Selecting Side Stream Filtration

What are you filtering?

The most important factor of selecting side stream filtration is to understand what it is you are filtering and what you do not want to filter out. A few key items to pass along to the OEM or Distributor of the filter cart you select would be:

  • Lubricant Viscosity—High viscosity lubricants should not be pumped through fine filtration at high speeds due to air entrainment which results in cavitation and machine wear.
  • Lubricant OEM—Some lubricant manufacturers have heavier additive packages than others. Lubricants with high defoamant additives should not be filtered with sub-micron filtration.
  • Synthetic or Mineral Oil—Filter seal application is dependent on temperature, fluid type, and application.
  • Type of Fluid—Initial determination of filtration media will be taken into account dependent on the amount of water in the lubricant or if it is a water/oil invert lubricant.

What is the cleanliness spec?

The cleanliness spec is determined by the most critical component in the fluid path. Due to most contamination being microscopic, it is important to know the starting point and the ending point by using ISO 4406:99 reporting standards for particulate contamination and the filter micron and efficiency rating.

What flow rate do you need?

Depending on sump size and the amount of time you intend on having side stream filtration on the system, the flow rate should be calculated using the amount of fluid in the sump, the number of systems you want to filter and how many hours you have allocated to the filtering process. A general rule of thumb is to turn each reservoir’s total volume at least 7 times.

Example: If you have a 300-gallon reservoir and want to turn it 7 times in 1 hour, you would need a pump rate of 35 gallons per minute.

What filter do you need?

Generally speaking, there are 3 types of filters for solid and soft contamination. Each application is dependent on the efficiency and performance needed.

  • Synthetic Microglass filters have smaller pore sizes with a higher efficiency ratio than most other filters.
  • Synthetic media is less sensitive to moisture than cellulose or blown media and has a higher dirt holding capacity than other filters.
    • Baldwin has a study that shows contamination that plugs 50% of cellulose filters will only plug 10% of synthetic media allowing for higher flow rates.
  • Cellulose media is constructed of wood pulp and is a very economical means of filtration. We find that cellulose is less efficient than microglass but is very helpful when there is little water contamination in a reservoir that it would not be economical to run a fluid conditioner on.
  • Melt Blown Filtration—Only used in fuel filtration applications and has very good water separation characteristics.

This does not mean that if you have water contamination, you must select a cellulose media. There are many vendors out there that will impregnate a microglass filter with water absorbing media in order to handle the task at hand. It is very important to pull data based on lubricant analysis in order to acquire the most economical filtration Cart for your applications.

What should your filter cart contain?

If you do suspect you have a problem, or even if you just want peace of mind and simple want to check, here’s what you should do.

  • Correct pump application for your lubricant and cleanliness levels
  • Differential Pressure Indicators—Both, visual and electrical
  • Pre- and post-filter sampling ports
  • Fittings that are not open to the environment
  • Fittings that do not require penetration into the reservoir from the outside environment which could chip coatings in the reservoir, penetrate suction strainers or otherwise restrict flow to system pumps

For help selecting proper equipment or to rent a unit from PetrolinkUSA, visit our equipment rentals page or call 1-800-770-4510.