AutoShut off / Back flow

[cavediver]

Hi,
I have a quick question for you guys. I'm going to buy a automatic shut off valve for my R/O unit from AJ.

The Autoshut off valve page says "WE STRONGLY SUGGEST A BACKFLOW PREVENTOR WITH THIS PURCHASE"

The Backflow preventer page " In-Line Check Valve used to prevent back-flow.Needed when using an Automatic Shut-Off unit."

O.K....So I need to buy both peices, but can you explain to me the purpose of the check valve??

I think I understand the functionality of the shut off. Basically I'm picturing a membrane that swells from tank pressure on the product side and pinches off the supply line side. Which stops the flow of fresh water into the prefilters. But I don't understand how/or why the check-valve is there??

Thanks for your help once again,!

John :help:

[aquafx]

OK, let me try to put this in writing;

The automatic shut off works when the "float valve" sends a back pressure across the tubing to the automatic shut off. If a very little bit of water backflows through the membrane it will loss just enough pressure drop to let the diaphram open, then it will build pressure again and, well it starts to cycle and make alot of noise. Lots of vibration.

This does not always happen, only about 20% of this time. But as a company, it makes better sense to send customers the proper equipment and stop any potenial problems.

I hope this helps!

Marianne