Pressure blowdown system for oil injected rotary screw air compressor

A pressure blowdown system for an oil-injected rotary screw air compressor having an output conduit mounted to a high pressure side of the compressor and having a feedback conduit mounted to an intake side of the compressor, the system comprising:

• a rigid container having a gas reservoir therein, said container having a rigid plate mounted thereon closing said reservoir,
• a rigid valve housing mounted to said plate, said housing defining a valve spool cavity, said cavity having first and second opposite ends,
• a valve spool slidably snugly mounted in said cavity for sliding translation between said first and second ends of said cavity, respectively into first and second positions in said cavity,
• resilient means mounted in said cavity for resiliently urging said valve spool from said first end towards said second end of said cavity,
• a first gas passageway in said plate in unobstructed fluid communication between said first end of said cavity and the feedback conduit of the compressor,
• a second gas passageway in said plate in unobstructed fluid communication between said second end of said cavity and said gas reservoir, said gas reservoir in unobstructed fluid communication with the output conduit of the compressor,
• said housing having an exhaust aperture into said cavity so that said cavity is in fluid communication with ambient atmosphere when said exhaust aperture is not closed by said valve spool, said exhaust aperture positioned so as to be covered by said spool when translated into said first position in said cavity,
• said spool having a third gas passageway therethrough in fluid communication from said second end of said cavity to said exhaust aperture when said spool is in said second position, said spool when not in said second position sealing said exhaust aperture closed.