PSI = How Man GPH

[JD'sReef]

So some of you may know that I am some slight hang ups with my 46 bow and I was woundering if anyone knew how man psi is = to 60gph. My top off system is good for 60 gpd but my RODI unit puts out 100gpd. A member sugested http://dripirrigation.com/index.php?cPath=31_95 but I need to know which one. I was thinking the 30 psi but not sure. Any ideas or any sugestions as to what to do?

Thanks
J.

 

[Anonymous]

The reason for me to suggest the use of a pressure regulator is because you told me the pressure output of your RO/DI (independent of GPD rating, BTW) is too high that the top off can't not shut off.... it drips constantly.

Call the maker of the topoff valve and ask them what is the PSI rating of the device, e.g., it is rated for 20 PSI max. etc... I am sure SpectraPure will be able to help you, and maybe able to give you a better pressure regulator, but again, give them a call.

There is no relationship between PSI (pressure) and GPD/GPH (production output in volume). You can have 100 gallon per day at 0.01 PSI, or 1 gallon per day at 2000 PSI. The reason you need to pick a pressure regulator for the output of your RO/DO is not to affect the GPD (it is determine by the amount of evaporation of your tank), but only to decrease the pressure on the output so that the topoff can function properly.

Recommandation:
1, call manufacturer and ask for the topoff spec.
2, see if you want to install a bladder tank so that the pressure regulator does not cause adverse issue with the RO/DI (RO hate back pressure).
or
3, get a better topoff that can work with pressure of 60PSI or above

 

[JD'sReef]

Alright,
Thanks again, I guess I need to do some research.
J.

 

[AnnArborBuck]

The key parameter for the performance of a RO unit is the entering pressure and the temp. Here is a link to see how pressure affects the rate on RO units http://www.gewater.com/library/tp/808_Fundamentals_of.jsp.

If you need to boost the performance of you RO unit you can get a pressure pump depending on the pressure in your area. You could also add an inline heater before the RO unit to get the temp up to normal operating temperature (density of water if a function of T, that is why the temp is important). Some people suggest restricting the reject water as this will increase the pressure on the membrane, thus increasing your processing rate. If you do this make sure you backflush your membrane to remove scale since this will buildup more and eventually render your RO membrane too slow or complete useless. Actually, you should backflush your membrane even if you don't restrict the reject water as this is a good practice.[/url]

 

[Anonymous]

I love Ann Arbor. Lovly college town.

The main issue here is high pressure on the RO output that make the top off valve not functioning well.

Anyway, since you mentioned a few things, I will offer my two cents.

1, pressure pump is only recommanded if the pressure is very low. The cost of the pump (~$100) and the amount of electricity it takes to run it make it not very economical way to booster output in most cases.

2, inline heater is another over-recommanded item. Heating gallons and gallons of water and drain 75% of the heated water away is a waste of electricity. Unless a heat exchanger is used to recover the heat in the brine water (waste water), it is not a good idea either

3, Over-restiction is another "trick" that mentioned once a while. Just like most tricks, there is a price to pay. In this case, a higher TDS usually will result in the output, in addition to the buildup you mentioned in your post. Over-restiction defeat the advantage of filter.

As always, look at the consequence of the suggestions, and make your decision on it. There is no free lunch.

 

[AnnArborBuck]

I guess I mis understood the question because I thought he RO/DI was not producing enough water.

As for your comments to my comments, I agree on most of it. Using an inline heater is not the best option, but the rate an RO operates is tied in fairly heavily with temp.

And if you restrict your waste water you should actually get a lower TDS over time due to the scale build up. As the scale builds up it creates smaller and smaller opening which increase the rejection rate. It also decreases your flow rate to the point where you will get no flow. That is why I said you have to backflush the membrane to remove the scale.

 

[Anonymous]

>...And if you restrict your waste water you should actually get a lower TDS over time due to the scale build up. As the scale builds up it creates smaller and smaller opening which increase the rejection rate. It also decreases your flow rate to the point where you will get no flow. That is why I said you have to backflush the membrane to remove the scale. ...

It sounds logical, but I am not convinced until someone actual experiment on it. Sometimes our intuition can be very wrong.

 

[JD'sReef]

Thanks for the replys all.
I actually took the easy way out and get a pressure regulator for airwaterice (something like that) and it should work just fine. I think it is just time for me to get home and start playing.
Happy holidays
J.

 

[Anonymous]

One idea I saw a while back for the whole "warmer water does better" bit is if your RO unit is near your tank (sump specifically) is to get a couple hundred feet of vinyl tubing, toss it all in the sump, then the incoming water has a chance to warm up before hitting the RO unit. Sure your tank heaters will work more (effectively becoming a chiller) but it might work out in the long run *shrug*

 

[Anonymous]

Have fun with the regulator, JD.

Alright, sounds like everybody is aware of the temperature vs output of RO. But like many things else, there is no free lunch. The higher the temperature, the more TDS going to creep thru. So you may get more water out of your RO, but there is more junk per volume too. Just something to keep in mind.