If you intend using open-loop step response techniques to tune the anti-surge controller, it is helpful to know that the controller will take over if something causes the operating point to head towards surge. For example, if the manual override parameter MOR is disabled (as is normally the case) on a CCC controller, taking the compressor too close to the configured surge line will cause the controller to switch back to automatic and to step open the recycle valve. Although this will save the compressor from surge, it is also worth bearing in mind that the sudden movement of the recycle valve may have an adverse impact on the remaining gas system! So it