A French plant had been struggling with frequent packing and ring replacements for one of their hydrogen chloride compressors. The HCl compressor was a Burckhardt 3-stage, tandem-piston, non-lube vertical unit with a discharge pressure of 30 bar (436 psi). Leakage across the piston rings and rapid ring wear had been causing a reduction in the throughput of the compressor. The customer had to replace rings and packing every 3 to 6 months. Gas flow from the machine would drop after only a few weeks following installation of replacement rings and packing.