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TAPPI T 251 Air permeability

Standard:  

TAPPI

Method:

TAPPI T 251

Title:

Air permeability of porous paper, fabrics, and pulp handsheets

Scope and Summary

TAPPI T 251 Air permeability provides for evaluation of the air permeability of highly porous papers, other fiber webs and fabrics and for formation of special handsheets to evaluate the potential for development of this property in raw materials. The permeability is measured by determining air flow through the sheet at a specified pressure drop. The sheet formation is based on conventional procedures, with special provisions for handling sheets of low porosity.

Significance

Air permeability is an important property of filter papers, nonwoven fabrics and cloths of various kinds. This method is appropriate for materials which are too porous for testing by such methods as TAPPI T 460 “Air Resistance of Paper.” TAPPI T 251 was withdrawn by TAPPI in 1996. IPS follows the 1985 version of the method. However, IPS recommends ASTM D 737 as an alternative method.

Samples

To perform adequate testing, at least 5 sheets of paper, each about 6 in. square are required. For pulp samples, handsheets are made following TAPPI T 205.

 

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