US Patent 9284825 Gas-lift safety valve actuated by a sensor

A valve actuator, valve, and method of actuation of a valve are disclosed. The valve actuator includes a shape memory alloy element attachable to a valve body, capable of use with a valve to cause movement of the valve between first and second positions. The valve actuator also includes a sensor located within a well and capable of detecting the presence of a fluid based on a fluid property of the fluid. The valve actuator includes a power supply electrically connected to the sensor and the shape memory alloy element, capable of applying an electric current to the shape memory alloy element in response to the sensor detecting the presence of the fluid. The electric current causes a temperature of the shape memory alloy element to increase beyond a threshold temperature at which the shape memory alloy element actuates.