Features were introduced for several kinds of liqui d level measuring instruments commonly used for volatile medium in production of c hemical fertilizer;analysis centered on the encountered problems for different ial pressure liquid level gauges commonly used in the liquid level measurement o f liquid ammonia and ammonia water;the effective improvement measures were pre sented.

The concepts of the medium structure and structural coefficient of the finned heat exchanger were put forward in this paper.

Puts forward the concept of the medium structure and the structural coefficient of the finned heat exchangers, with a view to their performance optimisation and easier controlling.