Reducing Valve for RO system, Water Pressure Regulator, Relief Reducing Valve Filter RO Water System, 3/8 Quick Connect

I bought this because my water pressure was too high going into the under sink RO system. Prior to adding this pressure regulator the water line going into the RO would hum loudly and even vibrate. Immediately after installing this regulator, the problem went away. The system now works perfectly. It took all of 2-3 minutes to cut the water in 3/8 inch tubing and install this inline regulator. Be sure to follow the arrow which indicates the water flow direction. Also be sure to firmly push the water tubing into the regulator until you feel that it is firmly and fully in.

Installation is fairly easy but instructions non existent. After letting the RO tank fill up when I turn on the RO faucet there is a loud hammering sound and the vibration felt if you put your hand on the valve. It goes away after about 15 seconds but doubt it is good for my RO system to go thru this vibration. UPDATE: If you install this unit in the water line coming from the tank where water actually flows in both directions, the arrow must point toward the faucet otherwise you will get water hammer when you open the faucet. Also this is not a relief valve, just a pressure regulator.