Vacuum valve and water seal valve are used in system of coagulating, taking out vacuum, and heater trapping, so as to ensure the efficiency of the machine set. The main difference between the vacuum valve and the water seal valve is that the water seal valve brings water of 0.5MPa in the stuffing box, which performs a water seal area upon and down the packing, soaks the packing stuff at the same time in order to ensure the stem packing can seal reliably.
Its characteristics are that the silicon grease to resist high temperature is injected in the isolation ring which is between the packing.

The test parameter are as following:
The vacuum degree??98KPa
The strictness of vacuum system??0.02KPa/min