A valve comprising: a valve housing including a fluid inlet and a fluid outlet (206,207) with a longitudinal axis defined through the valve housing; and a toggle mechanism configured and adapted to cycle flow from the fluid inlet to the fluid outlet through a plurality of different flow rates in response to repeated impulses, and to hold flow rate steady between impulses, wherein the toggle mechanism includes a solenoid operatively mounted to the valve housing surrounding an armature mounted within the solenoid for movement relative to the valve housing, wherein the solenoid is configured and adapted to provide impulse actuation to the armature for cycling the flow rates, and characterised in that the toggle mechanism comprises: an armature mounted within the valve housing for movement relative to the valve housing along the longitudinal axis; and a pintle mounted within the valve housing with an interior flow passage defined in the pintle in fluid communication with the fluid inlet of the valve housing, and a pintle outlet (250,251) for selective fluid communication between the interior flow passage of the pintle and the fluid outlet of the valve housing, wherein the pintle and armature are configured and adapted so that repeated impulse actuation of the armature along the longitudinal axis cycles the pintle between first and second rotational positions corresponding to first and second flow rates for fluid communication from the interior flow passage of the pintle to the fluid outlet of the valve housing. a valve housing including a fluid inlet and a fluid outlet (206,207) with a longitudinal axis defined through the valve housing; and a toggle mechanism configured and adapted to cycle flow from the fluid inlet to the fluid outlet through a plurality of different flow rates in response to repeated impulses, and to hold flow rate steady between impulses, wherein the toggle mechanism includes a solenoid operatively mounted to the valve housing surrounding an armature mounted within the solenoid for movement relative to the valve housing, wherein the solenoid is configured and adapted to provide impulse actuation to the armature for cycling the flow rates, and characterised in that the toggle mechanism comprises: an armature mounted within the valve housing for movement relative to the valve housing along the longitudinal axis; and a pintle mounted within the valve housing with an interior flow passage defined in the pintle in fluid communication with the fluid inlet of the valve housing, and a pintle outlet (250,251) for selective fluid communication between the interior flow passage of the pintle and the fluid outlet of the valve housing, wherein the pintle and armature are configured and adapted so that repeated impulse actuation of the armature along the longitudinal axis cycles the pintle between first and second rotational positions corresponding to first and second flow rates for fluid communication from the interior flow passage of the pintle to the fluid outlet of the valve housing. an armature mounted within the valve housing for movement relative to the valve housing along the longitudinal axis; and a pintle mounted within the valve housing with an interior flow passage defined in the pintle in fluid communication with the fluid inlet of the valve housing, and a pintle outlet (250,251) for selective fluid communication between the interior flow passage of the pintle and the fluid outlet of the valve housing, wherein the pintle and armature are configured and adapted so that repeated impulse actuation of the armature along the longitudinal axis cycles the pintle between first and second rotational positions corresponding to first and second flow rates for fluid communication from the interior flow passage of the pintle to the fluid outlet of the valve housing.