Adding new oil to a system is a common practice that can also yield high concentrations of contamination. Industry has no guidelines for new oil cleanliness which means that it may end up at your facility with an ISO cleanliness code of up to 23/20 or higher. Pre-filtering your new oil before it enters your system is an efficient way of minimizing the particle contamination and reducing the damage those particles will cause. Even opening the system fill port to add new oil is a cause for concern in many plant environments. Adapter manifolds are available that maintain a closed system, even when filtering the oil, for topping up the fluid or draining the tank.

Off-line filtration is an auxiliary form of filtration that is typically separate from other filters on a hydraulic or lubrication system. When properly engineered, some benefits of an off-line filtration system include:

It can be used to filter the first full tank of fluid to the desired cleanliness level before the main system pump is started.

The off-line system is not only capable of achieving a low level of contamination, but by using this system for topping-up, it can eliminate the dangers inherent to the normal methods of adding fluid.

Because changing the element doesn't involve touching the main system, a lower service skill for this function is acceptable.

Filter maintenance can be carried out at any time without stopping or introducing air into the main system.

By optimizing flow through the element, maximum dirt-holding capacity of the particular element can be fully utilized.

If the system is left running continuously, it provides a complete tank of super clean fluid ready for every startup.

The system will continue to clean up the fluid when variable delivery pumps are running at minimum displacement, and could be used to supply cool, clean oil to their casing under this condition.