hybrid fill bottle imporvisation

[r2kordmaa]

Hi

hybrid fill bottles are not exactly easy to aquire these days for reasonable price, solenoids cost quite a lot too, so heres my idea:

would a co2 extinguisher(painted blue according to eu requierements) fitted with a lower pressure pneumatic cylinder for valve acutation, do the job or not

will performance shops fill it?

pitfalls, risks, dangers?

 

[WillMarchant]

I suggest that the place to start is with your local flying clubs to see if anyone already has safe GSE.

My opinion is that trying to cut corners on GSE is a bad idea. If your rocket blows up then you should be at a safe distance because of the safety code. If your GSE fails it will probably do so when you're turning it on and you are up close and personal. I've sat through enough of the NASA high pressure gas safety videos to know that I don't want to be involved in that sort of incident. Your mileage may vary...

 

[r2kordmaa]

sorry there are no local clubs prolly within 1000km radius, this is eastern europe Estonia im talking about. co2 bottles are made according to eu safety standards, i dont really plan to modify valve or tubing at all, just add a low pressure cylinder to the handle to acutate the valve remotely from a safe distance.

co2 and n2o bottles are meant to operate at the same pressure so there should be no problems like that

but im a bit conserved about the oxidizing properties of n2o, perhaps co2 extinguisher seals are not suitable for that, if anyone has rebuilt a co2 extinguisher to hybrid fill bottle please let me know your results

other possible problem is that fill valve might not match so the performance shops may refuse or be unable to fill it

 

[WillMarchant]

Ah, sorry to hear about the lack of local clubs.

Yes, I agree with your concern about seal compatibility. https://pratthobbies.com/proddetail.asp?prod=T-20&cat=9 advertises that his tanks are "oxygen cleaned."

Have you tried talking to the local speed shops to see if they have used hybrid tanks for sale?

And they might have used "remote opener" systems which could substitute for a solenoid. That's basically a motor attached to the tank valve.

 

[r2kordmaa]

speed shops ask outrageous prices over here.

also to note i have talked about pneumatic piston operated 'remote opener' from the start, have plenty pneumatic equipment at work to make it in minutes

i have even made portable low pressure pneumatic systems before, thats an non issue

also im wondering if n2o in itself is oxydizing, in rocket motor its decomposed by heat and then the oxygen does the oxidizing. if n2o at room temperature is not oxidizing then seals should be no consern at all.

 

[jderimig]

speed shops ask outrageous prices over here.

also to note i have talked about pneumatic piston operated 'remote opener' from the start, have plenty pneumatic equipment at work to make it in minutes

i have even made portable low pressure pneumatic systems before, thats an non issue

also im wondering if n2o in itself is oxydizing, in rocket motor its decomposed by heat and then the oxygen does the oxidizing. if n2o at room temperature is not oxidizing then seals should be no consern at all.

N2O is MUCH safer than O2, but you should be able to find a gas supplier who will oxygen clean your cylinder for you.

I would be cautious of using "low pressure' valves however. You need at least 1000 psi working pressure on those valves with 1500 being even better. You will also need be able to fit a CGA326 or 660 valve on that cylinder or no one will fill it for you. That may be the biggest problem. Cheap consumer CO2 bottles may not designed for replaceable valves.

 

[r2kordmaa]

oh you misunderstood me, i want to attach a low pressure pneumatic actuator to the excisting fire extinguisher handle and power it with regular low pressure compressed air
something like this

have loads of pistons all over the place, with this i can open and close the high pressure bottle valve remotely

[edit]

it seems to have a fill valve but what type... thats the question,
thank you for telling me what type i need,
but it would be nice to have any info if most fire extinguishers have this type of valve or not

[edit]
seems like for co2 connections valve type CGA 320 is used and CGA 326 is used for n2o so thank you i got my answer,
i would have to switch the bottle valve if i wanted to use it as nitrous bottle

 

[bobkrech]

Yes it will work, but you may have difficulty having it filled. CO2 and N2O have the same vapor pressure curves. Also high pressure CO2 is a good degreaser so the cylinder should be clean. Just remember that you can not use grease on an oxidizer cylinder.

You also should have a flow limiting orifice or metering valve downstream of the pneumatic actuated on-off valve so you won't dump the cylinder after firing. You also need a remote dump valve just in case you can't fire the motor.

Bob

 

[r2kordmaa]

thanks for your answer bobkrech, co2 being a good degreaser is a news to me but rest of it i am aware of, i think i will skip the dump valve now tho, i will start with smallest hybrids anyway i can wait for it to vent off. also i see little need for flow limiting, wouldnt it make more sense to just close the valve before ignition?

 

[bobkrech]

thanks for your answer bobkrech, co2 being a good degreaser is a news to me but rest of it i am aware of, i think i will skip the dump valve now tho, i will start with smallest hybrids anyway i can wait for it to vent off. also i see little need for flow limiting, wouldnt it make more sense to just close the valve before ignition?

No. You do not want to close the valve before ignition.

The flight tank pressure will drop and the nitrous will cool, and you will not get the expected performance out of the motor.

You also really want the dump valve.

Also paint the tank another color, and remove wording about a fire extinguisher. Label the tank as nitrous oxide, oxidizer, keep away from fire.

You never want to spray nitrous on a fire by accident. The results will be a much bigger fire!

BTW - Liquid CO2 is a good degreaser above the critical temperature. Gaseous CO2 has no effect.

Bob

 

[r2kordmaa]

i know about the n2o coloring, blue right? according to some eu directive

for now most important is to get a tank that actually mates with the fill equipment at the performance shop
i can move forward once i have that

n2o at room temperature is not flammable, and does not decompose under about 600C ? still fire safety is always a good idea and spilling boiling n2o from a hose under some 50bar of pressure is not that fun anyway

 

[bobkrech]

I have no idea what the EU color standards are for gas cylinders.

The real issue is that you do not have the correct valve assembly on your tank, so it is possible, and even likely, that the hot rod shops will refuse to fill the cylinder.

For safety purposes, the decomposition temperature is not important. Nitrous oxide is an oxidizer, not a flammable substance. It supports and accelerates the rate of combustion compared with air and certain chemicals, valve friction or opening shock can cause it to decompose, and once the decomposition starts, you won't stop it, and any flammable materials in contact with it can ignite. It should be treated with respect and caution.

Bob

 

[andytherocketeer]

I have no idea what the EU color standards are for gas cylinders.

I sometimes wonder if the EU does too! Especially fire extinguishers. Used to have a handy colour coded system for each type, so they changed the law to make them all red.
AFAIK N2O tanks should be blue.

 

[r2kordmaa]

seems like bottle improvisation will be unnessecery Linge gas will sell me 16lb of nitrous for 200$ and rent a bottle to go with it i'll take it for starters.

 

[Gillard]

AFAIK N2O tanks should be blue.

My tank was blue.