Tablets & Capsules

© Copyright Tablets & Capsules 2021 camfilapc.com 9 results based on true dust collector operating conditions. It not only an- alyzes how well the filters clean, but also how the collector performs as a whole. That enables manufacturers to make a much more accurate compar- ison when deciding which filters truly meet process needs. The Standard applies to "bag, car- tridge, or envelope industrial dust collectors that recondition the filter media by using a pulse of compressed air to discharge the dust cake from the filter media while the air cleaning de- vice remains on line." It prescribes a method for testing the performance of these dust collectors from inlet to outlet and in so doing accurately por- trays the dynamics of the equipment in multiple-filter arrangements, unlike the MERV method, which bases its comparison on the initial efficiency of a single filter. Multi-stage test sequence Under Standard 199, testing is a six- stage affair that challenges the dust collector just as a real-life application would (Figure 3). In Stage 1, dust is fed to the collec- tor at a specified rate—without pulse cleaning—until a specified differen- tial pressure is reached. In Stage 2, on-demand pulse cleaning commenc- es while the air flow and dust feed con- tinue for 4 hours. On-demand clean- ing conserves compressed air and maintains the filter pressure drop in a range that allows adequate air flow from the dust-generating process. It's the most common cleaning method used in the pharmaceutical industry. Stage 3 uses continuous pulse clean- ing while maintaining the air flow and dust feed. This stage lasts 24 hours or until the specified maximum differ- ential pressure is reached, whichever occurs first. The filters are cleaned at specified intervals, generally every 10 to 15 seconds. Stage 4 involves final dust loading with on-demand cleaning, while the air flow and dust feed are maintained for another 24 hours. Cleaning is trig- gered by high and low differential pressure setpoints that the dust col- lector manufacturer provides. Data collected over the final 4 hours of this stage are used to assess performance. Stage 5 simulates how the dust collec- tor would perform in an upset condi- tion. It calls for maintaining the dust feed while suspending pulse cleaning. This continues until the differential pressure reaches the specified maxi- mum, usually 10 inches water gauge. At that point, the dust feed stops. Stage 6 mimics a post-upset scenar- io. Air flow is reduced to 25 percent of the specified value, and continu- ous pulse cleaning runs for 10 cycles. The system is then returned to the specified air flow, and the differen- tial pressure is measured. Next, the dust feed is restarted and final mea- surements are taken. This stage rep- licates a process commonly known as "downtime cleaning." Figure 3

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