Abstract: An improved diaphragm type chemical dosing pumps can be designed as both a variable displacement accurate dosing pump and a fixed displacement accurate dosing pump. The improved dosing pump provides a required supply of pressurized fluid, to be called hereafter as process fluid, to an injection point against varying gas or liquid pressures. By eliminating the use of elastomeric sealing, the failing of the pump due to seal wear is eliminated. An internal pressure relief valve protects the pump mechanicals from premature failure. Use of a spring assisted suction assists positive suction for very accurate dosing. The working fluid is a driver fluid that is used to lubricate working components of the pump. The angled ports minimize friction losses to further improve pump efficiency and also eliminate building up of air pockets.