Amp Meter Recommendations

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Ravenvalor

Ravenvalor

Senior Member
Location
Triad region of NC
Occupation
Electrician
Will someone kindly recommend an accurate clamp-on amp meter that ranges down into the milliamps? My restaurant customer just spent $2,000.00 to have 2 - perfectly good gas regulators replaced.

Thanks for the help.... :)
 
190209-0850 EST

Ravenvalor:

What is a gas regulator? Is it a solenoid valve? Is it a pressure regulator? Is it both? Is it a servo valve? Is it AC or DC? How much current? Are wires separate or in a cable? Why the need for a clamp-on?

What is the wire size to the regulator, and how long?

.
 
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I use a Fluke 87 in series with the load.

I suspect a clamp for ma would be rather useless for 99.99% of our work.

Typical for Gar, he raises a lot of questions.

My need to know is why you think a clamp on ma meter would have prevented the replacement of pressure regulators.
 
Thanks for the help gar....

gar said:
190209-0850 EST

Ravenvalor:

What is a gas regulator? Is it a solenoid valve? Is it a pressure regulator? Is it both? Is it a servo valve? Is it AC or DC? How much current? Are wires separate or in a cable? Why the need for a clamp-on?

What is the wire size to the regulator, and how long?

.
Click to expand...


What is a gas regulator? It turns off gas to the grill in the event of a fire or the hood exhaust fan turning off.

Is it a solenoid valve? It is a solenoid.

Is it a pressure regulator? Do not know if it is a pressure regulator.

Is it both? Unsure.

Is it a servo valve? Unsure.

Is it AC or DC? AC 120 volts.

How much current? Unsure. Very low.

Are wires separate or in a cable? The wires are separate, a hot and a neutral.

Why the need for a clamp-on? So that we can check the current draw without turning off the grill during restaurant's busy times.

If we can check the current draw with the draw listed on the solenoid we can determine whether or not valve is fully opening or just partially opening. A clamp on milliamp meter will allow us to do this without shutting down the grill.

What is the wire size to the regulator, and how long? A 20amp, #12 gauge circuit is about 50' long in total length.
 
190209-1017 EST

Ravenvalor:

Copper wire has a resistance of about 1.6 ohms / 1000 ft. Thus, 50 ft is about 1.6/20 = 0.08 ohms. A typical solenoid valve is easily in the 1 W or so range. 1 W at 120 V is about 0.008 A, but current will be at least somewhat greater on an AC coil. Assume 10 mA. 0.08*0.01 = 0.0008 or 0.8 mV.

With a 50 ft long test lead across a 50 ft long piece of #12 copper what is my noise level. A Fluke 87 alone with shorted terminals is about 20 microV, or .02 mV. Would this work I don't know. One would need to see what the total noise level was with no current in the #12 wire.

Check that my calculations are correct.

I can expect that a failing to close AC solenoid (opening of valve) will have a somewhat to much higher current in the partially closed state compared to the closed state. Most AC solenoid valves burnout if they fail to fully seal.

My Fluke Hall device AC-DC clamp current probe has an output of 2 V at 20 amperes. Or 1 V = 10 A.

I am going to move my location, then will return.

.
 
Just because the solenoid valve is drawing current doesn't confirm you will have gas flow, just tells you the coil is intact and drawing current, how much current may also tell you the armature it drives has "pulled in" or not, but won't tell you if anything attached to it is attached and functioning.

I suggest if you want to verify gas pressure on output side of the valve you need to have a pressure test port in the line, and if needs checked often enough even a permanently installed pressure gauge.

I don't think you will find accuracy to be all that great for mA ranges with a clamp on meter.

another thing that can be done is to loop conductor multiple times through your clamp. Ten loops will give 10x reading on the meter. If you intend to check this on a regular basis cable tie such a loop together so it is quick and easy to clamp on to check.
 
Ravenvalor said:
My restaurant customer just spent $2,000.00 to have 2 - perfectly good gas regulators replaced.
Click to expand...
Seems one could have found a way to shut down long enough to open the circuit and perform continuity test and even insert in line ammeter before spending that much on parts you aren't certain are needed.
 
190209-1058 EST

Ravenvalor:

With my Fluke Y8100 DC/AC Current Probe (not made in a long time) and a Fluke 27 the AC noise level is around 2 mV, or 20 mA. On DC I can't balance closer than about 6 mV, or 60 mA.

An AB #2 motor starter from the 1960s, a good size solenoid, is about 10 mV when sealed in, or about 100 mA. This is clearly detectable wiith the hall probe, accuracy won't be good.

With a Fluke Y8101 1000 to 1 current transformer I read 0.25 mA on the Fluke 27 with the AB sealed in. Thus, 0.25 A. Noise level with this probe is very much lower. Even on the microA range noise was not high.

With a Kill-A-Watt reading the AB sealed in the curremt is 0.26 A, P = 9 W. and VA = 36.

A $1000 valve is going to be a fairtly good size or overpriced.

,
 
kwired said:
Just because the solenoid valve is drawing current doesn't confirm you will have gas flow, just tells you the coil is intact and drawing current, how much current may also tell you the armature it drives has "pulled in" or not, but won't tell you if anything attached to it is attached and functioning.

I suggest if you want to verify gas pressure on output side of the valve you need to have a pressure test port in the line, and if needs checked often enough even a permanently installed pressure gauge.
Click to expand...

That's kind of what I was thinking. Plus an electrician wouldn't be the best to troubleshoot something like this.
 
growler said:
That's kind of what I was thinking. Plus an electrician wouldn't be the best to troubleshoot something like this.
Click to expand...
Electrician should be able to confirm power to the solenoid, and that the solenoid is/is not drawing current. Beyond that, might not be something he is qualified to do. When troubleshooting you may cross over to some extent in finding out what is wrong, but could still end up getting someone else to verify what you found and actually change the gas valve or look into other gas issues.
 
kwired said:
Electrician should be able to confirm power to the solenoid, and that the solenoid is/is not drawing current. Beyond that, might not be something he is qualified to do. When troubleshooting you may cross over to some extent in finding out what is wrong, but could still end up getting someone else to verify what you found and actually change the gas valve or look into other gas issues.
Click to expand...

If you have some reason to think there is a problem it the gas regulator.

On a problem like this I would think that someone familiar with gas supply lines to make sure the correct volume of gas was getting to the grill.

Earlier he mentioned they needed to check during the busy part of the business day. This could mean they are not set up to supply enough gas to start with. You would need to know what all is connected and the amount of possible gas usage.
 
growler said:
If you have some reason to think there is a problem it the gas regulator.

On a problem like this I would think that someone familiar with gas supply lines to make sure the correct volume of gas was getting to the grill.

Earlier he mentioned they needed to check during the busy part of the business day. This could mean they are not set up to supply enough gas to start with. You would need to know what all is connected and the amount of possible gas usage.
Click to expand...
Right, and someone that knows how this works and how to troubleshoot it should have verified the gas valve wasn't working before spending 2 grand on (apparently) two of them. You can throw all the parts at it you want, it won't fix an inadequate supply if that is what is going on.

Pressure check on supply side of valve in question could have verified something upstream is the issue, I'm not a gas guy but can figure that out.
 
Ravenvalor said:
Will someone kindly recommend an accurate clamp-on amp meter that ranges down into the milliamps? ...
Click to expand...

I've used a Fluke 368 (I think - might have been an older model) for trouble shooting heat trace leakage. As I recall it was good down to sub-milliamp.

$600 sticks in my mind. But that was a few years back
 
iceworm said:
I've used a Fluke 368 (I think - might have been an older model) for trouble shooting heat trace leakage. As I recall it was good down to sub-milliamp.

$600 sticks in my mind. But that was a few years back
Click to expand...
Was it a clamp on?
 
Thanks for the great help....

The tech sent out was the Fire Control Suppression System Tech. Before he was sent there they had others go out there and verify that adequate gas was getting to the regulators.
The regulators were the next step for deducing the problem in their minds. The FCSST deduced that one of the regulators was working properly but suspected the other was not opening up enough. They had me out there to assist him in anything electrical because he was not authorized to work with electricity. He had a couple of regulators in his truck so he decided that both the good one and the suspect one should be replaced.
He left us there with the regulators and we waited til after the restaurant closed for the plumbers to show up and replaced them while we were there to disconnect the old and connect the new regulators. After replacing them the problem was not resolved so the plumber opened up a union at the grill and determined there was little to no gas getting to the grill. He immediately assumed that the problem was either a small hose, a smaller regulator or a cutoff valve located on the back of the grill.
I was hoping to avoid this problem in the future by having a meter that can tell me if the valve is working properly or not but you have convinced me that it takes more than a meter.
As far as the FCSSTech recommending replacing the regulator is concerned- it seems like the old adage "If you have a hammer everything looks like a nail." may apply here. However he is a seasoned tech and has seen many regulators in his years. He probably thought it prudent and I will not judge him on this choice.

Thanks again....
 
Ravenvalor said:
Why the need for a clamp-on? So that we can check the current draw without turning off the grill during restaurant's busy times.

If we can check the current draw with the draw listed on the solenoid we can determine whether or not valve is fully opening or just partially opening. A clamp on milliamp meter will allow us to do this without shutting down the grill.
Click to expand...

kwired said:
Right, and someone that knows how this works and how to troubleshoot it should have verified the gas valve wasn't working before spending 2 grand on (apparently) two of them. You can throw all the parts at it you want, it won't fix an inadequate supply if that is what is going on.

Pressure check on supply side of valve in question could have verified something upstream is the issue, I'm not a gas guy but can figure that out.
Click to expand...

I have agreed with your idea of pressure testing from the start.

For some reason they don't want to shut the grill down. I can understand that during the busy times but that just means that someone will have to troubleshoot after hours.

Sounds like they have already changed out the gas regulators and while it's possible to get a new bad part it's not all that probable.
 
kwired said:
..I suggest if you want to verify gas pressure on output side of the valve..
Click to expand...

Yes, plumbers equipped for gas piping should have pressure testers.

Appliance installers also demo perfectly good gas-pressure regulators.
If new appliance is warranteed, they don't want old regulators in the mix.
 
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