When selecting a standard stop valve, the various non-metallic sealing materials used in the valve body should be suitable for refrigerants, lubricants, corresponding metal materials and mixtures, with good compatibility, otherwise it is difficult to ensure the performance and reliability of the valve. There are two installation methods for the stop valve. One of the advantages is that the media flows in the valve core, the root is not stressed when it is closed, and the root can be replaced when the valve is under pressure, which has the characteristics of long life. The other is that the media enters under the core of the valve. The disadvantage is that the driving torque is large, which is twice the upward flow. The valve axial force is large and the valve is easy to bend.
For the selection principle of the shut-off valve, it is generally applicable to manual shut-off valves with small diameters. When the shut-off valve is closed, the force of the medium on the spool is limited to less than 350 kg. The electric shut-off valve usually uses the medium to enter from above.
