Fluid overfill protection and product identification system

A fluid transfer system for transferring fluid to and from a first tank, fluid transferred out of the first tank being transferred to a second tank via an output conduit and fluid being transferred into the first tank being received from a third tank via an input conduit, flow into and out of the first tank being controlled with a flow controller, the system comprising:

• a level sensor which detects fluid in the second tank and which outputs a first signal indicating whether the fluid level in the second tank is above a predetermined level, the first signal having a first time-varying characteristic which is indicative of a specific fluid for which the second tank is intended;
• an overfill detector which detects the first signal when the output conduit is arranged to allow fluid flow from the first tank to the second tank, and which causes the flow controller to inhibit fluid flow through the output conduit when the first signal indicates that the fluid level in the second tank is above said predetermined level;
• a signal generator which generates a second signal having a second time-varying characteristic which is indicative of a specific fluid contained within the third tank;
• an ID detector which detects the first signal when the output conduit is arranged to allow fluid flow from the first tank to the second tank, and which detects the second signal when the input conduit is arranged to allow fluid flow from the third tank to the first tank, the ID detector providing an output indicative of whether a detected signal has a time-varying characteristic which matches a stored representation of a reference time-varying characteristic indicative of a specific fluid type;
• and
• a disable device which receives the output from the ID detector and causes the flow controller to inhibit fluid flow into or out of the first tank if said output indicates that the time-varying characteristic of said detected signal does not match the reference time-varying characteristic.

A method of controlling fluid transfer from a first tank to a second tank through a transfer conduit using a flow controller to control the flow of fluid through the conduit, the method comprising:

• detecting fluid level in the second tank with a level sensor;
• outputting, from the level sensor, a first signal indicative of whether the fluid level in the second tank is below a predetermined level, the first signal having a first time-varying characteristic which is indicative of a specific fluid for which the second tank is intended;
• detecting the first signal with an overfill detector;
• generating, with the overfill detector, an overfill signal which causes the flow controller to inhibit fluid flow through the conduit when the first signal indicates that the fluid level in the second tank is above said predetermined level;
• detecting the first signal with an ID detector;
• comparing the first time-varying characteristic to a stored representation of a reference time-varying characteristic with the ID detector;
• and
• generating, with the ID detector, an ID signal which causes the flow controller to inhibit fluid flow through the conduit when the two characteristics are not sufficiently similar.