Direct touch operations

When all the sodium has dissolved, the phenoxide-phenol mixture is heated to 150°. With the oil bath or heating mantle still surrounding the flask, and with a protective shield between the reaction vessel and the operator (Note 3), the cold ethereal chloramine solution is added with rapid stirring in a thin stream from the dropping funnel at such a rate that the temperature of the reaction mixture does not drop below 125°. Best results are obtained if the thin stream of ether solution can be added directly to the molten mass without first touching the walls of the flask. 

Sample temperature is usually measured by a thermocouple placed as closely as is practicable beneath (52) or beside the sample holder, but it must not touch the suspended container. It may be possible to achieve closer proximity during null point balance operation because the sample holder is effectively stationary. It is alternatively possible to incorporate the sensor into the holder, even in direct contact with the sample, but the electrical leads (perhaps incorporated into the suspension) must not interfere with the working of the balance. The extension of TG measurements across wide temperature intervals (up to 120 to 2600 K) has been discussed by many authors (8,52,53). 

Direct labor is the labor expended to add value to the product, sometimes described as the cost related to individuals who touch the product. Process operators, assemblers, and inspectors are included in this area. 

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