Low pressure pneumatic surface safety control systems are desirable due to their less complex circuits. Low control pressures, however, are unable to open surface safety valves against high pressure unless large actuator cylinders are employed. Large pneumatic cylinders are often impractical due to wellhead space constraints. New compact actuators that provide the greatest amount of force at the point in the valve stroke where the resistant forces are greatest can be utilized to take advantage of low control pressures. The double-piston action of compact pneumatic actuators can also reduce the potentially damaging forces acting on the bonnet and gate during the opening cycle.

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