Startup bypass system for a screw compressor

A method of operating an incompressible fluid flooded pump, said pump having an air end housing, said air end housing having twin screws said air end housing having an air or gas inlet port, discharge port and a working chamber, said inlet port leading into said working chamber and said discharge port leading out of said working chamber, said pump further has a working chamber bypass leading out of said working chamber, said twin screws are disposed in said working chamber, said working chamber bypass comprising a fluid passage inlet, a fluid passage outlet, a fluid channel, and a fluid flow control member, wherein, said fluid passage inlet provides an opening into said fluid channel from said working chamber, and said fluid passage outlet provides a fluid exit from said fluid channel, said method comprising:

• carrying incompressible fluid in said incompressible fluid flooded pump from said working chamber into said discharge port during a running mode of said pump;
• shutting down said incompressible fluid flooded pump after said pump enters said running mode without draining incompressible fluid from said working chamber;
• leaving the not drained incompressible fluid in said working chamber as a left amount of incompressible fluid;
• starting up said incompressible fluid flooded pump after shut down with said left amount of incompressible fluid in said working chamber and without draining said working chamber prior to start-up;
• allowing an amount of said left amount of incompressible fluid to flow from said working chamber through the working chamber bypass including the fluid passage inlet, the fluid channel, the fluid flow control member and the fluid passage outlet while said pump is in a start-up mode;
• making a groove of one of said twin screws adjacent said fluid passage inlet;
• prohibiting incompressible fluid which has flowed through the fluid passage inlet and fluid flow control member from flowing back into the working chamber;
• and
• prohibiting, generally, the flow of incompressible fluid to go from the working chamber and out the fluid passage outlet during said running mode of said pump.