Hydraulics International air or gas driven pumps range from 4:1 to 900:1 with a drive air or gas range of 3 to 150 PSI. These pumps can start/stop/restart under full load and hold maximum pressure indefinitely. No electrical hazard in explosive or damp environments. Rated for water, oils, solvents, and most liquefied gases to high pressure. Simple maintenance and simple to control in fluid power circuits.