A fluid mixing arrangement, referred to as a mixing block, for use in mixing two liquids like an acidic and a basic components of a cleaning solution, which is placed under pressure and sprayed through a conventional spray gun or nozzle at a reduced amount of pressure. In particular, the innovative design of the present invention provides the unique features of allowing manual and visual inspection of the various chambers, inlets, flow-rate or pressure reducing orifices, supply filters, and backflow preventing valves of the mixing block.