20 to 16 mm Lock-Nut Reducer for Drip Irrigation Tubing

Connect a 20 mm irrigation supply tube to a 16 mm lateral with one straight reducing fitting. The two ends are deliberately different sizes: the larger lock-nut connection takes the 20 mm tube and the smaller connection takes the 16 mm tube. Use it where the pipe route continues in line while stepping down to a smaller diameter.

Match both sides before cutting

Confirm which line is 20 mm and which is 16 mm at the installation point. The nominal sizes refer to two separate connection ends, not an adjustable fitting. Check the actual tube outside diameters, wall construction and fit with the inserts before buying. If the branch needs to leave at an angle, choose a tee or elbow instead of this straight reducer.

Plan an accessible transition

Leave enough straight tube on each side to seat the ends fully and tighten the locking nuts. Support the wider supply line and the narrower lateral so a change in diameter does not become a point where the tubing is pulled or sharply bent. The reducer provides a mechanical size transition; it does not regulate pressure or set flow for the downstream emitters.

Fit and inspect

Shut off the supply and relieve trapped pressure. Cut both tube ends squarely, keep dirt out of the waterway, seat each end over its matching insert and tighten the corresponding nut by hand. Restore water slowly, inspect both joints under normal operation and correct any leak only after pressure has been released.

Sold as one reducing coupling. Irrigation tubing and other installation parts are separate.