| "We frequently use filter carts as a part of our contamination control program. Do you have any information about how long we should filter the oil using this type of filtration?" Off-line filtration is a powerful asset to the lube technician. Without interfering with the operation of the equipment, one can keep the oil clean with full-time off-line filtration, or periodically clean the oil with a portable rig, such as a filter cart. When using a filter cart, the oil is taken from a dirty sump, filtered and returned to the dirty sump. So the cleanliness of the filtered oil is diluted, so to speak, by the dirty oil residing in the tank. To overcome the dilution effect, the tank volume must pass through the filter approximately seven times to achieve the equivalent of single-pass filtration (where the oil is pumped from one container to another through a filter). For example, if you have a 30-gallon tank and a filter cart that pumps at five gpm, you need to run the cart for 42 minutes to equal single-pass filtration (30 gallons X 7, divided by 5 gpm). If you want to achieve two-pass filtration, you must engage the off-line filter for 82 minutes, or about 1.5 hours. Use this rule of thumb to manage scheduling activities where portable filtration is rotated from machine to machine within the plant. |
