A spray nozzle body has an upper end provided with a clamp arrangement comprising upper and lower clamp halves tightly clamped onto a fluid supply tube having a preselected first diameter. A removable tubular fluid delivery stem is received in a receiver hole extending vertically into the nozzle body from a clamping surface of the lower clamp half and has an upper end portion tightly received in a fluid outlet hole, of preselected size, provided in the supply tube. The clamp arrangement may be reconfigured for being clamped onto a smaller fluid supply tube by providing a replacement upper clamp half and a pipe-size adapter, each having appropriately sized clamping surfaces, with the adapter being seated within the clamping surface of the lower clamp half. The pipe-size adapter incorporates a suitably dimensioned fluid delivery stem.