flow sensor

[tuckermtn]

the second of what is likely going to be many RO questions as I'm the RO newbie-

the automatic shut-off (for lack of incoming sap) does not work on the memtek I just got. I would like to get someway of shutting off the RO with some type of inline flow sensor that when there was no flow, the sensor would send a message to the RO (or to a switch that would be tripped) and shut it off. It looks like the incoming sap was going through a 1" braided poly pipe.

does anyone have a sense on how to hook something like that up? Probably should call Powerdub...

[Homestead Maple]

Could be just a pressure sensitive switch, that unless it is satisfied it will interrupt the power to the pump.

[brookledge]

Eric
If you are feeding the ro with sap that is being pumped you could use a low pressure switch to shut off the ro. as soon as the pump runs out of sap the pressure will drop.
Or I would think that somewhere on the ro a pressure switch could be used to shut off the electricity.
I saw you go by me today in Whately. I was cutting trees with a tree company. I noticed your license plate but not in time to stop you to say hi
Keith

[802maple]

I am not familar with the exact system your RO has but it should have a automatic switch already on it. I would do some research as to where it is and find out what is wrong with it. If it is faulty, just get another one and replace it. As said above it is a low pressure switch just after your feed pump.

[Haynes Forest Products]

Tuckermtn You can get paddle switches that detect flow and will shut down equipment when it fails to activate. They are a little paddle that is in the liquid stream connected to a micro switch that activates a relay. The problem is they dont handle line voltage for pumps. The other dynamic is if a pump needs a pressure switch that is under pressure to run the pump and you cant run the pump until you have pressure you need a bypass switch to get the pump up to pressure for the system to run:o I would think a switch that was BEFORE the pump that detects flow would shut down the pump untill you reset it.

[danno]

This is probably too basic, but would probably work.

http://www.grainger.com/Grainger/wwg/productIndex.shtml?operator=prodIndexRefinementSea rch&originalValue=float+switch&L1=Pump+Switches%2C

I have one in my gravity tank above my evaporator and I love it. It automatically kicks my pump on when my sap gets low in the gravity tank. You would need the opposite, which would kick your RO pump off when the sap got too low. I saw a couple rated to work off 220.

[802maple]

Are you saying that the switch doesn't work or there isn't one? I haven't seen one in a longtime that did not have one installed already. If it simply isn't working it is much easier to just replace the one that isn't working instead of reinventing the wheel and putting a different setup in.

I have to believe that there is one, as these things have been made for maple since back in the 70's and it was just the very first ones that weren't automated

[tuckermtn]

I need to do some sleuthing and getting to know the machine, but it is my understanding that the one that is on there does not work- something about a circuit board not working- and I figured it was easier to bypass it then try and get a new circuit board or controller...

so yes it was automated

this is a vintage 1982 machine- the lettering and insulation on the front pannel caused Parker to dub it "sputnik" -

[Jim Brown]

tuckermtn; A pressure switch should not be hard to hook up to the feed pump,that is were mine is hooked. When the pressure drops due to the lack of sap flow(tank is empty) the system will shut down-feed pump-recirt pump-and high pressure pump
Just a thought
Jim

[802maple]

It should be a relatively easy fix as they were pretty basic at that time. It will have some kind of sensor to read the pressure, which will be right after the feed pump which will go to a controller, You might not be able to find that exact one but you will be able to find an acceptable replacement. I would highly doubt that it is the controller, it does happen but very rare. What I would bet on is the sensor as I have replaced alot of them. If your RO has self contained filters, the sensors are most generally located just after them. Good luck

[Haynes Forest Products]

One of the problems is without pressure to the switch it wont send a signal to the relay to start the pump. Some systems will start and then stop if it doesnt get a pressure signal in a very short time. That is why some systems will start then stop before pressure is built up. I would restore the original equipment so all works as planned. Even 30 seconds without liquid will trash some seals so dont jerry rig it.

[802maple]

Yes as Haynes says as some seals will not last long, and I do know they are not cheap. Some mechanical seals in these pumps cost upwards of $300.00

[Brent]

The start button should be a momentary contact button. That is it will make the circuit to the starting contactor only when depressed. If yours is rigged like others I have (and have seen ) you need to press the start button and hold it for a few seconds for the feed pressure to build, then the pressure switch will activate and keep the circuit to the contactor alive. If you have air in the line it will cause a pressure drop and the contactor will drop out stopping everything.

The pressure switch will also likely start a timer that will bring in a circuit to start the high pressure pump, with a time delay to allow the feed pump to fill the high pressure pump body so it does not start dry.

You could re-invent this kind of a circuit but I would go with the comments above... restore it to the factory original.