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Whitewolf
PostPosted: Sun Jun 04, 2017 8:59 pm 
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Location: Alberta Canada
paddyfritz wrote:
If you are buying pressure fittings from China, keep in mind they have sold fakes before, and may well lie about pressure ratings.

Chinese steel does not have the same quality as what we have within North America. No different then our steel is not of the same quality as German (Euro) steel. The recipe and spec may be said of the same but Chinese steel is blended with recycled steel so much that it begs one to question. The one that places the order has the choice of quality or bargain brand steel. It's not the Chinese don't have quality it's the buyer who cheaps out upon its cost factor.
I say this because I've seen 100s of kilometres of Chinese made casing put into the ground in search of oil and gas. Just to either bulge, collapse, and burst. Costing the well operators' millions of dollars in repairs and abandonments. All because it was a good deal or Chinese money was being used to finance these projects. An industry that demands high expectations.

Just food for thought here. Manufacturing specs are only as good as they are till someone gets hurt or even killed.

My nickels worth here.

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wesb2007
PostPosted: Sun Jun 04, 2017 9:34 pm 
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Sounds like you know what you're talking about with your experience drilling. I'm sure it is a good point and if one is available somewhere else and made in Canada or US that's great. Personally I wouldn't have any trouble using it at 1500psi when it's rated for 4500psi. I'm thinking it would still be better than the brass fittings that are only rated to 1200psi. That's just me though, not encouraging anyone else to prove me wrong and getting blown up!

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wesb2007
PostPosted: Sun Jun 04, 2017 9:46 pm 
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rsterne wrote:
In general, reusable CO2 cylinders are rated at 1800 psi, which puts their hydrostatic test pressure at (5/3 x 1800) = 3000 psi, and that is the value of the burst disc fitted, to protect from filling past the test pressure.... Single use CO2 cylinders have no burst disc, so right there is a concern, extra care must be used to prevent overfilling.... By ASME rules, pressure vessels must have a 3.5:1 safety margin to burst above their working pressure, so 1800 psi x 3.5 = 6300 psi min....

Your tank seems to be well over the test and burst pressures for a reusable CO2 cylinder, as was the burst pressure on the 16 gr. CO2 I used, which was 500 bar, which is 7250 psi....

Image

It would seem to me that all CO2 cylinders are properly engineered for at least an 1800 psi working pressure.... Kim makes an interesting point about single use cylinders being derated if refilled, but I have no info on that.... Steel cylinders working below 50% of their yield point should have no concerns about fatigue, however.... so up to (4000/2) = 2000 psi for yours.... or (3600/2) = 1800 psi for my 16 gr....

Kim's points about the wall thickness where you are tapping for the Foster are correct.... If you indeed have 1/4" of thickness on the bottom, where you are installing it, I would be OK with that personally, up to the 1800 psi working pressure for CO2.... Personally, I would treat the tank as if it had a 1.8K burst disc installed (putting one in would be best).... Since those typically fail at about 1500 psi, that should provide adequate safety, providing your fill fitting, valve, etc. etc. are all installed safely, and intended to meet or exceed the test pressure of 4000 psi....

Bear in mind, I'm NOT an Engineer, and that Kim is better qualified to give advice on things like this.... Personally I would have no problem using it for CO2, or with HPA up to the burst point of a 1.8K disc (1400-1500 psi).... but that's just me.... and subject to all work being properly done....

Bob

Thanks for clarifying and sharing, and my apologies for getting things wrong with the burst pressure, I was way off!

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paddyfritz
PostPosted: Sun Jun 04, 2017 10:28 pm 
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wesb2007 wrote:
Sounds like you know what you're talking about with your experience drilling. I'm sure it is a good point and if one is available somewhere else and made in Canada or US that's great. Personally I wouldn't have any trouble using it at 1500psi when it's rated for 4500psi. I'm thinking it would still be better than the brass fittings that are only rated to 1200psi. That's just me though, not encouraging anyone else to prove me wrong and getting blown up!

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The ratings the Chinese put on them dont really mean anything. They have plated brass before to make it look like steel and stamped it 4500. If its cheap, assume its made for paintball use.

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wesb2007
PostPosted: Sun Jun 04, 2017 11:20 pm 
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You're right, probably not worth the risk. Actually probably just better off buying the 13ci hpa tank for the qb79, though a smaller hpa tank would sure be nice! I see there is some or was some 7,8,9 and 10 ci tanks available but they are even more expensive than the 13ci and the ones I saw don't come with a regulator, so you'd have to buy that as well plus the drop down adapter for the qb79. Adds up to a lot of money. Better than getting shrapnel flying all over though!

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nvreloader
PostPosted: Mon Jun 05, 2017 4:58 pm 
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Location: Western NV
Thanks guys

Learning more all the time,
I just wish I could find some air tanks smaller than 9 oz types,
that were smaller in diameter, right around 1.850" and about 6" long,
and for HPA, would be great.

Tia,
Don

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QB-79, 22 cal
Airforce Condor 22 cal - pending
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rsterne
PostPosted: Mon Jun 05, 2017 6:53 pm 
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Google 9 CI or 10 CI HPA tanks.... Bottle only $30....

http://milsigdirect.com/shop/new/10-ci- ... ir-bottle/

Bob

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nvreloader
PostPosted: Mon Jun 05, 2017 7:19 pm 
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Bob

Thanks for the info, looks to be just what I wanted,
even thou they don't list the actual sizes of these bottles, length/diameter etc,
I am hoping that this bottle will be close to the smaller bottle I have in my OP.

I see they offer a reg to go with with this bottle,
could this reg be stepped up to the 700-800 fps/psi for a 22 cal, QB-79?

I want to start off hand pumping, (Hill type, 4500 psi),
until I get the funds built back up so I can get a good home compressor etc.

I will order the QB-79 in the am, I forgot about the time difference to the East coat. :roll:

I have over 55+ of the 88/90grm co2 bottles that I can use, until I have every thing set up,
for both summer/winter shooting etc.

Got a suggestions on which way to go, as far as this tank/reg etc?

I am hoping that there is some type of shutoff for the co2 bottles,
as I am sure I will end up having to change all the seals/o rings etc.

I have been slowly reading all the posts here (on pg # 75) to find out some info, on the QB-79 etc
as this sites search dog just doesn't want to hunt for me, I get no info etc.

Tia,
Don

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QB-79, 22 cal
Airforce Condor 22 cal - pending
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rsterne
PostPosted: Mon Jun 05, 2017 7:58 pm 
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I assume the 10 CI tank is the same diameter as the 13 CI (just under 2"), and they fit under the barrel on a QB79.... An email to them should provide the answer.... I usually use Ninja regs, but if you are only looking for 850 psi CO2 pressures, any will work, but make sure they have TWO burst discs, and that the one on the output side is a 1.8K....

Bob

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Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
Airsonal; Too many! Springers, Pumpers, CO2, but I love my PCPs and developing them!
Proud Member of the 2000+fps Club!
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wesb2007
PostPosted: Mon Jun 05, 2017 8:44 pm 
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That's a great price on that 10ci! Did anyone contact them to see if they ship to Canada? Their checkout only has the US.
I hear you on the search, doesn't work for me either! I type my search into google along with Canadian airgun forum and get better results that way.

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wesb2007
PostPosted: Mon Jun 05, 2017 8:52 pm 
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Here is my qb78 with the two 90g tanks. As I said it's pretty heavy this way! Just shot a 45 shot string from 1500psi to 1000psi. Started at 767fps, went slowly up to 892 fps at 1300psi and down again til I stopped at 1000psi, 809fps.30 shots in a 50fps spread. A lot of extra steel to lug around though, and my scope is overkill as well lol!
Anyway since you were looking at the 90g tanks, thought I'd share. Image

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wesb2007
PostPosted: Mon Jun 05, 2017 9:01 pm 
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Oops actually it was a 60 fps spread. Shooting a little faster than I planned too, will retune to top out at around 800 and then can drop the initial psi as well for extra safety and still hopefully raise my shot count.
The 10 ci would be a much better option for the qb79 though! Should work great!

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nvreloader
PostPosted: Tue Jun 06, 2017 10:38 am 
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Location: Western NV
Bob

Sorry for all the questions,
here is the reg that they have, they don't specify the model number,
but they state that it can be adjusted to several different psi,
it has 2 burst disc and the one I can see is 1.8k.

I have sent then an email for the spec's along with the dimensions of the tank etc,
as I am looking for some 7,8,9 and 10 ci smaller tanks for my use in a hunting setup.

http://milsigdirect.com/shop/accessorie ... regulator/


Wesb2007
What kind of manifold are you using on that QB-79,
I would like to see a close up photo's of it if possible,

That set up would be fun in the pop gut (squirrel) fields from a shoot table etc,
I want to run somewhere around 800-900 fps with the medium weight pellets etc.

Tia,
Don

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QB-79, 22 cal
Airforce Condor 22 cal - pending
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nvreloader
PostPosted: Tue Jun 06, 2017 1:05 pm 
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Posts: 48
Location: Western NV
Well guys

I am the proud? new owner of a QB-79, 22 cal AR,
with the drop down adapter, so I can use all the different co2 air supply's available.

Should be here by early next week, I guess, I have slid off the edge,
and :drinkers: the Kool Aid of the dark side now.

On that note, being new to an AR, what should I do first,
1. Shoot it for several co2 bottles, learning it's quirks etc,
2. Dismantle/clean it inside and out, deburring etc, then shoot it etc.
3. ???? on pellets weights, start in the middle weight range, for the best accuracy etc,
4. I will be setting this AR up for hunting small game and pest control for starlings/HS etc,
out to 50 yds max.

I have a 4x14x50 Mueller scope and rings waiting and a Magnetic chrono for use with it.

Thoughts, suggestions......

Tia,
Don

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"Speeds fine, but accuracy is final"

QB-79, 22 cal
Airforce Condor 22 cal - pending
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wesb2007
PostPosted: Tue Jun 06, 2017 6:37 pm 
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Congratulations! Those are nice looking guns! I like the AR stock. If you are going to get 800-900fps, then you'll definitely have to take it apart, and change the transfer port seal for something bigger, like a crosman 1322 transfer port seal. You can get them from canadashootingsupply.ca, ask for the free shipping via letter mail option, otherwise you'll pay an arm and leg for shipping. At the same time buy their QB barrel orings pack, because when you take your barrel off you'll probably have shredded orings. Debur inside there where the barrel grub screw hole is to prevent reshredding the new orings when you put the barrel back on. While you have the barrel and breech off then is a good time to take valve and hammer etc out and polish/Debur, but also you'll need a long screw driver to stick down the tube from the front to partly unscrew the front of the valve to take the pressure off the oring on the valve. Make sure and take out the valve retention screw before this then you should be able to easily push the valve out from the back pushing it out the front. You'll have to modify the valve for more airflow. I think Bob might have a great post on all this, hopefully he'll give you a link.

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