Black Compression Fittings (.700 OD Tubing)

The colors of compression fittings often indicate the size compatibility of the fitting with specific types of poly tubing. Black is generally used for poly tubing with an outside diameter (OD) of 0.700 inches. Blue usually signifies a fit for poly tubing with an OD of 0.710 inches. This size may sometimes have a blue stripe on the tubing itself.

To remove a compression fitting, you’ll need to use a wrench to loosen the compression nut then unscrew it from the fitting. After the nut is removed, slide off the compression ring. If it's stuck or difficult to remove, feel free to cut it off, as compression rings can be replaced. Once the nut and ring are removed, the pipe should easily slide out of the fitting.