Abstract: In a combination including a communications conduit containing pressurized fluid and a smaller conduit sealingly connected therewith for testing the pressure of the fluid therewithin, an improvement characterized by a controlled flow check valve connected serially with the smaller conduit and sealingly with the communications conduit, the controlled flow check valve having a conventional poppet and seat means for allowing full flow in one direction for pressurizing and blocking reverse flow for preventing depressurizing; and a controlled flow bypass structure allowing a controlled reverse flow sufficient to permit testing of pressure but insufficient to bleed the pressurized fluid from the communication conduit in a short time. Also disclosed are the specific preferred structural embodiments that are economical and readily manufactured in contrast to elaborate apparatus enabling accomplishing a similar result in the prior art.