Pump System non PLC control

robcontec

Member
Join Date
Feb 2007
Location
Bloomfield Hills, Michigan
Posts
25
I'm looking for a solution to a problem we are having in our water treatment system.

We add a lime slurry to the water prior to it going through the filtration process.

The slurry is is hand made.

With out going into too much detail, the Control system running the filtration process is taxed to the limit.

With in a year the whole filtration system will be replaced


What I need to do is pretty simple.
For every bag of lime that is added to the slurry tank 100 gals of water needs to be added.

The issue is that the water is added by an operator opening and closing a valve.

The problems is that some times the operator gets called away and doesn't shut off the water (I'll only be gone a minute).

What I am looking for is a 110 VAC stand alone system that will add the 100 gals and shut off.

I was thinking about a home sprinkler type timer to control this (xgals/min type a thing.

This would of course require the operator to think and we can't have that.

I am open to suggestions, but would like some thing that could measure flow rate then shut off when the require amount of gals is reach.

Basically I want some thing that the operator would just have to push a start button them walk away.

Thanks in advance

Tom
 
What kind of budget are you talking about. I don't know any really cheap ways to do this other than to install a toilet bowl style float in the mix tank. You could put a simple solonoid valve in front of the float. Use a simple float limit to break open a relay that runs the solonoid. Install a push button to latch the relay and open the valve. Simple and cheap.
 
we need more info

I like the float idea above-gloriously simple - but we need more info.
Is this mix process continuous, or is the tank isolated when you are adding water and lime ? (and then dumped later ?)

Is the flowrate into the tank known ? or is the level in the tank reliable ? how do they know when to stop ?(the way it works now)

-John
 
A timer, and an orifice to generate a known flow might work, but wouldn't be extremely accurate.
How about something simple, a tank, a float switch, inlet valve, outlet valve, start button, and relay.
On start seal in the relay, the outlet valve closes, the inlet valve opens, until the float is satisfied at 100 gallons. At that point, the relay drops out, closing the inlet valve, opening the outlet valve, done.
 
I saw a maintenance guy put together an old fuel oil tank with a toilet float and flush valve. The tank filled to the float level, 75 gals, and when the operator needed the pre measured amount he just pulled the chain on the flush valve and flushed.
 
Something like this would do the trick.

http://www.ahs.it/en/batch-control-units/lambda-m.asp

Set how much you want, pull the handle, meter does its thing, then shuts off automatically.

I used to work in textiles and we had meters similar to that for slurry batch control.

They were larger but worked on much the same principle.

There is also another version on the page linked above that operates a microswitch for solenoid valve actuation.
 
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A simple paddle wheel flow meter with a pulse output and a counter by Red Lion or others would do the trick. I'd personally tie the flow meter to a simple PLC but the counter and a relay or two would work as well.
 
i like the toilet idea, the operator does not have to wait at all.
however i would use a switch over valve so or fill the tank or empty it, because when he is called away the water will stay flow.
it is cheap and fast, if a pump is needed then use one with a float switch.
always eqaul amount.
 
Ok, I should have been a little bit clearer. This is for a batch process mix tank.
1.) The operator puts in a bag of lime.
2.) The operator pushes the start button.
3.) The start button latches the cube relay with the stop button and the tank at level prox or limit switch in series.
4.) The solonoid opens.
5.) When the water level gets to the proper level the limit or prox breaks the latch on the cube relay and the solonoid closes.
6.) pump the mix out as needed.
7.) Repeat process as needed.
SimpleMixTank.jpg
 
The problem that I have is that the slurry tank is never empty, so the start point is not a constant.
The operator will mix in more lime as he sees fit. That is we pump the lime slurry in constantly to the water filtration system. The slurry tank may be half full 3/4 full.

The operator will check the slurry mix and add lime and or water as necessary.

The only thing I know for sure is that 1 bag of lime requires 100 gals of water.

The way they do it now is that they at the lime and then add 6" of water.

That will be the same whether the tank is 1/4 full or 3/4 full. so a fixed point like a float wouldn't quite work
 
Can you time how long it takes for the water to rise six inches (provided the water pressure is always the same)? Then rig a timer to shut off the water.
 
The only thing I know for sure is that 1 bag of lime requires 100 gals of water.

The way they do it now is that they at the lime and then add 6" of water.

That will be the same whether the tank is 1/4 full or 3/4 full. so a fixed point like a float wouldn't quite work

So make the float mounting point moveable with some sort of indication 6" below the trip point of the float. Each time they need 100 gallons, move the float up / down until your indicator (6" below float trip point) is at the existing water level.
 
I'm looking for a solution to a problem we are having in our water treatment system...




What I need to do is pretty simple...


The issue is that the water is added by an operator opening and closing a valve.

The problems is that some times the operator gets called away and doesn't shut off the water (I'll only be gone a minute).

Simplicate not complicate.

Why does the operator walk away? Is it behavioural?

If it's a manual process then why not have a valve that has to be held open by the operator?

Or tie the operator to the valve. Threaten to dangle him over the tank if he walks away again!

.
 
Simplicate not complicate.

Why does the operator walk away? Is it behavioural?

If it's a manual process then why not have a valve that has to be held open by the operator?

Or tie the operator to the valve. Threaten to dangle him over the tank if he walks away again!

.


The operator is either a Lab tech or a syrup operator. He doesn't necessarily walk away but is called away for some other issue.

Godfrey

I was looking for something along those lines, I was thinking of a lawn sprinkeler (sp) timer.
 

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