a coolant union includes a seal assembly having a first seal member and a non - rotating second seal member . at least one of the annular sealing surfaces presented by the rotating seal member and the non - rotating seal member is chamfered such that the chamfered sealing surface presents a sealing surface width less than the width of the dimension of the other sealing surface . the fluid coolant union further includes a u - shaped annular secondary seal member having a chamfered portion structurally arranged to receive a triangular back - up ring which stores sufficient relative displacement of the floating seal assembly to create a separation between the first rotating seal and the second non - rotating seal members during the unpressurized condition .