A rotary union includes a rotating seal carrier having a rotating seal member connected thereon, and a non-rotating seal carrier having a non-rotating seal member connected thereon. A piston portion of the non-rotating seal carrier has a flow restrictor ring disposed thereon, and both are slidably and sealably disposed within a piston bore formed in a housing. A gap is formed between an outer diameter of the flow restrictor ring and an inner diameter of the piston bore. The enlarged diameter of the piston portion provides a net pneumatic or hydraulic surface that can be acted upon by a fluid at a positive or negative atmospheric pressure present within the piston bore of the housing.