The air gap has 2 different size barbs, a small barb which is the brine inlet and a large barb which is the brine outlet. Attach a 1/4" outside diameter (.040 wall) tube (not supplied) to the brine inlet. Attach a 3/8" outside diameter (.060) wall tube (not supplied) to the brine outlet (NOTE: It is important that enough tubing is installed on the brine inlet and brine outlet of the air gap so that installation of RO unit can be successfully completed. Excess tubing can be trimmed to the proper length after faucet is mounted. Tubing is not supplied with faucet. Installation must be in accordance with all applicable local plumbing codes). 

Locate mounting hardware (refer to figures on opposite side). This will consist of six items; a black rubber gasket, mounting washer, spacer (use if needed), flat washer, lock washer and a mounting nut. With black rubber gasket in hand, feed tubing from faucet through rubber gasket. Align rubber gasket with bottom of base. Next, add remaining 5 parts to the threaded copper tube loosely (do not tighten). Parts are to be assembled in the same order listed above, except for mounting washer, set this aside (do not discard). Next, feed all tubes and mounting hardware into the mounting hole in sink using care, as there may be sharp edges if a new hole has been made. With faucet base and gasket seated over mounting hole, take the mounting washer and slide it between mounting surface and spacer (if spacer is not being used, slide between flat washer and mounting surface) keeping in line with threaded copper tube. Tighten mounting nut so that faucet barely moves against mounting surface, adjust faucet to desired orientation on sink. Tighten mounting nut, do not over tighten. With faucet in place and tight, plumbing connections can be completed. 

To connect cold water supply line when not using an air gap (without RO system), locate 1/4" diameter blue cold water inlet tubing (supply inlet) that passes through the threaded copper tube. Connect this tube to any cold water supply line with the use of a saddle valve (not provided) or any other approved method (consult local plumbing code) (Note: Removal of the 1/4 diameter blue cold water inlet tube (supply inlet) from threaded copper tube will void warranty). 

Non Air Gap: 

Non air gap faucets have no Air-Gap function built into them. These faucets have a single line from the tank to the faucet.

Air Gap:

An air gap faucet which contains an empty space built in the base of the faucet. Air-gap faucets have three lines attached to them. (1) line from the tank to the faucet (2) a water line from the brine water side of your RO. (3) a drain line for the brine water that attaches to the drain saddle. Please check your local code to determine if an air-gap is required.