Help with RO machine

[APW]

I replaced everything on this old Dilling Harris RO machine and it is working but I have a few questions. The incoming TDS it's 397 and the RO water is 3.

What is the timer for? I'm assuming to flush the membranes but how does it do it. It looks to me it just energizes a valve that dumps to the drain. Can someone explain how and why it works.

On the product water the flow is around 2.5 and the reject is 3 gallons, the pressure is 190. Is this good or where should it be set. Thanks for your help.

https://imgur.com/a/ozv1sRo

 

[MEP001]

The timer looks more like a household timer than one that's usually used as a flush timer. If it is a flush timer, it should be set for as short a time as possible or you'll be wasting a lot of water. I've seen a timer like that used on a RO system to keep it from running while the softener is regenerating at 2 am so the RO won't be getting hard water.

Your settings are okay, depending on if it recirculates a portion of the reject. Best efficiency is 1:1 product/reject, but you need to dump at least 2 parts to 1 product if it doesn't recirculate anything.