Common compressor piston, rider ring, and packing ring materials perform well in oxygen service, but contain lead to achieve such results. With environmental legislation becoming more and more restrictive around the world, companies looking to remove lead from their processes have used lead-free materials, at the expense of operating hours, with many only lasting 4,000 hours in typical service.
CPI 138 material offers a lead-free alternative, developed to maximize compressor up-time
The customer fitted piston and rider rings in CPI 138 material on one of their oxygen compressors in mid-2013. A wear rate observation was made after 2,800 running hours, where no measurable wear was found. The compressor was put back into service and after more than 10,000 running hours, a second wear rate observation was made, which again showed practically no wear on the piston rings (0.53mm – approx. 7%) and no significant wear on the rider rings. The customer again placed the compressor back into service and continued to run until the rings had operated for a total of 16,000 hours at which point they chose to replace all consumables as part of a general service. The customer has continued to work with CPI on further technical solutions for their other oxygen compressors based on these positive results.
CPI 138 material represents a solution that is not only BAM-approved for use in oxygen service, but is also qualified by multiple air separation customers and OEMs and provides comparable service life to lead-based alternatives. It is also suitable for dry gases which contain oxygen as a constituent, such as bone-dry air and crude argon.