RO Production Information Thread

[J and S]

Cheers for that Spruce increases the pressure but reduces the flow got that although I have just put a smaller diameter pipe as we type and the flow of pure at the end has increased slightly.

Next question then....how will putting a pump between tap and ro increase the pressure with the same flow...surely it will just overdraw on the supply......excuse what may seem like simple questions.

 

[spruce]

Cheers for that Spruce increases the pressure but reduces the flow got that although I have just put a smaller diameter pipe as we type and the flow of pure at the end has increased slightly.

Next question then....how will putting a pump between tap and ro increase the pressure with the same flow...surely it will just overdraw on the supply......excuse what may seem like simple questions.

That's what happens. This is why the water authority regulations regarding booster pumps limit the amount of water your booster pump can draw to 12 lpm. So if a booster pump is put ahead of a 4040 r/o you won't have a problem if the r/o is set up properly. But you mustn't flush the r/o with the booster pump in action as the user could well exceed those 12lpm.

12lpm seems to be the figure that has been settled on that won't cause others (neighbours) in the supply chain any inconvenience. The user has got to consider that if his tap is only delivering 5lpm then adding a booster pump to a 4040 will increase the draw of water to around 9-10lpm. He is obviously going to starve all other taps and outlets of water whilst the booster pump is working.

The problem comes when the water board turns off someones water supply for none payment. By law the stop valve in the street can't be completely closed. They have to allow a trickle of water to the property for health reasons. If a booster pump were to be fitted to that supply then there is the possibility that the suction caused could collapse the water pipes.

With regard to a smaller pipe, the pressure or driving force behind the water will force the water through the pipe faster. But there comes a limit. As long as the flow is rushing through the pipe smoothly everything is fine. However, it changes at a certain rate when the water in the pipe becomes turbulent. Then it starts to change and doubling the water pressure might not improve the flow rate by much more. There is no set rule as to when the water will start to become turbulent, but if its being forced around coiled hose on a hose reel, it will become turbulent sooner than if it were laid out in a straight line.

.

Take a look at this @J and S

http://www.flourmilling.co.uk/water.html

I realise its steel pipe but I see the flow rate difference between 6mm and 8mm bore steel pipe is considerable. At 4 bar the flow through 6mm pipe is 0.022 liters per second. The 8mm pipe its  0.056 liters per sec at the same pressure. So a 6mm tube will only allow fractionally less than 1/2 the volume of water at 4 bar. Our hose coiled up around a hose reel will probably reduce those figures a bit more.

Hot water will have a higher (or is it lower) viscosity (less dense) so will flow better through a smaller diamt hose. So most hot water users happily use microbore hose.


http://www.frca.co.uk/Documents/100308 Physics of flowLR.pdf

Interesting read these 7 pages.

Look at the difference between Laminar flow and Turbulent flow. Once fluid in a tube reaches a certain speed it become turbulent. Once it becomes turbulent it requires 4 times the amount of pressure to double the flow rate. Fluid through hose coiled on hose reels won't be laminar in flow but turbulent.

.

 

[adamangler]

At the momemt 200 in 

13 out

Mines just a cheap (£150) 100 gpd r.o that I upgraded to 150gpd when o last change the membrane.

No idea what pressure ia

No useful info on the rest of it as it's never been an issue

I must admit I never flush mine or owt, change the filters about 6 monthly and the membrane yearly

 

[J and S]

Flush it through every time I use till it reads 2 or 3 before entering di......di resin lasts forever here with a ro.

Thanks for that Spruce very informative.

 

[Redditch windy]

ive got about 20ppm out after changing membranes on my collins system 450gpd and producing circa 25l p hour without a booster pump (circa 250ppm to start with) dont know if thats good or bad

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[spruce]

ive got about 20ppm out after changing membranes on my collins system 450gpd and producing circa 25l p hour without a booster pump (circa 250ppm to start with) dont know if thats good or bad

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Before these cheap membranes became available from Asia, the old rule of thumb was to consider replacing membranes when their efficiency dropped to around 94%. Even with lowish water pressure our Filmtec and Axeon membranes have consistently worked at around 98%.

As I posted before, HiD quoted their rejection rate of between 90 and 99%.  At the figures quoted your membrane efficiency or rejection rate is 92%. So according to HiD those membranes are performing to spec - no further action necessary.

At the risk of upsetting some posters on here, you get what you pay for. Collins sells membranes for many different applications and for most of those applications such as drinking water, those figures are totally acceptable. But with window cleaning we need the purest water we can get, and, I'm sorry, those membranes just aren't good enough IMHO. (I have no issue with Collins or any of the staff who work there.)

Lets use your figures. We ran a 450GPD r/o for 6 years with quality Filmtec membranes. (Our current 4040 r/o has an Axeon membrane which will be 5 years old next month.) Our tap water tds was 254 for a number of years and our water pressure was 40psi. Those membranes consistently produced a rejection of 4ppm which we polished off with resin. Lets assume that the 2 of us drawing water would use 10000 liters a month. (We use slightly more than that now as we have a water meter on the r/o.)

According to the Gardiner Resin calculator (which I've found to be reasonably accurate over the years) I would use approx £6 of resin to polish that off a month.

If I was to use your r/o then my resin costs would be £29 a month.

Now Collins are selling 3 x 150gpd membranes for £95.50.

If I go the Daqua I can buy 3 x 150gpd Axeon membranes as £106.20.

For me with my half a brain I don't need convincing which membranes I should buy.

Annually, using Hid membranes, resin would cost me £348 and £2088 over the 6 years they lasted for.(Bearing in mind that even at that rejection rate HiD would be happy with those results as the membranes would be performing within spec.)

Using the Filmtec membranes our resin costs would be £72 and £432 over the 6 year period.

So I saved £1656 in resin costs using membranes that cost £11.00 more.

As a single operator your water usage will be less but you can use these figures as a comparison. So if you were using 4000 liters of pure a month then your resin costs would be around £11.60 per month

The first thing I would do is individually check the tds of the pure of each membrane individually to see if you haven't a 'rogue' membrane or one that hasn't been connected up correctly.

If they are all producing the same result, then I see the only recourse to chuck them out and buy decent ones.

Sorry for being blunt.

.

 

[Redditch windy]

my new membranes are all 150gpd axeon membranes;not the cheaper ones

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[spruce]

my new membranes are all 150gpd axeon membranes;not the cheaper ones

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Sorry, I've got your post and another mixed up. :1f634:

I would check the output of each membrane and ensure that each is connected up correctly.

Maybe @doug atkinsoncan through in a few pointers.

 

[Redditch windy]

just checked and its dropped to 14ppm now

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[doug atkinson]

When we test our R/O Systems we flush for a good couple of hours to get rid of the chemicals. We then close the flush valve and often enough it is sitting at 96/7% rejection rate so there is still room for improvement after more flushing.

Manufacturer advises to flush for 24 hrs. But this would be a waste of water so in time the membrane will bed down after a couple of days.

If you still have issues take a reading from each membrane and you sometimes one is a lot higher. Reseat this back in and hopefully this is the issue.

 

[Tuffers]

Update on my poorly running RO. I was getting 20psi from the tap and a TDS of 044PPM from the old membrane. I bought a new membrane and that brought the TDS down to 019/020PPM but the psi was still 20. I bought a booster pump from Gardiners and rigged it up earlier. I'm getting 80psi and a TDS of 009PPM from the RO. I made 300 litres of pure in about an hour or so.

Happy bunny here  :1f44d:

 

[RyeCleanLiam]

Update on my poorly running RO. I was getting 20psi from the tap and a TDS of 044PPM from the old membrane. I bought a new membrane and that brought the TDS down to 019/020PPM but the psi was still 20. I bought a booster pump from Gardiners and rigged it up earlier. I'm getting 80psi and a TDS of 009PPM from the RO. I made 300 litres of pure in about an hour or so.
 
Happy bunny here /emoticons/1f44d.png

Glad you're sorted Tuffers. How much did the booster cost if you don't mind me asking?


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[Tuffers]

Glad you're sorted Tuffers. How much did the booster cost if you don't mind me asking?


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I bought this one http://gardinerpolesystems.co.uk/all-products/pure-water-systems/water-treatment/booster-pumps/switched-booster-pump-kit-240v-for-prf-ro-systems.html. I opted for the fully wired up one as I couldn't be arsed spending half a day faffing about wiring it up. I emailed @Alex Gardiner out of business hours and he ran through what fittings and connectors I'd need to rig it up to my system. This man goes further than the call of duty. Thanks for the Mr G.