NOMEX filters offer one of the best total economies in a filtration
system because of higher air to cloth ratios, higher temperature
capability, and a long wear life.
High Temperature Resistant Nomex Needle Felt Aramid Needle Felt
1) Performs at high temperatures
NOMEX Needle Felt can be used continuously at operating
temperatures up to 218°C (425°F) , and can handle higher
temperature surges. However, to optimize bag wear life, continuous
temperatures of 204°C (400°F) and lower with minimum temperature
surges are recommended.
2) Resists flexing and abrasion
Flex resistance of NOMEX Needle Felt at room temperature is good,
about equal to that of polyester fibers; after aging at
temperatures of 121°C (250°F) and above its toughness if excellent.
Nomex needle felt should give more than three times the wear life
of polyester at 121°C (250°F) and above.
3) Effect of moisture
NOMEX® performs well at high operating temperatures with normal
amounts of moisture. The wear life projections in the below graphs
were developed using 6-10% H20. Higher levels of moisture and
temperature shorten wear life. When operating in high moisture
environments it would be worthwhile to investigate reduction of
temperature to reduce wear life. For example with 20% H20,
operating hours could be increased from 2,300 hours to 35,000 hours
(15X) by reducing the temperature from 204°C (400°F) to 148°C
4) Resists Chemicals
NOMEX aramid fiber resists attacks by mild acids, mild alkalis, and
most hydrocarbons. In addition customers report it to be unaffected
by fluorine compounds in gas effluent from metallurgical and rock
processing operations. In acid environments, evaluation of NOMEX
needle felt should be made to ensure that the fiber will perform
acceptably before insulation. NOMEX Needle Felt is an acid
environment, at temperatures above the dew point, will outperform
polyester. Temperatures above the dew point should be maintained to
minimize chemical attack on NOMEX Filter bags and the equipment.
The system should be warmed before putting on stream and dried
before being shut down to minimize chemical attack. To optimize bad
life when acid gases are present in the gas stream, the lowest
operating temperature that is safely above the dew point should be
used. Higher temperatures expedite chemical attack.
5) Dimensional Stability
NOMEX Needle Felt Nomex Filter bags is one of the most
dimensionally stable fibers available. Fibers of NOMEX properly
manufactured and finished, should neither stretch nor shrink over
2% when operated at temperatures up to 218°C (425°F).
6) High temperatures
The most effective use of NOMEX aramid is in high efficiency
filtering systems where effluent temperatures are above 250°F or in
systems with surges over 250°F. In hot gas filtration systems,
fabrics of NOMEX Needle Felt require less filter area, for equal
gas volume and efficiencies, than fiber glass.
The technical data of Nomex needled felt
Nomex needled felt
of 90 mins