Bag filters are a very simple technology that utilizes any of several types of materials, woven into a bag which is then typically placed into a porous metal basket. System flow passes into the upper side of the bag housing, through the bag (from inside out) and out the lower side or bottom of the housing. Contaminants are captured in the bag, requiring periodic shutdown or bypass in order to clean or replace the bag element.

Solids removal-Commonly ranging from 100 micron to 1 micron, bag filters can handle many types of contaminants, including heavy solids, floaters and organics. Some types achieve filtration performance in excess of their rating as a cake of solids forms on the bag’s lining. Ultra-fine bag elements are particularly subject to excessive replacement when the application also includes larger solids, resulting in excessive shutdowns, replacements & maintenance.

Flow range-Limited by the reasonable size and capacity of an individual bag element, most systems require multiple units and excessive manifolding for higher flow rates.

Pressure loss-Expect increasingly high pressure losses as the bag elements become loaded with contaminant. This subjects the downstream operation to undesirable and possibly unacceptable variable pressure and, eventually, potential loss of flow. Given the manual requirement for cleaning (automation not feasible) , constant monitoring or excessively high pressure losses must be anticipated.

Liquid loss-Relatively little, unless the user chooses to clean the bag elements, which then may result in significant liquid loss for cleaning (and maintenance, as well).

Solids handling-The advantage of solids concentration in a bag element is often offset by the bulk represented by the bag element itself. This can dramatically increase the overall volume of waste far beyond just the contaminant. And it complicates the disposability, scrap value or re-usability of the solids.

Replacement parts-Making the effort to re-use the filter bags is maintenance-intensive and wastes water. More common is the practice of disposing these bags … and replacing them. It is also routine to frequently replace the various a-rings and/or gaskets during the bag changing procedures. All of this requires that a stock of materials be maintained.

Maintenance requirements-There is no reasonable way to automate the bag replacement procedures. Either a bypass, duplicate filter or a system shutdown is required. It is a manpower routine (especially significant when multiple bag housings are involved) … subject to potentially being forgotten or performed at irregular intervals.

Space requirements-At the higher flow rates, larger bag housings and manifolds of multiple housings demand accessibility for bag changing routines, thereby requiring significantly more floor space than a LAKOS Separator.

When faced with solids separable by LAKOS in applications where the flow rate is steady enough for LAKOS, bag housings become a more maintenance/replacement/shutdown dependent alternative. If finer/floating solids are among the separable contaminants, LAKOS may be an effective pre-filter for a bag housing. Consider all the factors in your evaluation.