The Basics of Liquid Filtration
Why Filter?
Energy Conservation
Can minimize energy demand by sufficiently filtering heated or chilled water for reuse.
Quality
Prevent products from containing contaminants the can damage or ruin the product.
Equipment Protection
Filtration of coolants, oils, fuel and other liquids can greatly prolong the life of engines, and of most and other equipment. Filtration will also help reduce repair cost and down time.
Standardization
Proper filtration allows for a consistent product by removing chance particulate.
Pollution Reduction
Makes it possible to remove hazardous and prohibited materials before being discharged into a public waste water system.
Product Isolation
Can isolate solids produced of a liquid process.
Recycling of Materials
Filters can reclaim material used in manufacturing process such as silver from photo processing.
The Right System for You
Finding the right filtration system can be a tricky proposition. Our expert sales staff can assist you in finding the best filtration system for your individual needs. It is an important that requirements of the system are known so right equipment can be chosen. The three most important considerations to find the right filtration system for your needs are the following:
1. The most important is why you want to filter. Different systems excel at different facets of filtration. So, it is essential to define the main reasons you need filtration. That way equipment that best meets your goals can be chosen.
2. The second consideration is what liquid are you filtering. The liquids viscosity, acidity, temperature, flow rate, volatility, type of dissolved solids and several other factors are important to find the right equipment.
3. How fine you need to filter is the third consideration. Underfiltering is the most frequent problem in filtration. It can cause a host of problems. Overfiltering is also a problem that can hit the pocket book. If you are overfiltering you are paying more for the element, replacing the elements more often, and operating at higher pressure causes greater energy use. Series filtration is often a good economic solution. If you need to filter particles down to 1 micron but the vast majority of particles are 100 microns our greater it makes good sense to use series filtration. Putting a 1 micron filter downstream(after) a 100 micron filter avoids overloading the 1 micron filter and makes financial sense.
The Six Systems
Screens and Strainers
Screens and strainers are the simplest systems. A screen with a certain size opening stops all particles larger than the opening. Often gravity is the only force used to move the liquid. Since it only loads on the surface it can clog with solids quickly. There are back washing and mechanical cleaning systems that can extend the straining cycles.
| Initial expense | Med | Replacement Media | Low | Maintenance | Med | Labor | Med | Downtime | Low |
Plate and Frame Presses
Plate and Frame Presses are a series of plates held in a frame that create flirtation chambers where particles are collected by filter cloth. The yields a large filter surface. Plate and Frame Press are quite versatile and can handle high viscosity liquids and sticky particulate. The can be large and very expensive equipment. The should be a capital equipment. They extremely labor intensive.
| Initial expense | High | Replacement Media | Low | Maintenance | Low | Labor | High | Downtime | Low |
Bag Vessel Systems
A bag system is a highly adaptable. The liquid flows through the interior of the bag and flows outward trapping the particles behind in the bag. Single or multiple banks of bags can be used. The filter bags have a comparable long life and require little maintenance.
| Initial expense | Low | Replacement Media | Low | maintenance | Low | Labor | Low | Downtime | Low |
Cartridge Systems
Cartridge system are used for liquid cleaning and not solid collection. The liquid flows through the cartridge trapping the particulate. There are three main types of cartridges providing versatility. They are membrane, string wound, and bonded random fiber. Membrane cartridges collect contaminants on surface. Membrane cartridges provide absolute rated submicronic filtration. The makes them ideal final filters in series filtration. String wound and random fiber cartridges collect the depth of the filter media providing for greater dirt holding capacity. String wound function in the micronic range and are nominally rated. They are useful in low viscosity low solid loading applications. The random bonded cartridges are good for high solid loading and viscosities and are nominally rated. They are available in pleated and meltblown.
| Initial expense | Low | Replacement Media | Med | maintenance | Low | Labor | Med | Downtime | Low |
Rotary Drum Systems
In this system. a perforated drum wrapped in filter cloth is partially submerged in a liquid. Negative pressure in the drum draws the fluid through the drum. As the drum slowly turns the collect materials are removed from the section of the drum that is not submerged the the liquid. These systems work well in higher solid loading application but poorly with viscous liquids. They use a lot of floor space for the amount of filtration.
| Initial expense | High | Replacement Media | Med | maintenance | High | Labor | High | Downtime | Med |
Vacuum Belt Systems
This type of systems is generally useful for high solid loading applications. A loop of media passes a vacuum section where filtration takes place. The media then pass through a roller section that cleans off and collects the captured solids. This units have large footprint, are difficult to maintain, do not work with viscous liquids and are limit to 50 microns and above.
| Initial expense | High | Replacement Media | High | maintenance | High | Labor | Med | Downtime | Med |