Pure helium from a cylinder at high pressure was passed through a pressure-reduction gage into the humidifying unit (center). The pure helium was humidified by adding sufficient water vapor to produce a relative humidity of 25 to 35 percent. The proper humidity was achieved by passing the helium through distilled water maintained at a temperature of 4 degrees to 6 degrees Celsius. The insulated water bath in which the humidification tower was immersed was thermostatically controlled at the desired temperature. E. C. Cretiz of NBS Gas Chemistry Laboratory, shown, checking the temperature of the bath. The arched hose connected the humidifying unit to the gas compressor (on the right).
National Institute of Standards and Technology
National Institute of Standards and Technology