Because energy has a price, wasting energy means wasting money. Since filtration systems consume energy, they require maintenance and proper component selection to perform their best. Choosing high performing filters and housings will save money while ensuring protection from harmful contaminants. The following is what you need to know to make sure your filtration system is performing its best and conserving energy.
How Is Filter Performance Measured?
The performance of a filtration system is measured based on three key variables.
- Efficiency – The filter’s ability to trap contaminates of a certain type/size.
- Capacity – The amount of contaminate the filter can trap before it plugs and creates an unacceptable restriction to flow.
- Differential Pressure – The resistance to flow, based on the combination of the filter housing, element, and contaminate trapped in the filter.
The differential pressure (also commonly referred to as pressure drop, delta P, dP, ∆P) is the metric that is directly related to energy savings. All three of these variables are design trade-offs, and must be considered together when creating a well-engineered filtration system. An ideal system will have a high efficiency, a high capacity, and a low differential pressure.
What Is Pressure?
Pressure is a measure of the resistance to flow and potential energy density available to perform work. The relationship between work and pressure is shown below:
Pressure = Force / Area = Force • Distance / Area • Distance = Work / Volume
Since energy is expensive, it is desirable to have as much energy that is input into a system available to do useful work, such as transferring liquid products through tanks and pipes. And because pressure is a measure of available energy, we want to conserve as much as possible by using correctly sized filters and replacing them on a regular maintenance schedule.
What Is Differential Pressure?
Differential Pressure is simply the difference in pressure between two points in a fluid system. It describes the loss of energy available in a liquid or gas system; however, the energy isn’t lost in an absolute sense. Rather, energy is converted into thermal energy, which is unavailable to perform useful work.
Since all gases and liquids have mass, any directional change in flow results in a direction change with a corresponding differential pressure. Since all liquids and gasses have viscosity, all relative motion between the fluid and a pipe or ancillary device results in a certain degree of viscous or frictional differential pressure. As contaminant builds on a filter media, it reduces the amount of available flow paths, which is registered as an energy wasting pressure drop.
What Does Differential Pressure Tell Us?
Differential Pressure is measured either by an indicator on the filter housing itself, or by using an in-line gauge up-stream and downstream of the filter housing. It is a measure of all resistances to flow across the filter system and typically includes the loss through the orifices or ports, the resistance of the clean filter media, and the resistance of contaminants collected on the filter media.
Energy Savings Through Pressure Drop Reduction*
Changes in the differential pressure are an indication of physical changes in the filters. A sudden drop in differential pressure drop may alert us to a filter leak or rupture. As contaminants build on the filter, the pressure drop across the filter increases. Filters reaching terminal pressure drops should be serviced accordingly – either promptly changed out, cleaned or sterilized.
Choosing high quality components that are designed specifically to deliver the highest performance with the lowest pressure losses is a great way to provide energy savings while maintaining equipment
performance.
