TECH TALK
Ensuring Effective Filtration
Performance and Energy Savings
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.
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:
Force Force∙Distance
Work
Pressure = _____
= ____________ = ______
Area
Area∙Distance
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 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. 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. Call
Donaldson Compressed Air and Process Filtration for more
information.
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
ENERGY SAVINGS THROUGH PRESSURE DROP REDUCTION*
$6,000.00
$5,000.00
$4,000.00
$3,000.00
$2,000.00
$1,000.00
$0.00
0
2
3
4
5
PRESSURE DROP REDUCTION (PSI)
200 SCFM, 55 Hp
400 SCFM, 111 Hp
600 SCFM, 166 Hp
800 SCFM, 222 Hp
1000 SCFM, 277 Hp
** Savings based on energy cost of $0.13/Kw-Hr & 6000 Hy/Yr operation. Calculations based on
100psig/100F inlet conditions. Compressor assumed to be electric driven single stage with 63%
combined efficiency.
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Donaldson Company, Inc.
Compressed Air and Process Filtration
PO Box 1299, Minneapolis, MN
55440-1299 U.S.A.
[email protected]
DonaldsonProcessFilters.com
1
ality M
Qu
1. Efficiency – The filter’s ability to trap contaminates of a
certain type/size.
2. Capacity – The amount of contaminate the filter can trap
before it plugs and creates an unacceptable restriction
to flow.
3. Differential Pressure – The resistance to flow, based
on the combination of the filter housing, element, and
contaminate trapped in the filter.
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.
COST REDUCTION
HOW IS FILTER PERFORMANCE MEASURED?
The performance of a filtration system is measured based
on three key variables.
9001:2008
ISO
Standard No. 10-04*
Standard Number 10-04
Ensuring Effective Filtration Performance and Energy Savings (12/13)
© 2013 Donaldson Company, Inc. All Rights Reserved. Information in this document is subject to
change without notice.