Compound injection holes are designed and compound injection valves are installed at locations of stem/cap and body support of side valve.When sealing of stem or seat is damaged to induce leakage,the compound can be used to do the second time sealing.A concealed check valve is installed in side of each compound injection valve to prevent compound from outflowing due to the action of transmitter substance.The top of the compound injection valve is the connector for fast connection with compound injection gun.