Measuring pool piping water flow and/or pressure

[apostolakisl]

One has been running several years and no failure yet. It looks like the from must be made from stainless steal because not even a small bit of rust.

Good to hear. Do you know what exact make/model you are using? I would be interested in monitoring my well pressure remotely, it would make adjusting my sprinkler a lot easier if I could bring up the current well head pressure on my phone.

I am only familiar with these because I had two of them fail on one of my vehicles. They both started leaking oil, then shorted. GM seems to have fixed it because the third has way outlasted the first two combined.

 

[apostolakisl]

This is a device that is exactly spec'd for your purpose. It is a little more pricey, but not outrageous. You might find it cheaper elsewhere. It is has a .5 to 4.5 v analog output that corresponds to the pressure.

http://www.shoppumps.com/Goulds-9K519-Aquavar-Aquaboost-Pressure-Transducer-p/9k519.htm

Edit:
Here is another option, less expensive but I think still spec'd for your type of application.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=250424091752+&clk_rvr_id=240363893391

 

[JonW]

I can't tell from the picture or description, does this provide me with an analog value, or just an on/off whenever flow is detected?

As for the heater idea, I installed solar heaters, so there isn't any hardware in place (yet).

I can't answer with 100% certainty, but I do believe it was only a two wire hookup that gave flow on/off.

 

[jumbodogs]

I put this in my skimmer ... if the water level drops pump turns off. $2.85

 

[Steve]

I guess when it comes to this I am old school. I think the best way to avoid that situation is to always have at least 2 inlets to the pump open (not sure if that is an option on above ground pools though?) Do you have a main drain or vac line or some other input to the pump? If so I would just crack that open a little so if skimmer stops you still have some water flowing. I've had similar when water level drops below skimmer level, it will still suck some air but it will have enough water from main drain to keep pump from cavitating.

 

[mustangcoupe]

I guess when it comes to this I am old school. I think the best way to avoid that situation is to always have at least 2 inlets to the pump open (not sure if that is an option on above ground pools though?)

Most if not all above ground pools have 1 input to the pump from the skimmer only.

 

[murphy]

I have no swimmingpool, but also problems with air in my watersystem for the irrigation.
So I build an airtrap near the pump.
Glued together from 2"-PVC.fittings.
Inside there is a small swimmer, indicating the presence of air.
And some outlets for measuring the pressure and releasing air by a manual valve.
One outlet on top goes to a solenoid which is actuated whenever the inside swimmer is indicating air.
The solenoid is controlled by an ELK-system, but any other system can do the same.
This I improved in May 2011, so I cannot report any long-time-reliability or long-time-success.
Before there was a mechanical automated venting device on top of the airtrap.
But this was not reliable enough.
Maybe because the system partly was producing more air than the (mechanical) operated vent could release.
Now the air-release is more powerfull and -more important- I also can stop the pump for some time as there is air inside the trap.

For solenoids I made good experiences with

http://stcvalve.com

Floatswitches I was buying in Germany but found a similar collection at

http://www.aquahub.com/store/floatswitches.html
http://www.coolon.com.au/download/DS_CL4L.pdf

 

[apostolakisl]

Did you make that pvc piece with the 1/4 inch side pieces comming off? I have never seen something like that.

 

[murphy]

Did you make that pvc piece with the 1/4 inch side pieces comming off? I have never seen something like that.

Yes, I glued it together from 2" fittings.
2" inside was necessarry because I didn't found a smaller swimmer-switch to indicate air.
The main pipes of my (jet-pump) watersystem are 1", 1 1/4" and 3/4".
In that artifical 2"-housing I cutted some 1/8" and other NPT-threads.
On the bottom there is a 1" NPT-thread from a ready-bought PVC-fitting.

 

[JimS]

The suggestion about monitoring amps on the pump is a good one. If the line gets plugged up and the pump is working against higher pressure, the amp draw will go up. I wouldn't be surprised if it wasn't a good correlation between psi and amps. You might even be able to convert that amps to psi.

While monitoring amps is a good idea the amps don't go up with blockage - current actually goes down - I have measured this many times. It seems like it might go up but consider the work being done. With the pump completely blocked the flow is zero. Pressure is high but no water is being moved so the loading on the pump goes way down. Same is true of many air blowers. Some units have cautions against running them with no back pressure as this overloads the motor - a huge volume of air/water is moved. Even with the lower pressure the power is greater.

 

[Sandpiper]

While monitoring amps is a good idea the amps don't go up with blockage - current actually goes down - I have measured this many times. It seems like it might go up but consider the work being done. With the pump completely blocked the flow is zero. Pressure is high but no water is being moved so the loading on the pump goes way down. Same is true of many air blowers. Some units have cautions against running them with no back pressure as this overloads the motor - a huge volume of air/water is moved. Even with the lower pressure the power is greater.

I agree. I saw this post earlier and almost commented then, but I wasn't in the mood for conflict. Amps to a motor is almost directly proportional to power produced by the motor. When flow stops, the power output goes down not up, as power output is directly proportional to pressure times flow. A high number times 0 is 0.

 

[scorp133]

I put this in my skimmer ... if the water level drops pump turns off. $2.85

Just ordered a few of these. Wish I had seen it earlier, last week the side of my sand filter ruptured and I didn't noticed till half my pool was drained. My pump is connected to a UPB switch, so it will be really easy to add this to turn off the pump if there's no water in the skimmer basket.

 

[apostolakisl]

While monitoring amps is a good idea the amps don't go up with blockage - current actually goes down - I have measured this many times. It seems like it might go up but consider the work being done. With the pump completely blocked the flow is zero. Pressure is high but no water is being moved so the loading on the pump goes way down. Same is true of many air blowers. Some units have cautions against running them with no back pressure as this overloads the motor - a huge volume of air/water is moved. Even with the lower pressure the power is greater.

Curious, this must depend on the type of controller the motor is using. If the motor has an rpm controller on it that attempts to maintain consistent rpm, then a blockage would cause it to send more power to the motor.

If the motor has no controller on it, it would make sense that less resistance would allow rpms to go up and thus draw more current.

 

[JimS]

Curious, this must depend on the type of controller the motor is using. If the motor has an rpm controller on it that attempts to maintain consistent rpm, then a blockage would cause it to send more power to the motor.

If the motor has no controller on it, it would make sense that less resistance would allow rpms to go up and thus draw more current.

I agree that it is curious - what happens is the opposite of what most people would think... But do you have any data to back up what you think will happen?

I design motor controls and have many years experience with pumps - what you are saying is simply not true. Doesn't matter if the motor is constant speed (RPM controller), or more typical induction motor, and for most other kinds of motors. It won't apply to constant displacement pumps and probably a few others but we are talking about centrifugal pumps like used on pools, wells, etc. If you don't believe me then do a test - take a pump, measure the current; then restrict the outlet and measure the current again. The current and power will go down considerably for almost all kinds of pumps, motors, and controls. There are some controls that maintain constant flow that will increase current/power but those are rare for these types of pumps.

 

[fwd03]

It is not too hard to build one by using a PVC pipe.
Seal the top of the pipe so that it is air tight.
place a table tennis ball with magnet in it.
Connect this pipe verticly at the pump outlet side.
When pump is one with good water flow, the water pressure will push the ball up.
Use a reed relay you can pickup where the ball located.
If pump is clogged, the water pressre reduced, the ball will be lower.

So in your software logic, you can control the pump on for 10 seconds (so that the water pressure can build up on the outlet side), then check if the ball is at the ideal location. If not, shut off the pump.