Description Compression outlets are used for water and compressed air lines, where slight leakage isn’t going to cause too much of a problem. Flared outlets are used for gas and high-pressure lines, where even a little leakage can cause major problems if left unattended. Although compression fittings are generally considered more reliable than threaded fittings, there are some potential problems. In general, compression fittings are not as resistant to vibration as soldered or welded fittings. Repeated bending may cause the ferrule to lose its grip on the tube.
