Automatic Shutoff Devices
An automatic shutoff device installed in an underground storage tank (UST) fill pipe will slow down and then stop the flow of product to the tank when the product has reached a certain level in the tank. Federal regulations require that shutoff occur when the tank is 95 percent full or before any fittings located on top of the tank are exposed to product. This device has one or two valves that are operated by a float mechanism. The illustration on the left below shows one type of automatic shutoff device. Note that the float is down and the fill valve is open. The illustration on the right below shows the same shutoff device with the float up and the fill valve closed.
Some automatic shutoff devices work in two stages. The first stage drastically reduces the flow of product to alert the driver that the UST is nearly full. The driver can then close the delivery valve and still have room in the UST for the product left in the delivery hose. If the driver does not pay attention and the liquid level rises higher, the valve closes completely and no more liquid can be delivered into the UST, leaving the driver with a delivery hose full of product.
Return to the Preventing Underground Storage Tank Releases page.