A double gas pressure seal 10 is provided for sealing between a stationary housing 14 and a rotary housing 26. The gas pressure seal includes a stationary ring 42 and a rotary ring 40 each having a radially inner sealing face and a radially outer sealing face. A biasing spring 56 biases one of the rings toward the other ring. An annular groove 68 is provided in one of the rings, with the groove being spaced between the radially inner sealing faces and radially outer sealing faces. A supply port 84 supplies pressurized gas to the annular groove at a pressure higher than the process fluid in the stationary housing. A plurality of radially inner and radially outer recesses 94, 96, 122, 124 are provided on the one of the rings, and corresponding feed channels 98, 100, 126, 128 fluidly interconnect the annular groove with a rotary leading portion of each respective recess. A small quantity of pressurized gas escapes between the inner sealing faces to atmosphere and between the outer sealing faces to the process fluid sealed in the stationary housing.