While conducting composition measurements on helium-hydrogen mixtures using a Varian gas chromatograph at WSU’s Analytical Chemistry Service Center, I discovered that the ratio of orthohydrogen–parahydrogen has a significant effect on the measurements.  An in depth discussion of the allotropic forms of hydrogen can be found in the previous post “Why equilibrium hydrogen doesn’t exist”.  In my system, gaseous hydrogen is condensed in a copper test cell at 20 K.  An ortho-para catalyst is placed in the bottom of the test cell to ensure all of the hydrogen is converted to parahydrogen. Helium gas is then introduced into the test cell to the desired pressure. The amount … » More …

Rubotherm IsoSORP instruments utilize a Magnetic Suspension Balance to provide highly accurate fluid density and sorption measurements. The system utilizes Archimedes’ principle to determine fluid density by suspending a sinker of known mass and volume in a fluid and measuring the weight with a precision balance. The applied force is transmitted to the balance by the magnetic suspension which decouples the testing fluid from the balance. The Rubotherm IsoSORP at Washington State University has recently been retrofitted for cryogenic temperatures and pressure up to 4000 psi. By placing the test cell in a vacuum chamber and thermally connecting it to a Cryomech cryocooler I have … » More …