Q. Why do BHA-TEX® membrane filter bags operate at a lower pressure drop?A. The pressure drop across a filter bag almost always increases due to one of two reasons:1. Surface blinding caused by agglomeration of moist or sticky dust on the bag surface. 2. Depth penetration of fine particulate into the fabric, which cannot be removed during cleaning. BHA-TEX membrane nearly eliminates these two causes of high-pressure drop because of its microporous structure, ultra-high efficiency and dust-releasing properties. Q. At what emission requirement should I consider upgrading from my standard filter to the surface filtration provided by a bag laminated with BHA-TEX membrane?A. This is a tricky question since all emission levels are conditional upon inlet grain loading, filtration velocities, particle size and distribution and collector style. Generally emission requirements of less than 0.009 grains per cubic foot or below 20 mg. per cubic meter, may require a filter bag constructed with ePTFE membrane (BHA-TEX membrane) to achieve these levels on an ongoing basis. Dust populations with a significant percentage of particulate below 10 microns are especially difficult to maintain low outlet emission levels. Q. Will filter bag life be increased by using BHA-TEX membrane filter bags?A. BHA-TEX membrane filter bags can provide many years of operation and will usually provide a longer service life, however the current mode of bag failure must be analyzed on a case by case basis. BHA-TEX membrane filter bags rarely require replacement due to high pressure drop or low airflow. On the rare occasion of failure, ePTFE filters require replacement due to loss of strength of the base fabric which can be caused by mechanical wear, chemical attack, thermal breakdown or flex fatigue. Longer bag life can be achieved because the lower pressure drop provided by the ePTFE membrane allows for reduced cleaning, which reduces mechanical wear and flex fatigue. BHA-TEX membrane has been documented to increase filter bag life by up to five times in some installations. Q. Under what conditions should I consider switching from a polyester filter bag to a filter bag constructed from acrylic? (The same question applies to both ePTFE membrane as well as conventional polyester and acrylic filter bags.)A. Polyester can lose strength due to hydrolysis in atmospheres where moisture and heat are present. As a general rule of thumb hydrolysis does not become a major factor at temperatures below 212° F (100° C). The rate of hydrolysis increases exponentially as both heat and moisture levels increase. Applications with temperatures averaging above 230° F (110° C) and high moisture are especially vulnerable to moist heat hydrolysis. Please contact us for assistance analyzing your specific application. For More InformationCall: 800-821-2222GE 8800 East 63rd ST Kansas City, MO USA |