Question

The permeability of a moulding sand was determined using a standard afs sample by passing 2000cc of air at a gage pressure of 10g/ square cm. If the time taken 1 point for the air to escape was 1 min ,the permeability no is

Answer 1

use formula,

$\eta=\frac{v\times h}{P\times a\times t}$

where $\eta$ denotes permeability number, v dennotes volume of air passing through specimen(in cm³) , h denotes height of specimen(in cm), P denotes difference between upper and lower surface of test specimen( in cm hg), a denotes cross sectional area of specimen and t denotes time in minutes.

here, v = 2000cc/cm³ , t = 1min, h = 5.08cm, P = 10g/cm² and a =6.4516cm²

so, $\eta$ = 2000 × 1/(10 × 6.4516 × 5.08 )

= 157.48

hence, permeability number is 157.48