nozzle, with any excess head being tapped off by a bypass valve, as in [19]. This could however lead to interference between the tur- bine under test and the pump. A second option would be to use a header tank, varying the level between the free water surface of the header tank and the turbine unit. Although this solution is more representative of an installed pico hydro system, it would re- quire a large amount of space and causes repeatability and mea- surement issues. The alternative chosen, illustrated in Fig. 9, is to use a continuously fed header tank in a state of overflow in order to maintain a constant water level. The flow rate, and therefore the head at the exit of the nozzle, is varied using a throttle V1 and bypass valve V2. A flow meter is included in a horizontal pipe run to measure the flow rate. At the end of the horizontal run, a flexible pipe allows the nozzle angle to be varied without having to change any hardware in the system. The jet inclination angle can be varied through the adjustable nozzle support on the turbine system. The length of the pipework between components was specified to ensure the flow was fully developed for the important system components and physical constraints in the laboratory. From the specification of the flow meter, this required a straight run of pipe at least 5 diameters length before the flow meter, and 3 diameters after the flow meter [20], but to ensure the flow was completely developed by the time it arrived at the flow meter, the pipe was ex- tended to 50 diameters length [21]. The pipe between the flexible pipe and the nozzle was restricted to 10 diameters length due to physical constraints on the system.