Gate valve- flushing?

Hi all 

On my current mobile system , the Gate valve if turned off fully still allows some waste water through / along with the pure water going to the tank, how is this the case with the valve shut?

When flushing the tank I turn the valve fully so that no pure is going into the tank and it’s all going through waste.

I’m currently setting up a static RO system and struggling to understand how to set up the ‘flushing’ process?

thanks in advance

SG cleaning solutions 

On which port is the valve located?

When not producing water the inlet port should be off.

When flushing the main inlet and waste outlet should be completely open. It'll still allow a tiny amount of pure to trickle through the pure outlet when flushing, depending on the water pressure. 

And of course when producing water, the waste outlet should be constricted correctly to allow pressure to build up in the membrane and produce pure at your appropriate ratio. 

Hi @Nudel

thanks for the reply!

i presume you mean the waste pipe out of the van that the valve on.

Sorry i’m a complete novice when it comes to this. When setting up my new static system how and what exactly do I need to set this flushing system up ? 

Also what is the desirable waste -pure ratio

If you have a PureFreedom system @sgcleaning then they drill a small hole through the paddle of the gate valve to let some water through even although the gate valve is fully closed. This ensures that a windie doesn't stop water going to waste when accidently closing the gate valve altogether and damaging an expensive membrane.

I don't know what size hole PF drill but I did the same thing when I set up my 4040 6 years ago. If I remember correctly the hole I drilled was 1.5mm and I still have to open the gate valve a little to balance the ratio of waste to pure when producing water.

Depending on the tds of your incoming water you could try a ratio of 60% waste to 40% pure to begin with. But it could be that the hole size PF drill will be for a higher waste to pure ratio. In our case having a 3 waste to 1 pure ratio (3 liters of waste to 1 liter of pure) is a waste of water. If the ratio is too high then I would replace the gate valve with a new one from any plumbing outlet. It won't have a hole drilled through the paddle but you must remember never to fully close the gate valve - ever. (The reason why I drilled a hole through the paddle of my gate valve was that 2 others also took water from our system and I was concerned that one of them might just play around with it when I wasn't there.)

What you are aiming for is the best ratio of waste to pure as this is achieved when the pure is at its lowest tds before di. To help me tune my gate valve I have fitted an inline tds meter with 2 sensors, the first is after the r/o but before the di vessel and the 2nd is after the di but before my IBC tank. I can open or close the gate vave fractionally to get the best tds reading from the membrane.

I dont get what people mean when they say the inlet port should be on or off.It cant really be shut on or off, not like the waste valve.

Also, would be interesting to know what different peoples set ups have as their waste/pure ratio. and their tap tds. reason I say is, Ive had a 4021 and got nearly 50/50, from tap 530 to 12 before the di. but now i have another one, still get 12 before the di, but ratio 3 waste to 1 pure. just odd how so different.

well, looking at my figures it was 60/40 to start but has gone 3 waste to 1 pure after about 6 months of not very heavy use. has anyone else had this and is it a pointer to anything? cant make it out to be honest.

ks789 said:

I dont get what people mean when they say the inlet port should be on or off.It cant really be shut on or off, not like the waste valve.

Also, would be interesting to know what different peoples set ups have as their waste/pure ratio. and their tap tds. reason I say is, Ive had a 4021 and got nearly 50/50, from tap 530 to 12 before the di. but now i have another one, still get 12 before the di, but ratio 3 waste to 1 pure. just odd how so different.

well, looking at my figures it was 60/40 to start but has gone 3 waste to 1 pure after about 6 months of not very heavy use. has anyone else had this and is it a pointer to anything? cant make it out to be honest.

Click to expand...

 I don't understand what @Nudel was referring to either.

My setup is a 4040 with 2 x 20" prefilters in a cabinet secured to the garage wall. The inlet comes from a pipe which supplies the downstairs bathroom and toilet. It goes into the cabinet at the bottom, through a 90 degree elbow and a ball valve. Next is a solenoid valve which is activated and deactived by a float valve in the IBC tank. A reinforced plastic hose then feed a couple of prefilters joined together with a barrel nipple. I have a pressure gauge on the inlet to the first prefilter which is a sediment filter. The second filter is a carbon block filter. There is a pressure gauge on the second prefilters exit and that goes into a water count down meter. (This meter is so I know when to change the prefilters, mainly the carbon block. Our water is sometimes is heavy laden with sediment. The sediment filter has been known to need replacing a couple of times before the carbon blocks service life is complete. When the gauges read a 10 psi difference I change the sediment filter. If the carbon block is just about due a change then I do them at the same time.)

That pipe then goes to the inlet of the 4040 housing. The 4040 is vertical. Its a champ housing so the pure outlet is at the top and the waste port is on the side. My gate valve is screwed into the waste which runs to the outside drain. Pure goes to the di vessel. Before the pure gets to the di vessel there is a sensor to tell me the quality of the pure the r/o is producing. Then the pipe exits the di vessel where there is another sensor to tell me the quality of the water after its gone through the resin beads to be polished off. The pure then leaves the cabinet, makes it way up to the roof rafters of the garage and then down to the IBC tank on the other side of the garage.

We have an external transfer pump which we use to fill the van/s with water.

ATM my pure to waste ratio is about 50/50 waste to pure. I've had best results with a 55/45 ratio during this summer when the water has been warmer. I've just replaced the prefilters and I've tweaked the ratio back to where it usually is.

Now if I throttle the waste back a liitle more to say 40 waste to 60 pure then the tds of my waste goes up by 1 point. That 1 point is 50% increase in tds going into the resin.

If I go the other way I will get the same tds at 60 waste to 40 pure  as 50/50 but I will use more water. If I go to 70 waste and 30 pure then the quality of my pure also suffers. So I will not only use more water, but I will also use more resin. At this ratio of 70/30 the pressure gauges drop so the reason for the pure tds increase is because there is less pressure on the membrane and its not working as efficiently.

Our tap water tds fluctuates between 79ppm (rarely) and 150ppm depending on which dam the water is being drawn from. Our usual tds is around 100ppm. My pure tds from the r/o is usually 2 or 3 depending on the water quality that day. A 6 liter di vessel lasts me about a year. (In fact, I lasted changed the resin in September 2017 and it was still reading 0 last Friday when I filled the van.

Our water pressure is around 50psi although it was 48psi on Friday. As the prefilters were new both gauges were reading the same pressure.

I'm using a Axeon HF5 membrane which was fitted in September 2012. and still performing at 98% efficiency. I do not have a booster pump. At 50/50 I get 2 liters of pure water per minute and 2 liters of waste over the same period. After I've taken about 300 liters from the IBC tank the float switch in the tank triggers the solenoid valve and that will remain open until the tank is full. If the wife wants to use a sprinkler on the lawn then I leave the r/o switched off until the evening.

Inside the cabinet I also have a 140 watt tube heater which is wired into a Frost thermostat. The thermostat kicks on at about 5 degrees and off again at about 8 degrees. This ensures my r/o isn't damaged with frost in the winter, even although its in the garage. I regularily test the tube heater to make sure its working during the winter. I've never had a issue with it in the past 6 years. Its the second tube heater. The first was a 40 watt and that wasn't big enough to keep the cabinet at the temperature I needed it to be.

The waste goes into the back drain from the bathroom. I also have an over flow pipe on the side of the IBC tank at the top  with a hose attached which goes out of the garage door to the drain off the garage roof. If something goes wrong its to save the garage being flooded out. In 10 years it saved the day once. I removed the float switch in the tank and didn't fit it back together properly - not an equipment failure but my fault.

These photos were taken after I completed the cabinet and doesn't show the water usage counter as it wasn't fitted then.

Thats a sound explanation, good set up too. I guess everyones situation is different with tap tds and pressure. With my 40 21 my best pressure to get the lowest tds is about 50. If I  close the valve a bit more to increase pressure my tds goes up a bit rather than  going down. the valve does seem like its almost fully closed but otherwise theres no pressure or not much. Its good to get 12 tds before di from tap of 530, but I do wonder on the waste /pure ratio. Its not bad with my usage I can put up with the water bill, but would be reassuring to know others have the same. Axeon from daqua so good and efficient. I might put a topic up 'whats you waste/pure ratio?' 

Cheers for the info spruce, informative as ever. In fact, I reckon there are enough windies out there now where a book could be a decent venture.

@spruceis back  :delusional:

spruce said:

 I don't understand what @Nudel was referring to either.

Click to expand...

I just meant the tap/source where you input the water you want to purify into your system.

Nudel said:

I just meant the tap/source where you input the water you want to purify into your system.

Click to expand...

Ok. I understand now?