Intelligent retrofit seismic wave detector and valve shutoff device

A method of closing a shutoff valve of a fluid supply line by a valve shutoff device comprising a coupling key for coupling with an actuator of the shutoff valve, the method comprising:

• by a processing unit of the valve shutoff device:
• receiving a first plurality of acceleration measurements made by an accelerometer of the valve shutoff device in three directions comprising a vertical direction;
• using the first plurality of measurements, determining an arrival of seismic primary waves (P-waves) when a ratio of vibrations' power in the vertical direction with respect to a sum of the vibrations' power in the three directions exceeds a first threshold;
• after determining the arrival of the P-waves, receiving a second plurality of acceleration measurements made by the accelerometer;
• using the second plurality of measurements, determining an arrival of seismic secondary waves (S-waves) when the sum of the vibrations' power in the three directions exceeds a second threshold;
• after determining the arrival of the S-waves, receiving a third plurality of acceleration measurements made by the accelerometer;
• using the third plurality of measurements, determining an arrival of seismic surface waves when the sum of the vibrations' power in the three directions exceeds a third threshold, the third threshold larger than the second threshold;
• and
• after determining the arrival of the surface waves, sending a signal to a motor of the valve shutoff device to rotate the coupling key and the actuator of the shutoff valve to close the shutoff valve,
• wherein the processing unit is one of a microprocessor, a controller, a microcontroller, a single processor, and a multi-core processor.

A valve shutoff device, comprising:

• a coupling key for coupling with an actuator of a shutoff valve on a fluid supply line;
• an accelerometer for making acceleration measurements in three directions comprising acceleration measurements in a vertical direction;
• a motor for rotating the coupling key and the actuator of the shutoff valve;
• a processing unit for:
• receiving a first plurality of acceleration measurements made by the accelerometer;
• using the first plurality of measurements, determining an arrival of a first set of seismic waves comprising primary waves (P-waves) when a ratio of vibrations' power in the vertical direction with respect to a sum of the vibrations' power in the three directions exceeds a first threshold;
• after determining the arrival of the P-waves, receiving a second plurality of acceleration measurements made by the accelerometer;
• using the second plurality of measurements, determining an arrival of second set of seismic waves when the sum of the vibrations' power in the three directions exceeds a second threshold;
• and
• after determining the arrival of the second set of seismic waves, sending a signal to the motor to rotate the coupling key and the actuator of the shutoff valve to close the shutoff valve,
• wherein the processing unit is one of a microprocessor, a controller, a microcontroller, a single processor, and a multi-core processor.