A probe comprising of a probe body, a probe post positioned in the probe body and having a forward end with a forwardly tapering front face and a rearwardly tapering probe post seat. A probe seal is provided within the probe body having a forward end with a rearwardly tapering probe seal opening forward end of the probe seal has a seal face. The forward end is movable rearwardly from a closed position sealingly mating against the probe post seat to close the probe seal opening to an open position in which the probe seal face is spaced from the probe post seat to allow fluid to pass through the probe seal opening and hence through the probe. A first resilient means for urging the forward end of the probe seal into the closed position.