The series FD flow detector, nominal size 12, detects a preset flow rate and can be used for various monitoring functions.
Meeting the safety requirements of EN ISO 13849 often requires fitting an upstream valve as a second shut-off route. Its diagnostic information is provided by a downstream pressure transducer. In this way, a safe shut-off is always possible. The one remaining loophole is where a directional valve jams in the operated position, a situation that cannot be detected until another, parallel-connected actuator is operated. This loophole can be closed with the flow detector, which is fitted downstream of the On/Off valve. When the On/Off valve is initially opened, there must be no significant flow. Next the respective directional valve should be operated.
Typically, the flow detector is used for mobile applications in which auxiliary actuators are supplied in parallel from one pressure source. This is required, for example, as a monitoring function for steering pumps in mobile machines.
