Mark A. DeSorbo
NEW YORK-An instrument that applies stresses on filter samples to determine and fine tune pore characteristics has caught the eye of the American Filtration and Separation Society (North Port, AL).
Manufactured by Porous Materials Inc. (Ithaca, NY), the automated compression porometer was unanimously selected by the 10 society judges for the New Product Award in March at its Annual Technical Conference in Myrtle Beach, SC.
The unique ability of the porometer is that it can test under simulated, yet true, process conditions, Dr. Krishna M. Gupta, technical director for Porous Materials, said in an interview with CleanRooms magazine during Interphex 2000, held here in March.
“It measures filter porosity. Big companies can use this instrument before installing filters in cleanrooms, and it's also a useful tool for researching and developing better filters,” Dr. Gupta explains.
 A porometer, manufactured by Porous Materials Inc. (Ithaca, NY) was selected for the American Filtration and Separation Society New Product Award. |
The instrument, he says, is capable of measuring a wide variety of properties of the filter such as the bubble point, mean flow pore size, pore size distribution, gas and liquid permeability and surface area, both in the presence and absence of stress. “The porometer tests the filter material, not the way it is produced. That's the advantage because you want to know how a filter behaves in a true situation,” Dr. Gupta says.
Operation, he says, is very simple. Liquid is used to fill the pores of a sample filter. Gas pressure on one side of the filter is increased to remove the liquid from pores. Recorded gas flow rates through wet and dry samples are used to evaluate all the material properties. The Windows-based porometer automatically increases, decreases or removes stress smoothly in predetermined amounts, which could be as small as 0.1 pound per square inch (PSI) up to 1,000 PSI. The instrument may be programmed to apply load and execute the test automatically without supervision.
Ray Collins, a vice chair of the society's executive committee and a senior specialist in solid-liquid separations for Dow Chemical Co.'s Engineering Sciences Laboratory (Midland, MI), uses the porometer in his research.
“I'm using this to gauge relative performance in our product development as well as in applications. I got in to it primarily to troubleshoot and understand why filter media performs the way it does,” Collins says.
Dow, he explains, has used a similar device that was made by Porous Materials, but it did not provide the range of measurements needed to calculate high-flow rate permeability and rate samples that are larger than normal or unusually shaped.
“The thing that is most appealing about the (new) porometer is that Porous Materials will modify the design to meet our needs,” Collins adds.
At the time of this report, Collins explains that it was too soon to judge the validity of the results, having used the instrument for only a month. “We anticipate that we will use it daily for the next year. Some aspects of the design need to be refined and PMI is working for this,” he says. “It has already proven to be a versatile and promising device.”