Abstract: A leak test system is disclosed for a double block and bleed valve arrangement, the system including a second vent valve disposed along the bleed line and a secondary gas supply line connected to the bleed line for introducing gas at a known pressure into the bleed line to test the valves and ensure that they are not leaking. A pressure transducer is positioned to monitor the pressure within the bleed line. The pressure transducer is in communication with a processor which generates an alarm if the pressure in the bleed line changes, thereby indicating a leak. A method for testing each valve in the arrangement is also disclosed.