BAG FILTER HOUSINGS

INTRODUCTION :

If considering easy ways to filter particulate from liquids, consider using bag filter housings for your Application. That’s because bag filter housings are easy to install, service, use and perfect for a wide range of applications.

Bag filter housings are ideally suited when easy bag removal is advantageous because the liquid being filtered is messy or difficult to work with, as well as for process applications when quick and easy bag change-out is essential. Typical applications for bag filter housing include:

• Industrial water treatment

• Plating solutions

• Cooling towers

• Solvents

• Machine tool coolant

• Fuels

• Metal working

• Hydraulic fluids

• Paints

• Cutting fluids

• Oils

• Wastewater for sludge removal

• Edible oils

• Coatings

• Sludge

• Chemicals

• Food processing

• Process water

Bag filter housings are generally constructed of carbon steel—304 stainless,316 stainless and, on occasion, specialty metals such as Monel and Titanium are necessary. ASME code housings are

frequently specified in industrial applications,but non-code housings are typicallyused in commercial installations.

Bag Filter Housings Types :

Single, multi- and duplex bag filter housings are available, and housing requirements are based on flow rate and whether or not automation is necessary.

The four most common bag housings and bag sizes are shown below using industry standards.

Because bag filter housing are typically used in industrial applications, it’s common for them to be made using thick gauge steel with sturdy mounding legs, swingbolt lids, eye nuts, and stainless steel

strainer baskets for easy bag removal

Filter Bag Selection :

Filter bags come in a number of sizes, and they’re made in a variety of materials. Bag size selection is generally based on flow rate and capacity. The liquid to be filtered generally determines the materials of construction. Bag type is based on the application and the filtrationefficiency required.

Filtration efficiency is typically based on a particular micron (µm) rating to be removed, and efficiency may range from “zero” percent to 100 percent. Factors to consider before bag size,type and efficiency are selected as follows:

1. Flow rate,

2. TSS (total suspended solids),

3. Temperature,

4. Maximum pressure,

5. Pipe size for existing equipment,

6. Micron rating desired, and

7. Efficiency requirements.

Materials of construction

Chemical & Thermal Resistence of Bag Filter Medimum
MEDIA	MAX TEMPDEG C	WATER	SOLVENTS	MILD ALKALINE SOLUTION	STRONGALKALINE SOLUTION	MILD ACIDS	STRONG ACIDS
PP	90	☺		☺		☺	☺
PE	140	☺	☺	☺		☺
NYLON	160	☺	☺	☺	☺
PMO	90	☺		☺		☺
MMO	160	☺	☺	☺	☺
PTFE	200	☺	☺	☺	☺	☺

Filter bags are typically made using polypropylene felt (PP), polyester felt (PE), nylon felt (NY), polypropylene monofilament mesh (PMO), nylon monofilament mesh (NMO) and PTFE (PT).

Media selection is based on the factors listed above and the chemical and thermal Resistance.In the past, bag filters were considered coarse filtration when highly efficient filtration wasn’t required. In recent years, however, manufacturers of filter bags have developed more efficient products to meet market demands . now filter bags are available for precision filtration offering 100% retention efficiencies down to 1 micron.

One last consideration regarding bag filters is related to their limited surface area compared with cartridge filtration. For example, the most commonly used filter bag is the #2 bag, which is 7 inches (“) wide and 32” long. It has two sides, so the surface area of an entire #2 bag filter housing is about 3 square feet (sq. ft. or ft), or more if the bags are pleated or gusseted—a usually diamond-shaped or triangular insert in a seam to provide expansion or reinforcement.

As one can see from the data presented above, bag filters are convenient since they use a single filter bag. The filter area they provide is limited, how ever, compared to cartridge filtration Bag filters are an ideal alternative for general filtration requirements because they’re easy to install, service and use.