Another method of mixing at least two gases is provided. This method includes providing a mixture composition control, comprising a predetermined composition input and a composition trim input. Providing N gas flow meters, wherein N is 3 or more. Configuring the N flow meters to adjust the N gas flows to maintain the line pressure at a predetermined value, while maintaining the predetermined composition. Adding the N measured gas flow, thereby determining the total gas flow at the first predetermined intervals of time. Adjusting the composition trim input to vary the composition of the mixed gas, without modifying the predetermined composition input. And sounding an alarm, and/or terminating both the N gas flows, if either of the following exceed a predetermined range value: the instantaneous calculated theoretical percentage for any of the N gas flows, or the cumulative calculated theoretical percentage for any of the N gas flows.

A handheld system includes a reference pressure source configured to generate a reference pressure. The handheld system also includes a primary pressure source coupled to the reference pressure source. The primary pressure source is configured to generate a primary pressure in a primary pressure range. The primary pressure is less than the reference pressure, and the primary pressure is induced by the reference pressure source. The handheld system also includes a secondary pressure source coupled to the primary pressure source. The secondary pressure source is configured to generate a secondary pressure in a secondary pressure range. The secondary pressure is less than the primary pressure, and the secondary pressure is induced by the primary pressure source.

A hydraulic control device with a pressure control valve that has a control piston and a modulating piston which can move relative to one another. The control piston and the modulating piston are pushed apart from one another by at least one spring. At one end face of the modulating piston there is arranged a pressure chamber in such a manner that when the pressure chamber is filled, the modulating piston is caused to move in the direction toward the control piston. The pressure chamber can be filled by a first volume flow Q1 of a pressure medium. A venting line, with at least one further throttle, is connected to the pressure chamber. A second volume flow Q2 can be discharged, via the venting line, from the pressure chamber, The hydraulic control device can be utilized in a marine transmission,

A method of mixing at least two gases is provided. This method includes providing a mixture composition control, including a predetermined composition input and a composition trim input. Providing N gas flow meters, including a N gas flows, and N desired gas flow rates determined by the mixture composition control, wherein N is 3 or more. Mixing the N gas flows, thereby producing a mixed gas flow at the predetermined composition and at a line pressure. Configuring the N flow meters to adjust the N gas flows to maintain the line pressure at a predetermined value, while maintaining the predetermined composition. And adjusting the composition trim input to vary the composition of the mixed gas, without modifying the predetermined composition input.

A pressure control system may include a plurality of inflatable objects, each of the inflatable objects having a respective pressure sensor and a respective inflation valve, wherein each of the inflation valves has a behavior profile predictive of an amount of current used by the valve when operated. A valve controller of the system may have a pressure management circuit that receives information from the pressure sensors and is configured to automatically maintain a respective selected pressure in each of the inflatable objects by issuing commands to operate the inflation valves. An electrical current management circuit of the valve controller may be configured to predict, based on the valve behavior profiles, what effect the command would have on a total current usage, when executed, and automatically prevent any command that would cause the total current usage to exceed a maximum allowable current.

Animal drinking troughs have pressure reducers for reducing the higher pressure of the liquid supply to a low liquid pressure for supplying the animal drinking troughs. For various reasons, it is desired to change the reduced pressure. This takes place by adjustment of the pressure reducers. It is known to undertake such an adjustment with compressed air. This requires a separate compressed air source and a corresponding pipe system. The invention makes provision to adjust the pressure reducer hydraulically by means of the higher pressure of the liquid of the liquid supply. The energy required for adjusting the pressure reducers thereby provides the liquid pressure of the liquid supply. As a result, the pressure reducers according to the invention operate autonomously. A separate energy source for adjusting the pressure reducers is not required.

According to an embodiment, a variable pressure device includes a channel constituting unit and a switch valve mechanism. The channel constituting unit constitutes a channel including a first regulator and second regulators that are arranged in series to the first regulator and are in parallel to one another. The switch valve mechanism selectively connects the second regulators to the first regulator. Opening areas of the second regulators are different from one another.

A counter pressure valve arrangement for controlling a pressure level of a hydraulic fluid in a return line from a hydraulic actuator arrangement. The counter pressure valve arrangement comprises a counter pressure valve having: a moveable valve member; a counter pressure regulating port configured for being connected to the hydraulic actuator arrangement via the return line; a tank port configured for being connected to a tank or low pressure reservoir for storing low pressure hydraulic fluid; and a pump port configured for being connected to a source of pressurised hydraulic fluid. A first position of the valve member effects fluid communication between the pump port and the counter pressure regulating port for supplying pressurised hydraulic fluid to the return line (4), and a second position of the valve member effects fluid communication between the counter pressure regulating port and the tank port for discharging hydraulic fluid from the return line to the tank.

A counter pressure valve arrangement for controlling a pressure level of a hydraulic fluid in a return line from a hydraulic actuator arrangement. The counter pressure valve arrangement comprises a counter pressure valve having: a moveable valve member; a counter pressure regulating port configured for being connected to the hydraulic actuator arrangement via the return line; a tank port configured for being connected to a tank or low pressure reservoir for storing low pressure hydraulic fluid; and a pump port configured for being connected to a source of pressurised hydraulic fluid. A first position of the valve member effects fluid communication between the pump port and the counter pressure regulating port for supplying pressurised hydraulic fluid to the return line, and a second position of the valve member effects fluid communication between the counter pressure regulating port and the tank port for discharging hydraulic fluid from the return line to the tank.

A control system for controlling the down pressure applied to a soil-engaging component of an agricultural implement includes a down pressure actuator coupled to the soil-engaging component, and an energy storage device and a piston-containing cylinder are coupled to each other by a system containing pressurized fluid. A check valve is coupled between the energy storage device and the down pressure actuator to control the flow of the pressurized fluid from the energy storage device to the cylinder. A controllable relief valve and variable orifice are coupled between the down pressure actuator and the energy storage device to control the flow of the pressurized fluid from the cylinder to the energy storage device. A controller supplies control signals to the relief valve and variable orifice to control the flow of the pressurized fluid from the cylinder to the energy storage device based on the pressure of the pressurized fluid.