Entropy

Relax in southern comfort on the east bank of the Mississippi. You're just around the corner from Beale Street and Sun Records. Watch the ducks, throw back a few and tell us what's on your mind.
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mediatechnology
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Re: Entropy

Post by mediatechnology »

Now you need a "Cotton Region Shelter" to put the remote in.

Plans here: viewtopic.php?f=12&t=476

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BTW I read some time ago that the original Cotton Region Shelter specification required whitewash paint which is no longer available. Most get repainted in modern latex which makes modern measurements read hotter. Just sayin'...
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JR.
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Re: Entropy

Post by JR. »

I think I will pass on building a proper shelter for my temperature remote, but may experiment more with the location....

I like the idea of two sensors, but now that I have wrapped heat tape around my one pipe that froze, I feel lucky about the laundry room.

JR
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mediatechnology
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Re: Entropy

Post by mediatechnology »

Back in 2015 I wrote here that I had to replace my four-year-old kitchen faucet.
Last least year (2017) I noticed pinholes on the underside of the two-year-old faucet arm.
I replaced the two-year old faucet with an identical (cheap) one.

I began to think there might be galvanic corrosion.
The supply lines are plumbed with PEX.
Everything floats except the cast-iron sink which is grounded via the disposal third wire safety ground.
The faucet base, the arm and the handle all float relative to the sink and each other.

This morning, while bored, I decided to measure my sink's DC.

Measuring from the base to the arm, with a relatively low impedance DVM, I'm seeing approximately +200 mV DC initially.
There is a two cell battery stack from the base to arm to handle.
The best battery - the one with the highest voltage - is the base to arm with about +150 mV.
There's another 50 mV in series from the arm to the handle.
After you measure it for awhile it begins to bleed off.
Turning on the water lowers the DC temporarily.
As soon as the water is turned off the battery begins its recharge.
Positive DC on the metal is causing it to migrate and corrode.

This is why modern cars have negative DC grounds and telephone battery feeds are -48V.

Don't quite know how to bond all the moving parts together and I'm sure that more expensive fixtures have the same stupid problem.
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JR.
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Re: Entropy

Post by JR. »

Can you bond the sundry parts togher with simple screw clamps around the metal under the sink?
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or I wonder if there isn't a commercial solution if it is a common problem?

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My laundry room looks like a rube goldberg experiment with wires bonding water heater chassis, to copper plumbing (both hot and cold) and then to the fuse panel.

JR
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mediatechnology
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Re: Entropy

Post by mediatechnology »

I found an additional cell.

Grounding the base doesn't help the sections above it because the four sections of faucet galvanically float from each other.

Curiously one of the cells in the stack is polarity reversed from the rest.
The only way to equalize them is to put metal shims between the sections.
I used a piece of aluminum foil.

EDIT:

Rough voltages based on initial measurement.
The collar and ball voltages discharge during measurement.
Meter Rin is 1MΩ. Ground is referenced to the base, collar and ball.
The moving collar is the part attached to the swinging arm.
The ball is between the collar and the single handle.

Faucet base to moving collar: +33mV
Collar to ball: -350 mV
Ball to handle: +460 mV

No wonder why these things don't last. The seals insulate the sections from one another, create a dielectric/separator, the water an electrolyte and the metal parts the plates of a battery.

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JR.
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Re: Entropy

Post by JR. »

Might be time to consider a different design.

JR
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mediatechnology
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Accutronics Reverb Spring Prevents Galvanic Corrosion of Kitchen Faucet

Post by mediatechnology »

I would be willing to bet most, if not all modern faucets have this problem.
I may need to take an Ohmmeter on my next trip to Home Depot or Lowes.

Problem solved.
I took an Accutronics reverb spring (stainless IIRC) and made a collar that rides on the joint between the base and the collar.
The sink arm can still rotate.
The potential difference between those two sections drops to 0 mV due to galvanic bonding.

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A common spring prevents potential differences from developing in kitchen faucets reducing corrosion.

I can also do this to the top moving joint.
That gets three of the four pieces bonded leaving the handle.

My thought for the handle was to make a smaller cuff out of the same spring and then tie it to one of the other springs with a fine piece of wire.
The "drain" wire (pun intended) would be behind the handle and out of sight.

I really don't want to cut up this reverb spring so I'm going to see what I can find at the hardware store.

Oh and BTW I can get some much higher potential differences with hot water. Figures.
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mediatechnology
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In Search of the Equipotential Kitchen Faucet

Post by mediatechnology »

The Accutronics reverb springs sort of fell into place. The top ring is coupled to the bottom one by a section of spring behind the turret.

This ties all four sections together bringing them to equal potential. The top spring rides on the ball always seeking the smallest-available diameter.

The bottom spring rides on the groove. The faucet can be turned and operated normally and the springs ride along.

Image

I now measure 0 mV between the bottom 3 sections. The top sometimes shows 1-2 mV from the base which could be improved by cleaning the bottom ridge of the handle.

The studs underneath are grounded by a clip lead but the base floats from that. The bottom gasket insulates the base from everything below it.

There is about 300 nA DC current from the faucet to earth ground.
What needs to happen is to loosen the whole faucet, slip a small drain strap underneath it and then tighten the whole thing down.
Ground that to third wire at the disposal.

We break new ground here at the Pro Audio Design Forum. :lol:

EDIT: Forgot to mention the most trippy part: When water is not flowing the faucet is negative with respect to earth ground. When the water is turned on, the polarity reverses. No, this is not April Fools.
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JR.
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Re: Entropy

Post by JR. »

Congrats on coming up with an aesthetic solution for your potential problem. I like the way you photobombed your own picture. :lol:

I am unsure about what exactly is going on.... but that is not unusual.

I decided to make some measurements around my kitchen faucet and sure enough I measure about 65-150mV DC between my sink and faucet?? Back before I added my dedicated safety ground to my one kitchen counter outlet, I was getting mild shocks from the old floating ground and leaky protecting devices in a cheap outlet strip, but now with a relatively solid ground for the outlet, and my copper plumbing I didn't expect to find much.

Since there was 150mV between my ungrounded metal sink, and my faucet ?? if anything grounded to water, I decided to probe between the known safety ground at the outlet and everything else. Oddly I measure 0V to the faucet, but 150mV to the floating sink.

I do not have a garbage disposal so about the only thing under the sink with power is a UV lamp, post disinfectant stage for my RO water filter. The UV lamp is not double insulated from the mains, but just has an inductor in series with the UV lamp. But the lamp lives inside a glass (quartz) tube so is unlikely to be a hazard.

My faucet is not only cheap but probably original equipment from when the house was built so half a century or more, using non-metallic hose connections.

Now I see around 65mV between faucet and sink, so I decided to sniff for current. 12-15 uA with a definite polarity.

I always thought my house was magic... :lol:

JR
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mediatechnology
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Re: Entropy

Post by mediatechnology »

12-15 uA?

Wow that's a good 26 dB more than my 700 nA. :lol:

I don't think any of it's leakage. Just pure battery.
I want to put the scope on it and actually see the polarity change.
Suppose the current flow produces noise?
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