” This process continues as long as the storage conditions are not improved.
If it is impossible to store the drum indoors, the drum should be stored on its side with the bungs parallel to the ground. If it is not possible to store the drum on its side, place a block under one side to tilt the drum and at least keep water away from the bungs. These circumstances will minimize the “breathing” action that may lead to contamination.