Williams/Milton Roy has expanded its range of pneumatically driven âWILROYâ? Chemical Dosing Pumps. The flow rate capabilities of each pump range from 0 â 2.08 litre/hour to 0 â9.18 litre/hour at a maximum discharge pressure of 3,000psi. The hydraulically actuated diaphragm head allows for an integral internal relief valve pressure control. The pump-head liquid end is maintenance free, with four main body sizings, each with two head size options. The pump body is constructed from AISI 316 stainless steel throughout with Gylon diaphragms, although several other liquid end materials are available, depending upon the chemical resistance of the wetted end materials. The liquid end is also offered with double diaphragm, leak detection and comes with alarm or pressure gauge rupture detection. The pumps can be air or gas driven with optional gas recovery. Ball check valves ensure high accuracy dosing, even at the smallest of flow rates.