Filtration Facts

Two-Stage Filtration Is A Best Practice In Many Situations

  

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Selecting the best tool and technique for a job is often a simple task. No one wants to waste time or be forced to "fix" something once it's been fixed already. As carpenters like to say "Measure twice, cut once." We always want to DO IT RIGHT THE FIRST TIME.

However, when it comes to filtering solids from water or other liquids, the wisest and most efficient method is sometimes a 2-step approach in which: 

1. Large particles or debris are removed in the "first pass" by one method or tool (the pre-filtration step)
2. Smaller particles are removed in a "2nd pass"

For small particle removal (Step 2), some type of barrier filter that catches tiny particles is often the tool of choice, such as bag filters and cartridge filters. But barrier filters get clogged and fill quickly when too many large particles are present -- thus the need for a pre-filter.

The pre-filter will:

(a) extend the life of the barrier filter, reducing usage and overall costs of purchasing filters and
(b) minimize labor time spent changing bags and cartridges

This is true in a wide variety of situations and applications, from turf and agriculture, to industry and more.

Example: Source Water From A River

Take, for example, a situation in which river water or sea water is used as the main source for an industrial water process. Quite often, debris of many shapes and sizes are present in the water, and no single type of filtration would remove large AND small solids very efficiently. Using a two or three-step process by taking out the larger debris and solids first with a low-maintenance solution is often used. This Step 1 can be some sort of large strainer or screen to keep large debris from entering the system, followed in Step 2 by a centrifugal separator to remove the other solids. If additional particle removal is required, some type of barrier filter could be used.

Agricultural and Irrigation Uses
There are similar applications in agricultural settings. Centrifugal separators can be used as pre-filtration to a drip irrigation system. In this situation the primary filtration concern is to keep the drip emitters from getting plugged, and sand media tank filters are most commonly used. However, a pre-filter can be used before the source water reaches the media tanks, reducing the number of backwash cycles the tanks must go through to keep operating efficiently. This backwash reduction system saves energy, water, and equipment.

Getting Tired Changing Barrier Filters?

Sometimes the original design of a filtration system consists solely of barrier filters, but maintenance staff grow tired of the constant bag and cartridge changes. When barrier filters are not changed as needed, pressure drops and other negative effects occur, and the system no longer operates within design parameters. Adding a centrifugal separator upstream of the bag filters is a perfect solution.

Want To Read More Details? Download Our Pre-Filtration Case Studies:   Read a couple of detailed Case Studies that explain pre-filtration in practice. Read how pre-filtration in a sugar mill reduced water waste and improved process efficiencies. And read how pre-filtration of river water prevents clogging of barrier filters at an oil production plant.