Low mains tap pressure

[H20]

Hi all

Recently got myself a 4040 RO unit, I have low mains tap pressure but I thought I'd hook it up anyway to see how little pure water is produced on standard pressure. (few trickles which I expected) 

The thing is that when  the waste water hose got caught and blocked (accidentally) it seemed to produce a reasonable amount of pure water with zero waste, 

Surely if the waste is blocked then the pressure inside the vessel builds up which in turn produces more pure water? Without a booster pump.

The pressured water can only escape through the membrane and out of the  pure water outlet 

Am I right in thinking this or will it damage the membrane? 

 

[spruce]

Hi all

Recently got myself a 4040 RO unit, I have low mains tap pressure but I thought I'd hook it up anyway to see how little pure water is produced on standard pressure. (few trickles which I expected) 

The thing is that when  the waste water hose got caught and blocked (accidentally) it seemed to produce a reasonable amount of pure water with zero waste, 

Surely if the waste is blocked then the pressure inside the vessel builds up which in turn produces more pure water? Without a booster pump. 

Am I right in thinking this or will it damage the membrane? 

Yes it will. If you block the waste off where do you think all those dissolved solids that the membrane has removed to produce pure have gone?

It needs the waste water to flush away these extra minerals. If they aren't flushed away your membrane will block up and will need to be replaced.

Your water going to waste is going to have a higher tds than your tap water.

At the least you need a 50/50 waste to pure ratio. If you haven't got good water pressure and/or flow then you need to identify why. If its because of a genuine supply issue from the water board, then you need a booster pump.

.

 

[H20]

In terms of a booster pump, I'm looking at either a 150psi @ 6.8 lpm or 100psi @ 12lpm 

Would you recommend a slightly higher psi with lower lpm or vise versa? 

 

[spruce]

In terms of a booster pump, I'm looking at either a 150psi @ 6.8 lpm or 100psi @ 12lpm 

Would you recommend a slightly higher psi with lower lpm or vise versa? 

I don't know which booster pumps you have found but 6.8lpm isn't enough to run a 4040. You need around 9 or 10 liters per minute.

The 12lpm unit is within spec but it sounds very much like they have 'tuned' it to satisfy water authority regulations that limit the amount of water a booster pump can draw directly from the mains. It would be interesting to see the spec or a link to it.

The one that does work is the unit sold by Gardiners for the PRF, 4021 and 4040. It has an electronic controller that will help if you have an auto fill switch off solenoid and float switch the activates to switch the water of to the tank when its full.

.

 

[Spartan]

The one that does work is the unit sold by Gardiners for the PRF, 4021 and 4040. 

.

Semi hijack thread....

4021 & 4040...

What's the difference between these 2 things?

I've done a search on the site but nothing.

 

[spruce]

Semi hijack thread....

4021 & 4040...

What's the difference between these 2 things?

I've done a search on the site but nothing.

4021 is half the size of a 4040. Same diamt but half the length, so pure production is half that of a 4040 under identical circumstances.

I reasoned right from the beginning that a 4021 doesn't cost half the price of a 4040. If I started with a 4021 and found it too small, I could easily add another membrane and housing so would have the equivalent of a 4040.

However, when the time came to replace the membranes, my bill would be more for 2 x 4021 membranes than it would for a single 4040 membrane.

So I went for a 4040.

At 50 psi my 4040 produces 2lpm of pure with an HF5 membrane. The 4021 would produce 1lpm.

If there is just one of you and you process water into an IBC tank, then a 4021 is good enough.

When considering what r/o to go for you need to ascertain the flow of water from the tap in LPM and your water pressure. Ours is 13lpm of water from the tap so more than sufficient to run a 4040. I have also fitted a float switch to my IBC tank which means that the water to the r/o automatically switches of when the IBC tank is full.

So when one of the lads drew water during the day I often didn't know as the IBC tank was full again when I got back in the evening.

.

 

[Spartan]

cheers Spruce,

Your answers are always so informative and detailed - much appreciated.

I'm going to bookmark all your responses as it will help me when I decide what RO etc to purchase.

Having your brains to pick is a real asset to the forum.

Cheers buddy.

 

[H20]

@spruce

Thanks for the info! Much Appreciated!

There's a few versions from the company 5/7/10/12 lpm's... Here's the link to the pump

 http://www.vyair.com/scripts/prodView.asp?idproduct=108

I've bought from this company before and its always been decent stuff... 

Let me know what you think 

Cheers spruce! 

 

[spruce]

@spruce

Thanks for the info! Much Appreciated!

There's a few versions from the company 5/7/10/12 lpm's... Here's the link to the pump

 http://www.vyair.com/scripts/prodView.asp?idproduct=108

I've bought from this company before and its always been decent stuff... 

Let me know what you think 

Cheers spruce! 

Sorry @H20. That's not what you want. Its a transfer pump. Vyair sell the same pump in lower 5lpm variants as a wfp pump.

If this worked then we would all be using them rather then the more expensive units that suppliers sell for this application.

Even they advise on the same page of the link that this can't be used as a booster pump.

IMPORTANT: This pump can also function as a water transfer, however it is too powerful to be used as a booster pump for your pole window cleaning system. This may cause damage to both your pump and pole-fed application.

The too powerful is rubbish; cause damage to the pump; yes, its just not designed for use in a continuous application. Under full boost that 4040 of yours will consume about 9 liters of water a minute. The 12lpm that the pump is rated at is full flow with no pressure. As the pressure builds up in the system the flow rate reduces. This is true of all pumps.

Our Shurflo pumps we use on the van are 5.2lpm pumps at 0 psi. As the pressure builds the flow rate drops off. At 100psi the pump delivers less than 1/2 the flow it did at 0psi.

Machine Mart sell a Clarke CBM240E pump

https://www.machinemart.co.uk/p/cbm240e-1in-multi-stage-230v-booster-pum/

and Gardiners sell a Wortex pump which is similar to what other suppliers also sell for that application.

http://gardinerpolesystems.co.uk/all-products/pure-water-systems/water-treatment/booster-pumps/switched-booster-pump-kit-240v-for-prf-ro-systems.html

There was a discussion about booster pumps on the other forum recently. Some posters advise that they have successfully used

https://www.machinemart.co.uk/p/051012200/

and

https://www.machinemart.co.uk/p/clarke-epc800-electronic-water-pump-control-un/

 when used in conjunction with a float control switch that cut water to the r/o when the holding tank is full.

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