I'm trying to figure out the best way to control the amount of water in a container, this container will be used to add and remove weight from a vehicle. I will be using a reversible pump to pump water in and out, but was wondering the best way to keep track of how much water is going each way. The container will be a set size (say 50 gallons) so could i measure water coming in and out and record this to the LCD? Or do the water sensors only measure water in one direction and i would need to use two separate sensors? the containers are bags so they cannot hold any float or in water sensor. I was playing around with the idea of using a weight sensor as well, but the weights i would be measuring will be between 500 and 1000 pounds and i don't know if they even have a sensor i could use that would measure that much weight, or if it would even be accurate.
Using flow sensors is going to be problematic in the sense that you will need to calculate flow rate x time flowing to obtain an amount for the water transferred. Weight sensors are probably not realistic either. The former is only tricky , the latter is probably too expensive or impossible so it looks like your stuck calculating flow in both directions.
It would certainly help if you could do a calibration run with a known volume to compare measurements taken and flow-rate calculated with actual values.
I was thinking just running x amount of time based on how much water was needed, but i feel like this would need to be calibrated often if a filter was dirty or if a pump impeller was wearing ETC. I guess maybe i could use a flow sensor on each inlet to alert when flow is under a certain number, then i could inspect the equipment. If i use a reversible pump, will a flow meter work in reverse as well, or is the reading going to be off if water is going backwards through the sensor?(I'm assuming they flow sensor is directional, unless they make a bi directional flow sensor?)
You DO understand that by definition , a CALIBRATION run is a run performed with a KNOWN amount of water. The drain & fill sequence is repeated . After each run the code is adjusted to obtain more accurate results. This run, adjust ,repeat cycle is continued indefinately until either you obtain a correct value with the software , or you abort the run because something is not working the way it should (like the flow sensors).
Yes, that makes sense, I'm just thinking out loud. I guess i need to buy a flow sensor and play with it, I'm thinking my best solution will be to time the filling to a certain size (so if i wanted 3 settings 500lbs 750lbs and 1000lbs) I would just have a timer set for each setting to run the pump that long. I would get a base flow rating, and set a threshold for a warning message when the flow is under that rating ( maybe a filter is clogged or a impeller is getting worn on a pump) I'm hoping the flow sensor will work equally in forward or reverse which would make it easier to program.
It would be more important that the flow sensor was consistent in each direction than that it worked the same in both directions - you will probably need to calibrate it separately in each direction.
Since the fill flow sensor and drain flow sensor are separate sensors, even if identical, the accuracy may differ , which is , I think why Peter is recommending that they both be calibrated.
How are the containers/bags going to be supported? If they're suspended, or supported by a platform/support which could be allowed to move, then it would be possible to take the weight with a preloaded element which would deflect when the weight exceeded a threshold. You could use that either as a visual prompt to stop filling, or to operate a switch to indicate the full level.
raschemmel:
Since the fill flow sensor and drain flow sensor are separate sensors, even if identical, the accuracy may differ , which is , I think why Peter is recommending that they both be calibrated.
I was planning on using a single reversible pump for each container, in this case it would only be one sensor for each bag
PeterH:
It would be more important that the flow sensor was consistent in each direction than that it worked the same in both directions - you will probably need to calibrate it separately in each direction.
I ordered a flow sensor so im going to get it and play around with it when it comes in, from what i can see it doesnt look directional so i will setup a mock environment and see what kind of readings i get.
GoForSmoke:
You could measure how full the tank is.
since the container is a bag, not sure what kind of sensor i would use
PeterH:
How are the containers/bags going to be supported? If they're suspended, or supported by a platform/support which could be allowed to move, then it would be possible to take the weight with a preloaded element which would deflect when the weight exceeded a threshold. You could use that either as a visual prompt to stop filling, or to operate a switch to indicate the full level.
The bags will be sitting in a compartment, they wont be suspended, i was playing around with the idea of building a weighing platform of some sort, but i don't think i could do that very cheap for the amount of weight I'm going to be having.
I wasn't thinking of a weighing solution - just a preloaded mechanism that would yield slightly when the target weight was reached - you could think of it as linear force version of a torque wrench. It would just need a spring with a stud through it to give it a preload. It's only carrying half a ton or so - it's not going to need anything heavy.
PeterH:
I wasn't thinking of a weighing solution - just a preloaded mechanism that would yield slightly when the target weight was reached - you could think of it as linear force version of a torque wrench. It would just need a spring with a stud through it to give it a preload. It's only carrying half a ton or so - it's not going to need anything heavy.
i see what you are saying, the only issues is moving and bouncing around i think could cause it to trigger to early, and it would have to be under the weight.
GoForSmoke:
Suppose you filled your bags from a tank/barrel with known volume?
i will be pulling from the lake, its actually for a boat so i don't think that would work.
there are multiple types of flow sensors.
a weir tube measures the height if the fluid in the tube, based on time of flight, you can calculate or monitor the flow rate.
you can have a set volume fill, then dump. that is a one way device. maybe (think h-bridge to alter destination)
like fill a five gallon bucket, then drain it. tipping bucket rain gauge ??? monster style.
since water is non-compressible, the density will not change under pressure. an orifice at pressure will pass a known quantity. so you could control the pressure discharge of the pump through and orifice and calculate time to determine quantity.
you could use a positive displacement pump, much harder than some of the options, but might be a deal on e-bay.
as for the possible flow sensor, you can use a flow sensor on the pump, then alter the source and the discharge. (With all the H-bridges we do to control electrons, a couple valves to control water have been mentioned earlier. : )
I think the big questions are if you have a huge budget and how long you want this to take.
a garden hose sensor with diverter valves (h-bridge) would be pretty simple and pretty accurate, but could take a long time.
a fire hose sized valve/sensor would be pretty costly !
Actually you could put a barrel over the side but you're in a BOAT that you can trim level and measure from gunnel to water surface or put a strip down the side to make an electronic water line.
Any good direct means of measure beats indirect means especially when multiple measures and estimates occur.
You're probably not going to like my suggestion but in this particular case I recommend you call several plumbers. Explain what you are trying to do . Ask them if they can do it and what they would charge. Tell them they have to supply the parts. Offer to pay half in advance , the balance on completion it the quote is reasonable. Tell them final payment only after demonstrating it works. If you
don't like the quotes, do it your self but sometimes it helps to ask an expert. You could also offer to pay a smaller fee for the solution design and part to implement it and you do all the labor. What you have not doesn't sound workable with that reversable
pump. You would have to insert a pair of valves in the line with one going one direction and the other going the other direction with shutoff valves to block the unused direction.