Can anybody clarify the valving/pump arrangement for a pump priming system which then supports the formation of siphon. I am looking for practical examples where this has been employed. We are also seeking advice on the pump type required. The flow rates are i teh order of 75 l/s but with mimimal head less than 6 metres.

You will want a self-priming pump with the capability to start with a suction head start capability of at least equal to your siphon height over the liuqid level plus some additional height as a safety factor.

You may want to consider a check valve in the suction line to help maintain the siphon flow and also an air vent valve in the discharge line to remove air previously contained in the siphon that will be displaced into the discharge line as the pump starts.

Of particular interest is the valving arrangement used to establish the siphon. I am looking for the pump to draw water from a lake ie it requires approximately 2 metres of suction lift and then for the pump to clear the line of air so that a siphon can be established and then for the pump to switch off and the system run as a siphon. At a first pass I had in mind a pump connected to an intake line with a bypass line the same diameter as the main line fitted across the pump with a check valve to allow flow out of the lake only. With such a bypass arrangement I am not sure whether the siphon would be maintained as the pump is siwtched off and I am looking for any past examples.

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