NPT adapters 1/4 to 1/8

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Matt_Gibson
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NPT adapters 1/4 to 1/8

Post by Matt_Gibson »

Hi everyone,

Posting here as this seems like it’s probably pretty basic, I just have been unable to find much information out there…

I have a 50L lecture bottle of deuterium (yay) but have a cga350 connection on it to deal with. I picked up a nice little Matheson 3320 but see it’s got a Cga 170 inlet. This is no good. The Cga 170 uses a 1/8 NPT end while the Cga 350 uses a 1/4 NPT. Is it safe to use some sort of adapter on the inlet so that a Cga 350 can be used with this regulator? Or am I stuck trying to find a new regulator?

-Matt
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Dennis P Brown
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Re: NPT adapters 1/4 to 1/8

Post by Dennis P Brown »

Adapters can be safe on even the high pressure side; however, adapting to the high pressure side must be extremely well sealed or even the hint of a leak, will, far too quickly, empty the bottle. Regulators, like bottles of deuterium can be expensive and we often have to use what we have. While I am wary of anything on the high end but for my lecture bottle, I did do that (so much for my taking my own advice.) It worked but did required a bit more than I bargained for and I did have some very slow leakage issues requiring I shut off the high end valve all the time.
JoeBallantyne
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Re: NPT adapters 1/4 to 1/8

Post by JoeBallantyne »

All bottles of deuterium gas should have a CGA-350 connection on them.

You should buy yourself a regulator that has a CGA-350 connector on the high pressure side.

They are not that hard to come by.

Note that CGA-350 connectors use a LEFT HAND THREAD. So remember that when you first attempt to remove the cap if any on the CGA-350 connector on your bottle of deuterium.

Joe.
Matt_Gibson
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Re: NPT adapters 1/4 to 1/8

Post by Matt_Gibson »

It’s looking like it’s probably cheaper to buy a new regulator than to retro this one…Seems to be the case more often than not with great deals, eh?
Matt_Gibson
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Re: NPT adapters 1/4 to 1/8

Post by Matt_Gibson »

Okay, so I’ve been doing a little reading and ALOT of eBay-ing.

I see that two stage is ideal and that the diaphragm should be stainless steel if to be used with deuterium. What about the second stage? Does it matter as much as the first stage?

I found a very clean Matheson 8-350 (I understand that “350” means Cga350) for $50 shipped. This is a dual stage regulator with a stainless steel diaphragm for the first stage, but has a neoprene diaphragm in the second stage. Should I go for it or keep looking?

-Matt
JoeBallantyne
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Re: NPT adapters 1/4 to 1/8

Post by JoeBallantyne »

Assuming the Matheson was shipped from the factory with the CGA-350 connector on it, I think it is safe to assume that it will work just fine with your deuterium cylinder. After all, that connector is by definition for use with Hydrogen gas and its isotopes. Would be pretty stupid for a manufacturer to ship a regulator with a connector for a gas the regulator can't handle properly.

To me it sounds like you found a reasonable deal, and I would go for it.

Joe.
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Re: NPT adapters 1/4 to 1/8

Post by JoeBallantyne »

Make sure before you buy, that the regulator CGA-350 connection has a female nut. (Assuming that your cylinder has the corresponding male connection that D2 cylinders typically ship with.)

Joe.
Matt_Gibson
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Re: NPT adapters 1/4 to 1/8

Post by Matt_Gibson »

Regulator should be arriving tomorrow. Before I hook it up and open the main valve, anything that I should be checking to make sure there isn’t any leaks/malfunctioning?
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Richard Hull
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Re: NPT adapters 1/4 to 1/8

Post by Richard Hull »

I have no idea about the setup of your regulator. Some are single gauge with a pressure range of 0-20PSI off of a tank with 2000psi
Other gauges are dual gauge sets one gauge has no valve and registers tank pressure (used to see when you are getting near empty) followed by a single valve regulating the output "line pressure", like 0-20psi or such.

Regardless, you need to make sure that the output line valve is "Unscrewed" all the way which usually will cut off all gas flow from the line. Screwing in this valve will usually allow a controlled pressure on the output line.

The output line must have a valve near the end of it to allow gas to leak into the fusor.

Just make sure all valves are closed solid before cracking the tank valve. Crack the tank valve very slowly by micro amounts. If you have a significant leak or one of the valve is open, you will waste valuable gas. With a single regulator gauge, and all with the regulator valve closed and the end of line valve closed, once the tank valve is wide open nothing should happen. You can then start opening the regulator valve to pressurize the line and this will show up on the low pressure gauge associated with you regulator.

With a dual gauge, the moment the tank valve is cracked the high pressure gauge will show the tank pressure while the low pressure gauge will show nothing until you open the regulator valve to set the output line pressure to your satisfaction.

Note: Most regulator gauge sets have an indication of max inlet pressure allowed. Make sure you are in the thousand plus psi range on the inlet from the tank. All of this data with the low pressure line gauge pressure readout span to maximum should have been available when you selected your gauge to purchase.

Richard Hull
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Matt_Gibson
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Re: NPT adapters 1/4 to 1/8

Post by Matt_Gibson »

Hi Richard,

It’s a dual gauge, two stage. High pressure side/inlet goes to 3000psi and the outlet side (has a valve also) goes to 100psi. Looks to be in great condition, so hoping all goes well and I’m rubbing my cylinder tomorrow for comparison with my PEM deuterium.

-Matt
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Dennis P Brown
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Re: NPT adapters 1/4 to 1/8

Post by Dennis P Brown »

I always pull vacuum on my line/connector system up to the primary system valve that goes up to the regulator. That is, the valve I use to release gas from the low pressure stage of the regulator. Make certain that valve to the system is closed. This allows one to determine that the deuterium lines are sealed - that is, no leakage causing a rise in the fusor system pressure. Richard provides the correct methodology to open the regulator - again, your system valve used to release deuterium into the line should be closed when first doing this. Listen closely for a high pressure leak. I open, then immediately close the high pressure valve on the tank. Then record the high and low pressure gauge readings on the regulator. Then closely watch that no pressure fall occurs. Any pressure fall over a few hours means a leak.
Matt_Gibson
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Re: NPT adapters 1/4 to 1/8

Post by Matt_Gibson »

Got the regulator and not sure if what I’m seeing is okay:

I quickly opened the cylinder main valve and closed. This hit 1800 psi on the inlet side. The outlet side stayed at 0psi. I then closed the regulator valve and watched the outlet side hit 10 psi before opening the valve again. I then connected my syringe and opened the outlet side valve and watched the syringe fill pretty quickly. The outlet side pressure dropped to 0psi.

I left things alone for about an hour and have noticed that the inlet side pressure is dropping while the outlet side increasing despite the regulator being opened all the way back up. So it appears that the high pressure side is leaking into the low pressure side.

:-(
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Richard Hull
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Re: NPT adapters 1/4 to 1/8

Post by Richard Hull »

I am using a common welding regulator and have since 2000. It is NOT rated for hydrogen use! As all here know, I have been fusing very well since then.

My regulator behaves like yours. It leaks down.
Always has...Always will....

Secret to success....... I never fill on the inlet side to full pressure. It is an art of so artfully cracking the tank valve that the inlet tank pressure gauge never climbs, (due to its regulator being separately controllable), but the line gauge does. Another secret.....I replaced the low pressure line line gauge with a 0-5psi gauge. I have an old CO2 cartridge as my dead volume in the D2 line to the fusor. I allow this dead volume to fill to 1-3 psi using the tank valve once I have the outlet valve set to limit the inflow to the 0-5psi gauge. With the dead volume of the gauge set and CO2 cartridge cylinder as my (virtual syringe), I can then use my sapphire leak valve to inlet to the fusor. In short my tank valve is forever closed save to barely admit gas to fill the low pressure line, the cartridge, and gauge dead volumes.

Note the acorn nuts on Both the gauges!! These cover the screwdriver regulator settings for each gauge. I adjusted the high pressure regulator to never let more that about 10-20PSI ever enter the low pressure regulator and then the low pressure regulator to never reach 4PSI delivered to the D2-fusor line and CO2 cartridge. This way the high pressure gauge, even with full tank pressure to even admit to its volume more than 20PSI on the high pressure gauge. Naturally, with this setting on the high pressure side, I have no idea how much gas (pressure) is left in the tank until it is truly empty.

Works for me and allows about 20 minutes of operation before I have to re-crack the tank valve to re-fill the CO2 cartridge.

I attach an old photo of my gas setup which has not changed one bit since 2000. The stuff is labeled. Again I refill the line and cartridge by artfully cracking the Tank Valve all the regulator settings are set and remain untouched from 2004 when I set them for fusor IV.

I run the fusor until I have only about 1/4 PSI registering on the 0-5PSI meter and then shut down as I know that in about 2 days the line will have leaked that tiny amount of D2 out of the entire gas system volume. Very little waste due to heavily pressurized volumes at shut down.

Richard Hull
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Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
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Matt_Gibson
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Re: NPT adapters 1/4 to 1/8

Post by Matt_Gibson »

Richard,

So maybe my regulator can still be of use? It was unused, so probably had been sitting for decades without ever having its internals worked.

The high pressure side doesn’t immediately leak down…It’ll behave as expected once I close in the valve. It takes about an hour to notice…

I left it overnight after letting the high pressure side go to 500psi. This morning, the high pressure side is near 0psi and the low pressure side is right at 500psi. I’ll see if the low pressure side holds at 500psi while I’m at work today. If it holds at 500psi, then at least I’m not losing any deuterium.

I’ll try to work it in the way that you work yours, but use the low pressure side as a “reservoir” instead of a c02 bottle as the low pressure side was able to fill up my 100mL syringe several times with just what was stored/trapped in it. I need to look at it a little more to see if I can adjust the max psi like you did too…

On the bright side, it’s definitely deuterium in there. I was activating silver to 6000cpm last night with it :-)

-Matt
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Dennis P Brown
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Re: NPT adapters 1/4 to 1/8

Post by Dennis P Brown »

As for the question of whether to use the regulator - of course it can be used. Just never forget to turn off the high pressure valve very tightly on the tank.
Matt_Gibson
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Re: NPT adapters 1/4 to 1/8

Post by Matt_Gibson »

I’ll keep that main valve tighter than a bullfrogs bum!

Looks like the gas trapped in the lower pressure side is more than enough (especially once I switch over to my cube) for a few runs anyways, so no need to keep the high pressure side filled/open.

-Matt
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