General's OLT Series tank mounted air compressors are integrally mounted on ASME air receivers to offer further ease of installation and versatility. All units are UL 2125 listed. Tank mounted units should always be used when an accelerator is required on the sprinkler system. Multiple dry valves may be supplied from a single tank mounted air compressor when using an AMD-1 UL / FM Approved air maintenance device on each individual system.