Equilibar® precision back pressure regulators are being used successfully in research reactor applications using supercritical fluids. Our EB1HP1 regulator is rated up to 5000 psig, giving scientists and engineers a new tool for precision pressure control with this fluid.
We typically recommend a SS316 diaphragm along with a SS316 body when specifying a pressure regulator for supercritical carbon dioxide. However, recent experimental results suggest that superior ultra low rate control can be achieved using PTFE/Glass diaphragms in a supercritical CO2 regulator.
Because supercritical carbon dioxide is a highly aggressive solvent, careful selection of seals and elastomers is key for good service life. Reductions in system pressure, even when not made in a rapid manner, can cause damage to many o-ring materials due to the exponential expansion of fluids permeated into the elastomers.
Several customers of Equilibar pressure control valves report that hydrogenated nitrile butadiene rubber (HNBR) o-rings are acceptable for their supercritical their service. HNBR is also referred to and sold as highly saturated nitrile (HSN).
Manufacturers of perfluroelastomers (FFKM) o-rings also recommend certain of their high-durometer (Shore A 90) varieties as being able to resist explosion decompression problems. DuPont’s Kalrez 0090 is specifically designed for rapid gas decompression service.
Application Success: Carbon Sequestration Research
The Equilibar precision back pressure regulator was used successfully to facilitate supercritical carbon dioxide research at the University of Sydney in Australia. Traditional pressure regulators with needle valve trims were not able to handle the ultra low flow rate and suffered from plugging problems. An Equilibar back pressure regulator with a supple PTFE/Glass diaphragm was able to provide stable control in this application and handle the phase changes.
See the white paper for details.
Contact our engineers to discuss your temperature, pressure, and fluid compatibility requirements so we can select the ideal o-ring and diaphragm for controlling supercritical CO2 pressure in your application.
For supercritical extraction applications, Equilibar has developed an improved blockage resistant regulator to avoid problems with icing and viscous oil fouling.
New Case Study: Equilibar back pressure regulator addresses critical challenges in supercritical CO2 research at Loughborough University ( download)