Difference between globe valve and needle valve
Needle valve is a kind of valve that can be adjusted, which has a wide range of uses, such as the cutting distance for flame cutting, and the knob for adjusting flame temperature is needle valve. Instrument needle valve is an important part of instrument measuring pipeline system, which mainly includes globe valve and ball valve, and its function is to open or cut off pipeline passage. The valve core of the needle valve is a very sharp cone, which is inserted into the seat like a needle.
The stop valve is also called a closed valve, which belongs to the forced sealing type valve. Therefore, when the valve is closed, it is necessary to apply pressure to the valve flap to force the sealing surface to not leak. When the medium enters the valve under the valve flap, the resistance required to be overcome by the operating force is the thrust force generated by the friction force of the valve rod and the packing and the pressure of the medium, and the force of the closing valve is larger than the force of the opening valve, so the diameter of the valve rod is large, otherwise, the failure of the top bending of the valve rod can occur.
1. The installation position, height, inlet and exit direction must meet the design requirements, note that the direction of medium flow should be consistent with the arrow direction marked by the valve body, and the connection should be firm and tight.
2. The appearance inspection must be carried out before the valve is installed. The nameplate of the valve shall meet the requirements of the current national standard gb 12220. For valves with working pressure greater than 1.0mpa and cutting off on the main pipe, strength and tight performance test shall be conducted before installation, and shall be used only after being qualified. During the strength test, the test pressure shall be 1.5 times of the nominal pressure, the duration shall not be less than 5min, and the valve casing and packing shall be free from leakage. During the leak test, the test pressure is 1.1 times the nominal pressure; the duration of the test shall be in accordance with the requirements of gb 50243.