technical NOTES

*Generally operating pressure drop in case of RABH is 60-70 mmwg resulting
in further reduction in power consumption if proper sizing of bag house is
selected.
** Note: Operating cost shall be validated with present Condition.
5.7 Selection Criteria for Filter Bags
The selection bags and bag house technology should be considered based
on the following points.

• Long bag life so that the maintenance and shut down frequency is minimized.


• Low and stable pressure drop so that the power cost is minimized.


• Predictable performance so that bag changes can be planned.


• Low emissions so that pollution can be minimized and norms are met with.

The table-1 gives an idea for selection criteria for selection of various filter
bag fabric material.
Table-1

5.8 Cost Comparison
From the table 2 below, we can see that among the high temperature fabric
fiber glass fabric is the lowest cost fabric. This is very brittle and has low flex
durability hence this cannot be used in pulse jet filter bags. However, fiber

Fiber

Max.

Operating

temp.

Acid

Resistance

Alkali

Resistance

F l e x

Abrasion

Support

Combustion

Moisture

Resistance

Polyester needle

felt^130 Good Fair Good Yes Fair

Acrylic

Homo-Polymer^125 Good Fair Good Yes

Very

Good

Acrylic

Co-Polymer^110 Good Fair Good Yes Good

Fiber Glass

membrane^260 Fair Poor Poor No

Very

Good

Polypropylene

needle felt^90 Excellent Good Excellent Yes Fair

PTFE

membrane

(Polytetrafluoro-

ethylene Needle

felt)

260 Excellent Excellent Excellent No Excellent

Polyimide

needle felt

(P84)

260 Good Poor Excellent No Good