https://www.amazon.com/dp/B000FN12M2/ref=biss_dp_t_asn

I have an Lectrasan, the copper wire that joins titanium plates is failing due to corrosion in salt water.
The titanium plates are charged positive and negative and transfer 12vdc current into a brine solution tank for sterilization purposes.
The titanium plates do not wear out, the #10 gauge copper connecting wire does. The copper wire is passed through opened interleaved slots in the titanium plate, a titanium rod would simply screw into the titanium plate along a length of about 4 inches, like the copper wire does. From plate to where it connects to power wires is about 4 inches of length.

I was wondering about using titanium rod threaded into the titanium plate?
The current flow when normally functioning is 18 amps power.

Will titanium rod of that size permit sufficient amp flow to the titanium electrode plates, seeing it has much higher resistance than copper wire?

The idea is titanium rod is going to last pretty much forever compared with copper wire.

The failure mode is heat generated with current flow to the titanium plate eventually destroys the seal allowing brine to contact the copper wire, and that causes the copper wire to break down..

A new titanium electrode for Lectrasan is over $300. So financially you can understand my motivation.

 

Depends upon the resistance of the titanium rod.
Can you determine that?

 

Various wire gauge scales are in use globally. What diameter is #10 gauge where you live?

 

0.1 inch diameter for #10 copper wire, has a rating of 30 amps.
https://en.wikipedia.org/wiki/American_wire_gauge

#10 bolt size is wider than 0.1 inch. #10 is 0.19" or about 3/16"

 

https://www.engineeringtoolbox.com/resistivity-conductivity-d_418.html

 

We can do a quick dirty estimation to see if it works.
If copper is 100% electrical conductivity then titanium is 3.1% for the same size conductor. i = v/r gives us about 0.66 ohms for the total load resistance and #10 AWG is about 1 ohm per thousand foot. Measure the length of the copper conductors total length (round trip distance from power supply to load) for a conductor resistance value in milliohms for the copper conductor part of that total resistance. If your length of equivalent #10 AWG sized titanium rod is a foot then we are looking at about 0.030 ohms for that short section with about 0.030 ohms for a 30 foot copper #10 wire. So maybe it doubles the total conductor resistance but is that a problem with power transfer to the load with a total of 0.69 ohms now if you can increase the voltage slightly to compensate for the ~0.5 volt drop across the rod resistance with a rod power dissipation of under 10W?

 

https://www.engineeringtoolbox.com/resistivity-conductivity-d_418.html

Nice site can give you expected ohms for various things

https://www.engineeringtoolbox.com/resistivity-conductivity-d_418.html#Conductivity

Copper 1.724 x 10-8
Titanium 43 x 10-8

so it seems 0.19 diameter titanium rod is like a gauge 5 wire
https://www.rapidtables.com/calc/wire/wire-gauge-chart.html

And so then titanium Resistivity Coefficient (ohm m) is 0.00000043
And Cross sectional area of the conductor (mm2) is 16.7732
Yields 7.82 ohms per 1000 feet ????????????

Is that correctly down by me?
Seems like this might work?

 

We can do a quick dirty estimation to see if it works.
If copper is 100% electrical conductivity then titanium is 3.1% for the same size conductor. i = v/r gives us about 0.66 ohms for the total load resistance and #10 AWG is about 1 ohm per thousand foot. Measure the length of the copper conductors total length (round trip distance from power supply to load) for a conductor resistance value in milliohms for the copper conductor part of that total resistance. If your length of equivalent #10 AWG sized titanium rod is a foot then we are looking at about 0.030 ohms for that short section with about 0.030 ohms for a 30 foot copper #10 wire. So maybe it doubles the total conductor resistance but is that a problem with power transfer to the load with a total of 0.69 ohms now if you can increase the voltage slightly to compensate for the ~0.5 volt drop across the rod resistance with a rod power dissipation of under 10W?

Lectrasan power feeders are #4 copper wire, basically comes from battery terminals. Just like a car, when the engine runs, the voltage will be closer to 14.xx, and at a discharging load, will be 11.xx, so I am assuming Raritan built in some reserve capacity for voltage drops. When I talked to them years ago, the 12vdc electrode at normal operation is an 18 amp draw. If salinity varies, amp flow will change up and down with salinity.
Here is a picture of the thing
https://www.mygreenoutdoors.com/rar...Xmi5lcQJO9qi5ai762bpWpclLenFr4_8aAmloEALw_wcB
Wires connect at the top threaded studs. Hidden under the white plastic cover are these copper wires. The pass thru the titanium plates sideways. I was thinking replace studs and copper wires with maybe 3 titanium rods in some way. Each titanium plate would have its own rod. There are 3 plates, 2 have one charge, and one has the opposite polarity. The black goo eventually breaks its seal and the brine attacks the copper wires. I forget exactly, but this device is rated for like only 300 cycles (about 1$ per flush) before failure, so a guaranteed money maker for the company. It does work very well when it works.

I noticed the amp flow was around 10 amps which means it is starting to either get dirty or breaking down.

 

so it seems 0.19 diameter titanium rod is like a gauge 5 wire

That is for a rod, but you started out talking about a 10-32 thread. That has to take into consideration the "minor diameter" of the thread, which ends up being ~0.15 inch diameter not the "major diameter" of 0.187 inches. from that chart here - https://www.engineersedge.com/screw_threads_chart.htm To get your original 0.187 diameter you need to step up to a 1/4-20 thread.

 

I thought about whether to use the minor or major diameter and concluded that of the available characteristics, pitch diameter (about 0.169 for 10-32) would help adjust for the decreased resistance under the thicker parts.

Actually, I don't think it will make much difference. The screw will be water cooled, and its current carrying capacity will be much greater than in free air. However, I think going to the 1/4-xx size would decrease voltage drop across it, if that makes a difference.

While hypochlorous acid (effectively chlorine bleach) is quite effective as a germicide, I was worried more about the dynamics. How much is actually produced? How well mixed is the brine solution (e.g., what is the lowest concentration and contact time)? And why must the brine be "sterilized" in the first place?

 

There are 2 mixers in the tank. And the tank is subdivided into 2 compartments of a gallon each, so each flow event is treated twice. One electrode pack sits in the tank center and treats both tanks simultaneously.
Lectrasan is used to treat poop in a boat waste system.
What you start with is a macerating head with a pump that fills the lectrasan unit, then it enters a treatment cycle, duration is couple of minutes..

It can make quite a lot of bleach. When the current goes away, it turns back into salt water. A working Lectrasan destroys all bacteria, and then it can be pumped overboard.

Jumping to 1/4 inch rods is too pricey.
Plus they would not fit into the titanium plates slots.