b'Reference Information / Measuring a Filter BagA large number of collectors operating today have been in service for 10 years or more. New permit applications are often difficult to obtain. They have forced existing baghouses to be modified and upgraded, changing the OEM configuration of the filters. To obtain replacement filters for these units is not as simple as looking on the side of the collector for a part number or pulling the original print. It is always better to confirm any part numbers that you may have on a filter bag or the baghouse with actual measurements of the bag. Usually, if there are spare bags that have not been installed, obtaining a sample to measure is simple. If all available bags are already in the collector, a used bag will do. Be aware of the type of dust you are dealing with when handling a used bag and take appropriate precautions such as gloves and respiratory equipment, if necessary. A bag pulled directly from the collector is your most reliable source simply because you can be certain it was in and functioning. Bags pulled from stock or from a pile of used bags may be mistakenly attributed to the wrong collector if the site has various dust collectors. Measuring is fairly straightforward for most bags. You want to get the diameter and the length of the bag, then physical descriptions of the end constructions. Lets start with the diameter measurement:DiameterThe diameter of the bag is important for both the fit and proper functioning of the bag. For instance, on pulse-jet filters (those with an inner cage) the relation of the bag diameter to the cage diameter has a direct influence on both bag life and the ability to clean down the filter. Too big a differential and the bag will wear quickly and force dust through the media (bleeding), too tight and the dust cake does not release sufficiently leading to high pressure drop, high fan load, and low suction at the pickup point in your system. Begin by placing the bag on a flat surface and flatten the bag out. Measure across the flat width of the bag for an edge to edge measurement. Take this measurement as near to the Measure flat width of bag opening of the bag as practical. Now to convert the flat width to bag diameter simply multiply: Bag flat width x 23.1415 = Bag DiameterLengthThe length of the bag is usually determined as the distance from top edge of stitch to attachment point. This may be different than the (OAL) overall length. For example see the Measure length from topimage at the bottom of the page. Here you see a measurement from the center groove of the edge of stitch snap ring to the disc bottom. Pull bag tight to measure entire length along the seam.to attachment pointMeasurements should always be made with the bag under slight tension (center of snap ring) (most bags 10 lbs, glass reverse-air bags 30-50 lbs typically). The measurement should be taken at the longitudinal seam if possible as this is the shortest part of the bag. Try for 1/4 increments. If there is any rounding of the measure always round up. A long bag is better than a short bag. www.standardfilter.com1.800.634.58371.760.929.8559 25'