A solenoid assembly for operating a plurality of pneumatic valves of a fluid delivery system and capable of supplying an uninterrupted flow of a fluid, the assembly comprising: a plurality of solenoid valves, wherein each solenoid valve is capable of being in an energized state and a de-energized state, each solenoid valve comprising: an internal pressure port in fluid communication with a first means to supply a pressurized inert gas; an internal actuator port in fluid communication with a respective pneumatic valve and with the internal pressure port when the solenoid valve is in an energized state; and an internal relief port in fluid communication with the internal actuator port when the solenoid valve is in a de-energized state; and a manifold upon which the plurality of solenoid valves is affixed, characterised in that the manifold is internally fluidly connected to each of the internal pressure port, the internal actuator port, and the internal relief port of each solenoid valve, and wherein the manifold comprises: an external pressure port in fluid communication with each internal pressure port of each solenoid valve; and a dedicated external relief port for each of the plurality of solenoid valves, wherein the dedicated external relief port is in fluid communication with the internal relief port of the respective solenoid valve such that, when one of the solenoid valves is de-energized, a second means to supply a pressurized inert gas can be connected to the external relief port and supply pressure to the respective pneumatic valve operated by that solenoid valve. a plurality of solenoid valves, wherein each solenoid valve is capable of being in an energized state and a de-energized state, each solenoid valve comprising: an internal pressure port in fluid communication with a first means to supply a pressurized inert gas; an internal actuator port in fluid communication with a respective pneumatic valve and with the internal pressure port when the solenoid valve is in an energized state; and an internal relief port in fluid communication with the internal actuator port when the solenoid valve is in a de-energized state; and an internal pressure port in fluid communication with a first means to supply a pressurized inert gas; an internal actuator port in fluid communication with a respective pneumatic valve and with the internal pressure port when the solenoid valve is in an energized state; and an internal relief port in fluid communication with the internal actuator port when the solenoid valve is in a de-energized state; and a manifold upon which the plurality of solenoid valves is affixed, characterised in that the manifold is internally fluidly connected to each of the internal pressure port, the internal actuator port, and the internal relief port of each solenoid valve, and wherein the manifold comprises: an external pressure port in fluid communication with each internal pressure port of each solenoid valve; and a dedicated external relief port for each of the plurality of solenoid valves, wherein the dedicated external relief port is in fluid communication with the internal relief port of the respective solenoid valve such that, when one of the solenoid valves is de-energized, a second means to supply a pressurized inert gas can be connected to the external relief port and supply pressure to the respective pneumatic valve operated by that solenoid valve. an external pressure port in fluid communication with each internal pressure port of each solenoid valve; and a dedicated external relief port for each of the plurality of solenoid valves, wherein the dedicated external relief port is in fluid communication with the internal relief port of the respective solenoid valve such that, when one of the solenoid valves is de-energized, a second means to supply a pressurized inert gas can be connected to the external relief port and supply pressure to the respective pneumatic valve operated by that solenoid valve.