Plasma Cutting & Cartridges

This is the result from using our cartridge and fabric filter element inspection service.

1) It was not the cartridge that was normally supplied to clients.
2) It had an inverted cone reinforcement in the bottom closed end cap. We always recommend a flat closed end cap for maximum life. The pleat spacing was optimum for this kind of application.
3) The seals (gasket) were resilient which insures effective sealing between the clean air and dirty air compartments. The cartridge exhibited no evidence of improper installation or handling.
4) You could expect indefinite life on this filter element on all suitable applications with an advanced technology pulse jet cleaning system like ULTRA-FLOW.

This plasma cutting operation is quite common and we see many cartridges with problems from these operations. The dust generated is extremely fine and problems with seals and installation account for a big majority of problems. The other problem, that we see is that the settings on the cutting head are such that the dust can be prone to plasma coat the filter elements. The solution of the coating problem is to give the dust time to lose its reactivity before it reaches the filter media. None of these usual problems were evident on this filter element.

A) My first observation was the color of the coating on the filter. In cutting ferrous metal with a plasma arc cutter, the dust is black and coated with fine easily removed powder. In handling of these filter elements, we usually wear a mask because of the fine dust generated in the inspection process. In this case there was no dust generated in the procedure. The color of the coating was brown.

B) My second observation was that there was hard inflexible crust covering the dirty side of the pleats as if the element had been painted. It had the same strength as baked on auto finish.

C) The only time I previously observed this kind of coating on a cutting operation was when the plates were covered with some kind of coolant, cutting oil or pickled. On some cutters they use compressed air at the head. I would suggest checking the air line lubricant as a possible source of the binder that is creating this paint like coating.

Finally, a continuous coating of filter aid could be maintained on the surface of the filter media. The dust load is usually quite light and the coating might be about a 64th thick. The surface coating would be painted instead of the media. When the collector pulses the inert filter aid, coated with the paint, would be ejected into the collection hopper. How often to clean would be a judgment call. I would expect the cleaning and re coating every 2- 4 hours would be appropriate.

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