A rotational valve comprising a valve closure element , a shaft , at least one detection element , at least one detection means , and at least one first stop and at least one second stop, in which the shaft is linked to the valve closure element and the shaft can rotate between a closed position and a fully open position, each detection element comprises an aperture and an indicator element , the shaft extends through the aperture of at least one of the at least one detection element , the / each detection element is in sliding engagement with the shaft , and the shaft can rotate relative to the / each detection element , each indicator element can move between a first and a second indicator position , each indicator element abuts one of the at least one first stop when in the first indicator position and abuts one of the at least one second stop when in the second indicator position , each indicator element is associated with a detection means , each detection means can determine when its associated indicator element is in one of the first or second indicator positions , each detection element is configured to engage with the shaft via at least one engagement mechanism when the rotational position of the shaft relative to the shaft's closed position is in a predetermined angular range, wherein each engagement mechanism comprises a shaft engagement means associated with the shaft and a detection engagement means associated with one of the at least one detection element , engagement of the shaft and detection engagement means enables the shaft to transmit rotational torque to the detection element via the shaft and detection engagement means , and characterised in that , the shaft and detection engagement means are so configured that if rotation of the detection element is resisted by a force greater in magnitude than a disengagement force the shaft and detection engagement means will disengage from each other. the shaft is linked to the valve closure element and the shaft can rotate between a closed position and a fully open position, each detection element comprises an aperture and an indicator element , the shaft extends through the aperture of at least one of the at least one detection element , the / each detection element is in sliding engagement with the shaft , and the shaft can rotate relative to the / each detection element , each indicator element can move between a first and a second indicator position , each indicator element abuts one of the at least one first stop when in the first indicator position and abuts one of the at least one second stop when in the second indicator position , each indicator element is associated with a detection means , each detection means can determine when its associated indicator element is in one of the first or second indicator positions , each detection element is configured to engage with the shaft via at least one engagement mechanism when the rotational position of the shaft relative to the shaft's closed position is in a predetermined angular range, wherein each engagement mechanism comprises a shaft engagement means associated with the shaft and a detection engagement means associated with one of the at least one detection element , engagement of the shaft and detection engagement means enables the shaft to transmit rotational torque to the detection element via the shaft and detection engagement means , and characterised in that , the shaft and detection engagement means are so configured that if rotation of the detection element is resisted by a force greater in magnitude than a disengagement force the shaft and detection engagement means will disengage from each other. <EOS>