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Gas Pressure Controllers

For more than 30 years, we develop electronics that optimize and simplify the use of our equipment. We present the most advanced instruments to monitor liquid cryogens and control cold-valves, furnaces, pressure cells...

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High Pressures

Automatic 0.2 GPa Gas Pressure Controller

The 2kbar Gas Pressure Controller supply continuously loaded high-pressure cells and Paris-Edinburgh presses with helium at a pressure ranging from 100 to 2 kbar (0.2 GPa). The gas is compressed with a standard single-stage diaphragm compressor from Nova-Swiss and stored in a buffer volume. The stabilization and ramps of pressure are performed with two innovative pneumatic valves patented by CNRS (patent #04 00 515). One valve is used to decrease the pressure and the other one to increase the pressure in the cell or press. They are actuated by a Eurotherm 2704 controller at a maximum rate of 30 bar per minute.

The operating principle of these novel valves is based on the elastic deformation of materials and is characterized by the absence of a stuffing box (0-ring). This is a real innovation for a flexible seal between the valve body and the needle stem is a source of many problems: leaks, pollution, and above all large friction effects requiring high force for opening/closing the valve and caus- ing large hysteresis.

The compressor, valves, controller and related electronics are packed in a crate that is easily moved to instruments. It also features two rollers of cables (380V and compressed air) and an external platform onto which a bottle of helium can safely be attached and exchanged. Remote operation is possible using the Modbus serial communication protocol (RS485 serial port or Ethernet).

Principle and safety aspects

After opening manually the helium bottle, a valve is automatically opened once the pressure delivered to the crate reaches 110 bar. A second valve is also opened when the pressure of the compressed air line reaches 6 bar. These two valves must be opened to put the crate into operation. The pressures are indicated on the synoptic.

The helium gas is filtered twice and goes through a check valve. It is then compressed with a Nova-Swiss 3 kbar single-stage diaphragm compressor. A high-pressure gauge located at the exit of the compressor returns the output pressure to the Eurotherm. The gas is stored in a buffer volume whose pressure is maintained 150 bar above the setpoint requested by the user. The Eurotherm controller opens the CNRS valve (VP1) to increase the pressure in the cell or press. It opens the CNRS valve (VP2) to decrease the pressure.

When there is an overload of pressure on the sample, a power cut, a compressed air cut or a lack of gas in the bottle, the low and high pressure circuits are automatically evacuated thanks to the valves operated by the mechanical pressure gauges. A 0.21 GPa relief valve located on the sample injection line and a kill switch complete the security system.