With the aid of the HYDAC universal filling and testing apparatus FPU-1, bladder, piston and diaphragm accumulators are filled with nitrogen and/or the existing pre-filling pressure is checked and modified, respectively. Thanks to the wide product range of gas-side adapters to the accumulator and to the nitrogen bottle, HYDAC ensures the filling of practically all hydro-accumulators. An extensive product range of accessories, e.g. hoses, the pressure-reducing valve and also the case, can be assembled in accordance with customer preferences to round out the programme.