Magmeter problems

[TwoBlocked]

Got a call out to a frack truck filling facility. Only one of 6 fairly new mag meters were working properly. One had a burnt card, two had RS-485 failure, and two were reading only half the flow. The two reading half flow is what I am wondering about. This is reused fracking water after going through weir tanks. It was suggested to me that the electrodes in the meters might be sludged up, giving a false reading. I'll try to contact the manufacturer tomorrow for recommendations.

Anybody seen this sort of problem with mag meters? These are Isoil brand.

 

[rlundsrud]

What type of output do they have? I've had issues with badger meters that use a pulsed output for revenue grade metering. The pulse width was only 15 milliseconds, the controller that was reading the pulse took 150 milliseconds to scan all the inputs. We would only see about 1 out of 8 pulses, the controller had to be scanning that input when the pulse was still on. I ended up using a monostable multivibrator circuit to increase the pulsewidth to 175 milliseconds thus ensuring every pulse was scanned. The longer pulse wasn't at risk of overlapping another pulse as it pulsed once for every 10 gallons of water. It wasn't possible for 20 gallons to go through in less than 175 milliseconds.

 

[TwoBlocked]

We are using RS-485 Modbus. Turns out that another site with the same mag meters is having similar problems. I'll probably go out there later this week. Was looking at the possibility of using pulses. Our controllers (ABB Totalflow) have high speed counter cards available that we would install. Maybe your controllers have that option, too.

 

[tortuga]

Does the water meet the the meter minimum conductivity threshold?
Is the pipe always full going past the meter?

 

[TwoBlocked]

Does the water meet the the meter minimum conductivity threshold?
Is the pipe always full going past the meter?

It should, since it is brackish frack water. As far as being always full, I wondered about that. The trucks are being loaded from gravity tanks with vacuum assist from the trucks. Most of the piping is underground. I don't know if everything was pressure tested. I suppose there could be places that air could get sucked in. I think these have a pipe-not-full-signal that I may be able to read on a Modbus register. Thanks for the thought path.

 

[neault]

Sometimes, magmeter suppliers will specify a ground connection to the fluid, either by the metal pipe or ground rings.

 

[TwoBlocked]

Sometimes, magmeter suppliers will specify a ground connection to the fluid, either by the metal pipe or ground rings.

These are provided with ground points on each flange, both of them are grounded as required.