Cascading water in a cooling tower is continuously scrubbing airborne contaminants from the atmosphere. The airborne contaminants in conjunction with particulates in the make up water find their way into the tower sump. These particles ultimately flow into the system accumulating in heat exchangers, condenser tubes, water cooled equipment and HVAC equipment.

Chemicals cannot remove dirt and filters and cannot control water chemistry. To keep your cooling water clean, both filtration and water chemistry must be effective. We will address the filtration side of the water equation with Miller-Leaman equipment.

If a filter is not used, expect the following problems:

1. Costly downtime for cleaning and repairs

2. Reduced operating efficiency

3. Increased maintenance costs

4. Quality control problems on production equipment

5. Increased chemical costs

6. Shortened equipment life

There are two basic approaches to filtering a cooling tower:

1. Full flow filtration continuously filters the entire system flow. As an example, a 100 ton system would have a flow rate of 300 gpm and a filter to handle this flow rate would be installed downstream of the pump.

2. Side stream filtration is done with a skid mounted filter and pump package which would draw from the tower sump on a continuous basis about 10% of the total system flow. In our example, the sump side stream rate filtered would be 30 gpm.

Each system has advantages and disadvantages. A sample of the tower water subjected to a particle count analysis is a good test to run to aid in the best choice. Contact us to arrange for a particle count test of your water.

A wide choice of equipment is offered to filter water and include:


Centrifugal separators

Disk filters

Sand media filters

Automatic screen filters

Bag filters

Diatomaceous earth (DE) filters

Point of use filters

Miller-Leaman offers two types of filtration equipment; strainers and disk filters.

Miller-Leaman strainers are made of an inverted conical heavy duty screen with the inlet water flow directed in an upward direction. As water enters the strainer, heavier particulate like sediment is accelerated downward into the debris reservoir at the base of the strainer. The accumulated particulate residue is then flushed from a bottom blow connection using system water pressure. The blow down can be done manually, by a timer, or by differential pressure controllers. Strainer screens are offered down to 50 micron particle size.

A disc filter is made of round plastic disc about the size of an old 45 RPM record. Each disc has small radial grooves on each side. The discs are then stacked together to form a filtration element. When the discs are compressed together, the cartridge is in filter mode. When the discs are unlocked, then the cartridge is in back wash mode. Two types of disc filters are offered; manual flush and automatic flush models. Each disc cartridge is inserted in a housing which then makes up a filter pod. The number of pods required is a function of the required flow.

Disc filters are capable of removing particles in the 10 to 200 micron range and are popular because they use very small quantities of water to back flush and clean the filter.

Disc filters are the state of the art replacement for sand media filters. With no sand to ever replace and about 95% less back flush water required to clean the filter, disc type filters are worth your consideration if you are frustrated with your current filtering equipment.

When selecting a water filtration system, there are many factors which should be considered.

1. Full flow or side stream flow?

2. What is the system flow rate?

3. What size particles need to be removed?

4. What are the particle characteristics; sediment, scale, plastic fines, algae, and other materials?

Miller-Leaman has laboratory equipment to do a particle count and analysis of your cooling water. Call us for more details on a water test and proposal to meet you needs