EVR valves are commonly used to control the flow of exhaust gas. They also help to reduce NOx emissions. A number of factors should be considered before deploying an EVR valve. They are made up of various components and are able to be replaced with internal parts if they fail.
There are two main types of EVR valves. The first has a single air gap, while the second has a separate air gap. The main advantages of the 2nd generation valve are an extended sealing skirt and more consistent radial forces. It has a lower delivery profile to ensure precise implantation at the intended position. It has also been proven to decrease the rate of mild paravalvular regurgitation.
The EVR valve 12 and the vacuum regulator 14 are essentially two separate units, but they can be interconnected by tube connections. They are both able to be controlled by the electromagnetic solenoid assembly. This assembly contains the pinch valve manufacturers magnetic flux path including the armature member and a passageway that communicates with the atmosphere.
The armature 46 has a radially-spaced notches 86 along the peripheral edge. The armature is moved to either the open or closed valve positions by a preloaded armature spring. The armature is actuated by the force generated by the magnetic fluid. If the duty cycle is greater than 30%, the magnetic fluid is strong enough to lift the armature, and the valve is “open”. If the duty cycle is less than 30%, the magnetic fluid is not strong enough to lift the armature, so the valve is “closed”.
The electromagnetic solenoid assembly has the armature member positioned in the chamber 82, which is a controlling vacuum signal generator. The chamber has a diameter of 18F, which is smaller than the 22F of the sheath used for CV implantation. It is slightly cranial to the native annulus. This enables the EVR delivery system to deliver the prosthesis at the desired position 3-5 mm below the native annulus. The chamber 82 also contains a filtered air flow. The size of the openings is regulated to provide the necessary restrictive flow to balance the vacuum pressure.
The 2nd generation EVR valve has a new design that is slightly cranial to the native annulus. It has a smaller insertion and delivery profile to allow transfemoral access in patients with challenging anatomy. It has an extension sealing skirt to prevent paravalvular leaks, and it has an option to recapture. It has been reported to offer increased device success and higher patient survival rates.
The EVR valve is a viable alternative to the conventional flow regulator. In addition, it can be deployed without the need for de-soldering the valve. It is available in two sizes, and is suitable for a range of cooling capacities. It can be used in hot gas bypass applications and is suitable for use with refrigerants.
In addition, the vapor management valve is able to independently set the calibration points. The valve is also designed to inhibit purge flow below 20% of the duty cycle. These features eliminate the need for cumbersome calibration.