we have two sprayers, both 2 metres, one 3600 litres the other 4000, they both do the same work with the same nozzles at the same rates 200l/ha. The both have had liquid fertiliser through them.

The SP has a 6 cylinder diaphram pump, the trailed has a centrifugal pump.

The trailed can be loaded with the tractor at low idle, the sp needs quite a few revs on. The trailed has had, to my knowledge zero pump maintainance since it was new in 2008. The SP needs new diaphranms at least every other season because one of the fungicides with use disagrees with the rubber. One fungicide we refused to use has destroyed every rubber fitting, and all of the PWM nozzles on a lot of sprayers, the claims have been large.

I can see no benefit with a diaphram pump at all.