Safety On Line
Safety on line is a control line representing the distance from the surge limit line at which the safety on response will assume a surge has occurred and increase the surge control margin.
Surge Limit Line
Surge limit line is a line on compressor map representing the minimum flow below which the compressor will surge.
Recycle Trip Line
Recycle trip line defines an operating point beyond which recycle trip response will ratchet the control valve open.
Surge Control Line
Surge control line (SCL) defines the minimum distance between the operating point and surge limit line. As shown in figure SCL is always to the right to the SLL.
Tight Shut-Off Line
Tight shut-off line is a control line representing the minimum deviation for the tight shut-off response.
Surge control margine
The surge control margin (SCM) is the distance between SCL and SLL.