In the daily use of valves, various failures are often encountered. Valve leakage is the most common of many failures, and valve leakage generally includes internal leakage and external leakage! So, what is the difference between the two?

The internal leakage of the valve generally refers to the situation that the medium is still flowing out, leaking or dripping from the flow diameter outlet of the valve after the valve is completely closed. In layman’s terms, it is not tightly closed and the seal is not good! The cause of this failure is usually due to the erosion and wear of the medium or the inclusion of impurities. Even if the valve screw (valve stem) is tightened in place, since there is still a gap between the valve core and the valve body, the medium can still flow through.

The external leakage of the valve generally refers to the leakage of the medium in the external sealing part of the valve packing after the valve is completely closed or opened. That is, between the valve and the connecting flange or connecting thread, the sealing is not tight, which causes the medium to flow out of the connecting sealing surface, or the medium leakage caused by the weak sealing between the valve stem and the gland (ie the gland on the valve stem) , Or external leakage caused by trachoma on the valve body blank, and external leakage caused by the wear of the valve body due to medium erosion.