I want to control opening and closing of an orifice depending on the flow in a downstream link. I want to close the orifice for 15min if the flow in the d/s exceeds say 50 LPS, after 15 min I want to check again the flow in the link and adjust the opening-closing of the orifice depending on the flow above-below 50LPS. How can I right a rule which can solve this problem?