Safety valve and system for hydrocarbon storage tanks

A safety system for a hydrocarbon storage tank having a floating roof, a water drain in said roof, a drain opening from said tank, and a flexible line connecting said roof drain to said tank drain for carrying off rain water collected on said floating roof and preventing leakage of hydrocarbon liquid and through said tank drain, said system comprising;

• an electrically-operated, normally-closed valve means connected to said tank drain,
• means responsive to the electrical conductivity of liquid on the inlet side of said valve means to detect the presence of water therein,
• electric circuit means interconnecting said conductivity-responsive means and said electrically-operated valve means and operable to energize said valve means to open the same on detection of the presence of water in the inlet thereto,
• a primary power supply for operating said valve means,
• a secondary power supply operative in responsive to the failure of said primary power supply for operating said valve means, and
• an external power source for continuously charging said primary and secondary power supply.

A safety valve apparatus for use in a system for a hydrocarbon storage tank having a floating roof, a water drain in said roof, a drain opening from said tank, and a flexible line connecting said roof drain to said tank drain for carrying off rain water collected on said floating roof and preventing leakage of hydrocarbon liquid and through said tank drain, said apparatus comprising;

• an electrically-operated, normally-closed valve means adapted to be connected in said tank drain,
• means responsive to pressure in said system exceeding a predetermined amount to maintain said valve means in a closed position for safety purposes until overridden,
• means responsive to the electrical conductivity of liquid on the inlet side of said valve means to detect the presence of water therein, and
• electric circuit means interconnecting said conductivity-responsive means and said electrically-operated valve means and operable to energize said valve means to open the same on detection of the presence of water in the inlet thereto.

A safety valve apparatus for use in a system for a hydrocarbon storage tank having a floating roof, a water drain in said roof, a drain opening from said tank, and a flexible line connecting said roof drain to said tank drain for carrying off rain water collected on said floating roof and preventing leakage of hydrocarbon liquid and through said tank drain, said apparatus comprising;

• an electrically-operated, normally-closed valve means adapted to be connected in said tank drain,
• means responsive to the electrical conductivity of liquid on the inlet side of said valve means to detect the presence of water therein,
• electric circuit means interconnecting said conductivity-responsive means and said electrically-operated valve means and operable to energize and valve means to open the same on detection of the presence of water in the inlet thereto,
• a primary power supply for operating said valve means,
• a secondary power supply operative in responsive to the failure of said primary power supply for operating said valve means, and
• means adapted to be connected to an external power source for continuously charging said primary and secondary power supply.

A safety valve apparatus for use in a system for a hydrocarbon storage tank having a floating roof, a water drain in said roof, a drain opening from said tank, and a flexible line connecting said roof drain to said tank drain for carrying off rain water collected on said floating roof and preventing leakage of hydrocarbon liquid and through said tank drain, said apparatus comprising;

• an electrically-operated, normally-closed valve means adapted to be connected in said tank drain,
• means responsive to the electrical conductivity of liquid on the inlet side of said valve means to detect the presence of water therein, and
• electric circuit means interconnecting said conductivity-responsive means and said electrically-operated valve means and operable to energize said valve means to open the same on detection of the presence of water in the inlet thereto,
• a normally-open, motor-operated gate valve adapted to be positioned in said drain,
• an electric motor operatively connected to said valve and operable to open and close the same,
• a pair of sensors adapted to be positioned in the inlet to said valve to detect electric conductivity of liquid therein and permitting a flow of current when immersed in water,
• an electric relay adaptedto be connected to said motor and operable to energize said motor to move said valve to an open or a closed position,
• a plurality of NOR gates and a field effect transistor interconnected in circuit with said sensors and said relay and operable on current flow between said sensors in the presence of water to actuate said relay to energize said motor to open said valve and operable in the absence of current flow between said sensors to energize said motor to close said valve.

A safety valve apparatus for use in a system for a hydrocarbon storage tank having a floating roof, a water drain in said roof, a drain opening from said tank, and a flexible line connecting said roof drain to said tank drain for carrying off rain water collected on said floating roof and preventing leakage of hydrocarbon liquid and through said tank drain, said apparatus comprising;

• an electrically-operated, normally-closed valve means adapted to be connected in said tank drain,
• means responsive to the electrical conductivity of liquid on the inlet side of said valve means to detect the presence of water therein, and
• electric circuit means interconnecting said conductivity-responsive means and said electrically-operated valve means and operable to energize said valve means to open the same on detection of the presence of water in the inlet thereto,
• a normally-open, motor-operated gate valve adapted to be positioned in said drain,
• an electric motor operatively connected to said valve and operable to open and close the same,
• a pair of sensors adapted to be positioned in the inlet to said valve to detect electric conductivity of liquid therein and permitting a flow of current when immersed in water,
• an electric relay connected to said motor and operable to energize said motor to move said valve to an open or a closed position,
• a plurality of NOR gates, an OR gate, and a field effect transistor interconnected in circuit with said sensors and said relay and operable on current flow between said sensors in the presence of water to actuate said relay to energize said motor to open said valve and operable in the absence of current flow between said sensors to energize said motor to close said valve.