Fusor Forums

I think one benefit of electrolysis at home is no hazmat or freight shipping issues.
Same can apply to using deuterostiks at home, if some enthusiast starts a filling service.
Can items be listed on ebay with a price that includes refundable core fee? - Rich Feldman

Would anyone be interested in purchasing D2 filled cartridges for the following cost + shipping
Filled Brunton Hydrocore / Horizon Hydrostik PRO cartridge containing ~2g (~11L) of D2 = $115
Cartridge refill for ~2g (~11L) of D2 = $65

I would go for that.
But promised myself not to work on deuterium before I have an operating vacuum chamber again.

Cartridge connectors and pressure regulators are easy to get on ebay, but I would first look into hacking the Brunton fuel cell unit on hand.
viewtopic.php?f=10&t=11147&p=73509&hili ... ted#p73509

Recently did some more development on the proportional valve pressure controller. I have the proportional solenoid valve working open loop with both air and hydrogen with very promising results. The drift is less than the piezo valves I was using previously, and they don't require a high voltage source. The end goal is to have an arduino controller query the presser over an rs-485 connection to the vacuum gauge and run a digital PID control loop to stabilize pressure.

This was using the clippard ET-PM-10-0925-V proportional valve $67 ea from http://www.gocfa.com
https://www.clippard.com/part/ET-PM-10-0925-V
and the EVPD-2 valve controller $276 from clippard, however any current driver will work (or voltage source if you are willing to accept a slightly non-linear response)
https://clippard.com/part/EVPD-2

Ion source testbed mounted on dry turbo station MKS 901p piezo/pirani gauge Clippard valve mounted on 1.33CF flange valve controller, taking a 0-5v analog input signal pressure when stepping input voltage to controller

Andrew, a plus-ultra setup! Very nice indeed. Nice plot on pressure as well. Were those wide ranging pressure regimes under you new control setup? We look forward to future posts on this system.

Richard Hull

plots are for open loop control of the valve stepping through different input voltages on the driver.

latest tests using a Recom RCD-24-0.30/W/VREF LED constant current driver ($18) to run the valve instead of the more expensive Clippard EVPD-2 driver.
https://www.digikey.com/en/products/det ... EF/2612667
you can also get them as free samples:
https://recom-power.com/en/rec-s-RCD-24.html?0

The LED driver does not have the scaling functions that the clippard driver has so the programming voltage to the driver to command pressured between 1-10mtorr is only a several hundredths of a volt wide, id does work as a valve driver though, at much lower cost. The clippard driver does work better out of the box, but the led driver certainly could have an op-amp or resistor scaling network put before the input.

Latest tests:

Charging pressure from hydrofill pro is about 270psi for steady state operation, this is just the output pressure from the fuel cell, no compressor is used.
Over a 1h run blanked off against a pressure gauge: for the first ~10min no D2 is produced, then pressure climbed rapidly to 300psi over 2min, then slowly to 335psi over the next two min, then slowly dropped to 270psi over the next 10min and held that pressure until it was turned off. I know it has a pressure sensor inside, possibly a digital pressure gauge though it may also be a pressure switch. It says the rated output pressure is 435psi and it never reached this level, it's possibly the microcontroller has some intelligent gas pressure regulator to determine the best output though. Metal hydride cartridges have an outlet pressure of ~250psi

Amazing! Your own little tank of D2 at a pressure that will allow for many runs of a stock fusor. A very nice and for sure a rather costly little system that you have reported on before. While I have a larger tanked system and two PEM cells, if needed in future, your system is sort of a middle ground that in many ways is ideal.

Richard Hull

More tests on the Hydrofill PRO.

The circuit boards have a KA7500 switchmode controller chip running a buck converter connected to the fuel cell. and an Holtek HTT46R066B microcontroller. The The pressure switch is digital and is connected to pin 16 of the microcontroller (a digital i/o line). The switch pulls the i/o pin high to 5v when closed. Measurements on the fuel cell indicate a voltage between 3.06V-3.2V and current between 7.9A-8.75A. Connecting the switch i/o pin to 5v through a 2k resistor turns off fuel cell current. Doing this a few times shuts down the fill cycle on the cartridge (turns the status light solid green, shuts down fuel cell current). I believe the purge cycle on the molecular sieve hydrogen purifying column is triggered through a timer and not a pressure sensor. The cartridge connector on the Hydrofill has a check valve on it so venting the water trap / molecular sieve column does not empty any deuterium from the cartridge. There is no pin on the fitting to open the cartridge valve so it is opened by pressure alone.

Circuit Board front/back Current measurement on cell

Thought I would revive this thread now that I see deuterium lecture bottles have doubled in price ($800 plus shipping hazmat).

Has anymore work been done with these? Any chance someone with one of these might be willing to fill a hydrostik if we supply the hydrostik and the heavy water?

I can’t see myself paying $1k for a lecture bottle once mine runs out…

-Matt

I've been using these for a while now and so far have been working great, much easier than messing around with the syringe and pem arrangement. Each one lasted many months and the refill station has worked well. I got a ridiculous quote of £1300 + shipping for a normal gas bottle here.

Pretty sure Andrew is still able to supply filled cartridges - although the powers that be didn't seem to like these being shipped internationally. I'm also happy to supply these at cost for any UK folks, they work out about £100 each.

Hi Emma,

What are you using for a regulator on the hydrostik?

-Matt

I'm using the Horizon one, it screws onto the cartridge and it drops the pressure right down:
https://www.h2planet.eu/en/detail/one_s ... egulator_1

Same one as in the photo at the top of the thread.

Each recharge using the refill station about 30g of D2O.

The purge solenoid on my Hydrofill unit failed, fortunately it's pretty easy to find on ebay. I have 2 backup electrolyzers so not an issue for deuterium generation, but hopefully I'll have this one fixed
It's a 3v, 10ohm coil, with a normaly closed config
https://www.ebay.com/itm/262673367726 While I had the unit apart I decided to replace the silicone hoses which were degrading and examine the other components inside. All the hose connections are o-ring sealed with a washers compressing a rectangular o-ring against the stainless tube and the seat of a threaded fitting. They are pretty east to remove. This unit turned out to be a combination of a reservoir to collect water that made it through the electrolysis, and a pressure regulator to limit the pressure the purge solenoid must handle. The output is over 300psi, but the solenoid is probably limited to about 10-20psi. When the solenoid opens any water in the reservoir is forced out. The other cylinder as expected appears to be some manner of molecular sieve for purifying the hydrogen/deuterium. Appears to have some sort of relief valve on the bottom x-rays show some powder inside and you can hear something granular when you shake it

I noted earlier last year, I think, that the price of heavy water has definitely more than doubled in the last decade. Are production costs increased? There is a limitless supply on earth of raw material (water). I might imagine labor costs, regulations and the electricity demanded in production have increased. I would hate to think someone, entity, nation state, etc. is building up a stockpile of D2 gas or heavy water and bidding the price upwards as it comes on the market. Supply and demand. Same goes for tanked gas as D2 gas isn't found in nature and must come from electrolysis in the end.

Richard Hull

Unfortunately it seems this electrolyzer has died (fortunately I have 2 more). The replacement solenoid valve did fix the problem, but it stall wasn't producing deuterium at anywhere near the rate it should. It was producing 0.3l/h and should be producing 3l/h. Blanked off against a pressure gauge, the cell would still produce about 400psi output but at very low supply rate. Cell voltage was at the maximum 5v the board could supply and it was only drawing a few hundred mA. Connecting the cell directly to a power supply required 12-13V across the cell (normal voltage should be 2-3v) to drive the required ~8A. At this current the cell would produce the required 3l/h but would rapidly overheat due to the increased power dissipation. This effect points to PEM membrane degradation (see fig 2) in following paper.
https://h2tools.org/sites/default/files ... er_194.pdf
I decided to dismantle this unit for exploration an possibly future repair. The fitting the hydride cartridge screws into also has a pressure relief valve on the back that was not previously visible.
The PEM cell has an M5 output thread, which will also fit a 10-32 face seal pneumatic fitting rather than the internal o-ring they designed. The bolts holding the steel plates (1/4" thick on the water side, 1/2" thick on the deuterium side) were torqued to about 16 in-Lbs as assembled. Halves are sealed with a silicone o-ring There is an array of channels to allow water access to the cell electrodes and membrane. The electrode feed throughs are sealed with RTV The output fitting is stainless and has a fiberglass backup washer The metal mesh electrode is spot welded to another finer metal mesh and lays on top on another fine metal mesh. These electrodes have some oxidation (rust?) on them and the water in the electrolyser was starting to get a very fine rust particulate material in it when the electrolyser was run. The good ones don't have this issue. Under this electrode is the polymer PEM membrane The OEM membrane is bonded to a graphite cloth presumably impregnated with a catalyst. The membrane surface abuts an o-ring that steels it against the opposing electrode to trap the deuterium, a hole drilled through the stack to the other end allows deuterium to diffuse to the center and exit the electrolyzer A rigid graphite plate contacts the graphite cloth on the membrane The sealing o-ring is removed The negative electrode is bonded to a graphite cloth that contacts the graphite plate The hole through the electrode allows the deuterium to exit and is sealed to the output fitting with an o-ring Resistance measurements are as follows Does anyone have a guess on the exact type of membrane?

Outstanding disassembly sequence/photo's and diagnostics.