Systems, devices, and methods are described herein for extinguishing fires in a flammable liquid test pan. In an example, the system can include a substantially impermeable lid configured to mate with a top surface of the test pan. When the lid is mated with the test pan, the lid deprives an enclosed volume of the test pan of ambient combustible gas. The lid can be made of one or more materials including metals, ceramics, aramid fibers, and other gas-impermeable and fire resistant materials. The system can include a vehicle configured to carry the lid from a first location that is distal to the test pan to a second location that is adjacent to the test pan. In an example, the vehicle includes a lid transfer device that facilitates transferring the lid from the vehicle to the top surface of the test pan.