As a requirement for testing and further development of a cooling system operating on the principle of magnetocaloric effect, we developed a double diaphragm reciprocating pump. The development of the pump derives from the geometric properties of a diaphragm collected from an existing available pump. We developed the casing of the pump on the basis of the desired working parameters of the pump and the theoretical calculations. We made the prototype of the pump using a 3D printer. We tested the prototype of the pump in three different hydraulic system setups. The third setup includes an active magnetic regenerator which is a key component of the cooling system. We compared the acquired results with the calculated results. We have noticed a beneficial influence of the use of the hydraulic accumulator on the stability of the pressures and flow of the system. Based on the results and findings, we provided with suggestions for improvements in further development of the pump.