About Leakage of Metal Seat For Knife Gate Valve

Our metal seated Knife Gate Valve is made as per the specification of MSS SP-81.As we see, the article 10.2 of this standard specified the leakage rate of this valve,that means the valve’s seal leakage is allowable.

Through all the international manufacture designs of metal seated knife gate valve,disc seal need very big pressure ratio,but actually the seal can only offer little pressure ratio because the structure design,it too hard to fulfill,so caused seal leakage.

If the medium is dry ash,paper slurry,particle calcium carbide etc. self-seal flow.From the view of physics,the water molecules’ diameter is far smaller than dry ash and other composition of the flow.It’s more easier to across the micro tunnel of seal face,cause leakage.But the self-seal medium will jam the micro leakage tunnel automaticly under the pressure when the valve is closed,and this can reach the leakage rate of the national standard,and fulfill clients’ application.

So,we do not do seal tests,and shell hydraulic test only.