[MCLENNAN] LIQUEFACTION OF HYDROGEN" 33 



IV. The Liquéfier and Subsidiary Heat Exchangers 



The arrangement of the liquéfier and the subsidiary heat ex- 

 changers is shown in Plate II. The coils B, C, D, F, I, were those 

 usually supplied by the British Oxygen Co., Westminster, for the 

 small Hampson Liquid Air machines made by them. The coil A was 

 made up on similar lines, but was about half as long as the others. 



The compressed hydrogen was first passed through the coil A, 

 and from there it went in part through the coil B and in part through 

 the coil C, from these two it wa:s passed in turn through the coils 

 D, F and I to the expansion nozzle H . S, a double walled cylinder 

 surrounding the silvered vacuum flask that contained the expansion 

 coil I, acted as a jacket to screen off" the admission of heat to the 

 latter. 



The cylinder V, surrounding the coil D, was kept filled with 

 liquid air supplied through the valve 2 from the reservoir "a." S 

 was kept filled with liquid air through the valve 3 from "a." 



The vessel E, which was a double-walled vacuum flask made up 

 by Messrs. Siebe, Gorman, Westminster, was supplied with liquid 

 aireither through the valve 4, the funnel L or directly from the liquid 

 air machine. 



The cylinder X surrounding the coil F was supplied with liquid 

 air from the vessel E or through the funnel K. The float gauges Pi 

 and Po were used to tell the height of the liquid air in the vessels 

 E and X respectively. 



The vessel X was connected by means of piping arranged as 

 shown in the plate to an eight horse-power vacuum pump of the 

 Reavell type. 



By exhaustion with this pump the liquid air in the vessel X was 

 made to boil under a pressure of a few centimetres of mercury. 



As regards the exchange of heat it will be seen from the diagram 

 that the hydrogen in the coil A was cooled by the air which evaporated 

 at atmospheric pressure from the liquid air in the vessels V and S. 

 The hydrogen in the coil B was cooled by the air which came from the 

 liquid air in X boiling under low pressure and that in the coil C by 

 the unused hydrogen which issued from the nozzle H or by that 

 which evaporated from the liquid hydrogen collected in the vacuum 

 vessel R placed within the lower part of the jacket S. The hydrogen 

 in the coils D and F was, of course, cooled directly by the liquid air 

 surrounding them. As the liquid air in X was kept boiling at a very 

 low pressure it followed that the hydrogen which passed from the 



