A coolant system includes a multistage compressor having a plurality of surge detection sensors. A condenser is connected to an outlet of the multistage compressor. An economizer is connected to an outlet of the condenser and has a gaseous coolant outlet and a liquid coolant outlet. The liquid coolant outlet is connected to a cooler and the gaseous coolant outlet is connected to a second or later stage of the multistage compressor via a controllable valve. A controller is communicatively coupled to the surge detection sensors and the controllable valve. The controller includes a non-transitory medium storing instructions for causing the controller to detect an occurrence of a surge and restricting a flow through the controllable valve until the surge has ceased.

A coolant system includes a multistage compressor having a plurality of surge detection sensors. A condenser is connected to an outlet of the multistage compressor. An economizer is connected to an outlet of the condenser and has a gaseous coolant outlet and a liquid coolant outlet. The liquid coolant outlet is connected to a cooler and the gaseous coolant outlet is connected to a second or later stage of the multistage compressor via a controllable valve. A controller is communicatively coupled to the surge detection sensors and the controllable valve. The controller includes a non-transitory medium storing instructions for causing the controller to detect an occurrence of a surge and restricting a flow through the controllable valve until the surge has ceased.

A fuel pump system (100) and associated method for supplying fuel from an associated fluid source (112) to an associated downstream use (102, 104) including for engine (i) start mode, (ii) run mode, and (iii) actuation mode are disclosed. The system has a pump (110) including a primary stage (116) having an inlet (114), and an outlet (120) that is configured to selectively supply pressurized flow for the (ii) run mode, and a regenerative stage (130) commonly driven with the primary stage to selectively provide pressurized fluid for the (i) start mode and the (iii) actuation mode.