There are a few rules to remember when sizing a filtration system:

  • With in-depth cartridge filters, the slower the flow, the more efficient the cartridge is and the longer the user can go between change-outs. At, we typically size housings to start out with a clean differential pressure of two pounds or less. You will find that many people in the filter business will quote housings that are undersized for an application so that they quote the lowest capital equipment cost.


  • The differential pressure (pressure drop) across both the cartridge and housing must be considered cumulatively. The pressure drop across the housing differs from housing to housing, but in most cases, it can be obtained from the housing manufacturer.


  • Assuming a cartridge vessel is designed for cartridges with a one-inch inside diameter, keep in mind that the flow through the bottom of each filter should not exceed 15-25 gallons per minute (for membrane pre-filters, try not to exceed 15 gpm). These flow rates should not be exceeded because turbulent flow is created on the interior core of the filter, which frequently cause unloading of contaminant from the filter media.


  • Always consider the viscosity of the material to be filtered when sizing filters or vessels. Also keep in mind that the viscosity of most materials varies depending on temperature. If you have an application where the customer does not want to go over a certain differential pressure and the temperature of the product can go through a wide swing, be careful to find out what the viscosity of the liquid is at both extremes of temperature.


Copyright 2008 Barney Corporation, Inc………1.614.274.9069




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We have been learning so much reading all about compressed air energy storage online at We sampled some of our favorite questions and answers from their FAQ page.

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Why do we need energy storage?

The primary benefits are:

Risk of Power Outages:  Today’s electricity grid is increasingly vulnerable to threats from nature, terrorists, and accidents.  Millions of American families and businesses are victimized by outages (both sustained and monentary) each year.  Power outages cost as much as $130 billion annually, while hitting the job-creating commercial and industrial sectors the hardest.

Saving Consumers Money:  Sixty million Americans in thirteen states plus Washington, DC are saving money because energy storage systems are providing frequency regulation in PJM territory (the power transmission operator in the mid-Atlantic region).  PJM has projected that a 10-20% reduction in its frequency regulation capacity procurement could result in $25 million to $50 million savings to consumers.  Energy storage can also let customers avoid premium pricing that utilities charge during times of peak demand.  That’s like getting a cheap airline flight on Thanksgiving or a rush-hour subway pass at an off-peakprice.

Clean Energy Integration and Energy Independence: Energy storage supports the integration of renewable energy generation.  Energy storage can also help cut emissions as it takes more of the load off fossil-fuel generation.  Peaking generation is one of the most costly and wasteful aspects of the grid, so making existing generation go further and avoiding capital and resource-intensive new facilities would make a significant contribution to our environmental priorities.  By supporting an all-of-the-above energy strategy, storage will also help accelerate our drive to energy independence.

Economy and Jobs: In addition to reducing economic losses from major and minor annual outages, experts say that energy storage will be a critical technology in the electricity grids of the future.  They also predict that the long term-health of the U.S. economy, and tens of thousands of future U.S. jobs, depend in no small part on the ability of U.S. companies to at least remain competitive, if not to become leaders, in this critical technology.

Compressors use off-peak electricity to fill the cavern with compressed air. For peak demand, the compressed air is withdrawn from the cavern and used to power a wind turbine. Credit: Ridge Energy Storage & Grid Services LP Read more at:

Compressors use off-peak electricity to fill the cavern with compressed air. For peak demand, the compressed air is withdrawn from the cavern and used to power a wind turbine. Credit: Ridge Energy Storage & Grid Services LP
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Is energy storage clean?

Yes. Energy storage has no direct emissions. It requires no pipelines. Its systems typically require a minimal footprint.  It recycles electricity.  But energy storage will also help cut emissions as it takes more of the load off traditional generation.

How big is the energy storage market?

Energy storage systems currently make up approximately 2% of U.S. generation capacity.  That percentage is growing significantly, especially with the advent of more renewable energy.  Pumped hydroelectric power has played an important part of our electricity grid since the 1930s.  Yet today, electricity from wind, solar and other ‘intermittant’ sources have created urgent needs for additional energy storage.
World-wide demand for grid-scale energy storage is estimated to reach over 185.4 gigawatt-hours (GWh) by 2017 – which is approximately the amount of electricity New York City consumes in 17 days.  That represents a $113.5 billion incremental revenue opportunity for an industry that currently generates sales of $50-60 billion a year.

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Advanced-adiabatic compressed air energy storage (AA-CAES) is an evolution of traditional CAES, designed to deliver higher efficiencies via a zero-carbon process. Operation is similar to traditional CAES in that energy is stored by compressing air with turbomachinery and storing in an underground cavern. The difference lies in the treatment of the heat of compression.

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Compressed Air Energy Storage (CAES) plants are largely equivalent to pumped-hydro power plants in terms of their applications, output and storage capacity. But, instead of pumping water from a lower to an upper pond during periods of excess power, in a CAES plant, ambient air is compressed and stored under pressure in an underground cavern. When electricity is required, the pressurized air is heated and expanded in an expansion turbine driving a generator for power production.

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