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Reducing Pressure of Ammonia in a Storage Tank

IP.com Disclosure Number: IPCOM000091660D
Original Publication Date: 1968-Apr-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Knight, RD: AUTHOR

Abstract

In diazotype reproduction machines, the diazotype film or paper is developed by contacting the film or paper with ammonia gas. This ammonia gas is supplied in the machine from a tank in which the ammonia is maintained under pressure, normally 125 psig at 75 degrees F. Because the development process is carried out a pressure below 125 psig, it is necessary to lower the pressure through a gauge or some other device.

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Reducing Pressure of Ammonia in a Storage Tank

In diazotype reproduction machines, the diazotype film or paper is developed by contacting the film or paper with ammonia gas. This ammonia gas is supplied in the machine from a tank in which the ammonia is maintained under pressure, normally 125 psig at 75 degrees F. Because the development process is carried out a pressure below 125 psig, it is necessary to lower the pressure through a gauge or some other device.

The pressure in the tank can be lower than 125 psig if a solute, capable of lowering the vapor pressure of ammonia, is dissolved in the ammonia in an amount sufficient to form a saturated solution. The solute is selected so as to achieve the desired decomposition pressure of its compound with ammonia. This normally is the development pressure. For example, the addition of NaBr lowers the pressure of the ammonia in a tank from 125.3 psig at 75 degrees F. to 40 psig at 75 degrees F. Other possible solutes which are useful to achieve different pressures both above and below 40 psig are NaCl, NaI, LiCl, LiF, NH(4)SCN, and their mixtures.

The initial pressure of the ammonia in the tank, established by the addition of the solute, is maintained as the ammonia is removed from the tank for development by precipitation of the solute from the saturated ammonia solution. Thus, the solution retains its saturation and the initial pressure of ammonia is maintained.

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