A downhole temporary pressure isolation tool configured to withstand very high gas pressures at high temperatures may be achieved by a variety of configurations, processes, and techniques. In particular implementations, a barrier valve having one or more frangible discs configured to resist fluid flow in a particular specified duration. In some implementations, the barrier valve may achieve a V0 rating. In one embodiment, for example, a barrier valve may prevent the passage of fluid (i.e., gas and/or liquid) at 15,000 psi and a temperature of 400 degrees F. for at least 15 minutes. If the barrier valve has two frangible ceramic discs, it may prevent the passage of fluid from two directions for at least 15 minutes.