The discontinuous carrier gas flow procedure

The steps of this procedure, devised by Nelsen and Eggertsen (1958) and modified by Atkins (1964) and Karp et al. (1972), are usually as follows  

Adsorbent sample is weighed in the flow-through adsorbent bulb or U-tube. 

Adsorbent outgassed by passage of carrier gas (e.g. He) or gas mixture (if not adsorbed at outgassing T). 

Adsorbent brought to operational T (usually 77 K), while gas mixture of known composition passes through sample (at rate of 10-50 cm3 min-1). 

Time allowed for adsorption equilibration as indicated by flowmeter signal. 

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The discontinuous gravimetric procedure 68 The discontinuous carrier gas flow procedure 69... 

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