Terms & Forms
Helpful Terms
Abrasion
Wear on bags/cloth due to excessive bending, filtering, or product blasting.
Dewpoint/Acid Dewpoint
The temperature at which liquid condences in the bag house and or on the bag.
Bleeding/Bleed
Product particles or fume leaking (bleeding) through the bag.
Blinding
Product particles impacting filter media (bags) and closing the media pores reducing air (gas) glow and/or increasing pressufre drop in the system.
Bridging
Collected material build-up across an opening blocking airflow or cleaning. Example: Hopper outlet or between bags.
Cake
A layer of dust that is allowed to build up on the surface of the bag to enhance filtration. Generally this is only required on depth filtration style bags media.
Cloth
Sometimesn called media, medium or fabric. The compination of textile fibetrs to create a filtration cloth that will be converted into a filter bag.
Cloth Weight
Generally the weight per square yard of square foot of a specific cloth. Often used to identify weight and airflow characteristics for a cloth (media).
Gas to Cloth Ratio
Also called air to cloth ratio. The volume of gas (air) entering the dust collector (ACFM) the divided by the total square ft of the cloth area in the bag house filter section.
**How to figure total cloth area
(bag diameter (in.) x 3.14 x bag length (in))/144 x total number of bags
When doing calculations or ordering bags, please remenber these:
Circumference: distance around bag
Diameter: distance across a circle across a rounded bag or cage
Flat Measurement: across the bag laid flat
Particulate
Dust Particles
Permeability
Thge Measurement of the fabric's openess or porosity. Used when selecting proper media for filtration and operating pressures. CFM of Air/sq. ft. of fabric at 0.5" of H2O pressure differential.
Permeability Test
A test used on new materials for airflow as above. Also used on dirty filter bags to check blinding and and again on clean filters to measure the airflow aganst a new filter media airflow.
Pre-Coat
Materials added to the air stream on initial start-up and building initial dust cake. Some pre-coats include calcium dioxide, quicklime, burnt lime, perlite, diatomaceous earth, or a combination of these and other additives to assist the new bag.
Seeding
Inducing a coarse dry dust to the bags prior to full start-up. Similar to pre-coating, but sometimes done with process particulate (dust).
Shaker Bag House
Bags are cleaned by shaking during periods of down time or when no inloet air is present.
Snap Band
A flexible stainless steel band, covered in material. The snap band is found on the open end of a bag and snaps into a hole in the tube sheet section of the baghouse. This creates a seal between the dirty and clean sections in the baghouse.
Tensioning
The amount of tension applied to a shaker bag for propper operation and reduce wear. Rule of thumb is 2lbs. to 2.5lbs per circumerential inch of the bag.
Tube Sheet/Cell Plate
A tube sheet can be at either the top or bottom of a collector and is a fabricated metal sheet with close tolerance hole punched or laser cut to facilitate a bag snap band or bag and cage assembly.