A method for regulating the speed of a compressor/vacuum element, said method comprising the steps of: - starting the compressor/vacuum element; - providing a pressure regulating valve on an influence channel, said influence channel being in direct fluid communication with the compressor/vacuum element; - said pressure regulating valve regulating the pressure within the compressor/vacuum element by adjusting the volume of fluid flowing between a process channel and the compressor/vacuum element relative to the difference between the pressure value within said compressor/vacuum element and a preset pressure value; characterized in that the method further comprises the steps of: - connecting the compressor/vacuum element to a process channel after the speed of the compressor/vacuum element reaches a preset speed value; and - sending a control signal to a motor driving the compressor/vacuum element for increasing or decreasing the rotational speed of the motor if current parameters relating to the current of the motor are not between a predetermined maximum and/or a minimum current value; - keeping the speed of the compressor/vacuum element relatively constant until the preset pressure value of the pressure regulating valve is reached; and after said pressure value is reached; - increasing the speed of the compressor/vacuum element in accordance with a predetermined second maximum speed variance graph; and/or - decreasing the speed of the compressor/vacuum element in accordance with a predetermined first maximum speed variance graph; whereby the method comprises the following step: - adjusting the speed of the compressor/vacuum element such that the power of the compressor/vacuum element is maintained at a relatively constant value. - starting the compressor/vacuum element; - providing a pressure regulating valve on an influence channel, said influence channel being in direct fluid communication with the compressor/vacuum element; - said pressure regulating valve regulating the pressure within the compressor/vacuum element by adjusting the volume of fluid flowing between a process channel and the compressor/vacuum element relative to the difference between the pressure value within said compressor/vacuum element and a preset pressure value; characterized in that the method further comprises the steps of: - connecting the compressor/vacuum element to a process channel after the speed of the compressor/vacuum element reaches a preset speed value; and - sending a control signal to a motor driving the compressor/vacuum element for increasing or decreasing the rotational speed of the motor if current parameters relating to the current of the motor are not between a predetermined maximum and/or a minimum current value; - keeping the speed of the compressor/vacuum element relatively constant until the preset pressure value of the pressure regulating valve is reached; and after said pressure value is reached; - increasing the speed of the compressor/vacuum element in accordance with a predetermined second maximum speed variance graph; and/or element in accordance with a predetermined second maximum speed variance graph; and/or - decreasing the speed of the compressor/vacuum element in accordance with a predetermined first maximum speed variance graph; whereby the method comprises the following step: element in accordance with a predetermined first maximum speed variance graph; whereby the method comprises the following step: - adjusting the speed of the compressor/vacuum element such that the power of the compressor/vacuum element is maintained at a relatively constant value.