Lightweight cylinder HW 100 carbine recommendation

[Goatofmendez]

So what is the maximum MPa for 6082T6 Aluminium?

Still can't understand why the tube went pop at 150bar though. Also is it legal to send compressed air cylinders in the post? What postal method do you use?

thanks

[Bladerunner too]

So what is the maximum MPa for 6082T6 Aluminium?

Still can't understand why the tube went pop at 150bar though. Also is it legal to send compressed air cylinders in the post? What postal method do you use?

thanks

Are you still confused why the cylinder went pop at the 150 bar? Well maybe it was a tad over 150 bar.and/or been fitted wrong, or maybe i am just suspicious of certain claims.

[mikec4]

The shooter who had the unfortunate experience with the "splitting" air cylinder is a close friend of mine. He is not a beginner with little knowledge of correctly charging air cylinders, but a veteran shooter who just fancied a lighter HW100.
I am sure we can all imagine what it must feel like to have that amount of pressure suddenly vent to atmosphere while holding it in your hand for a charge. In addition to an underpants change, he suffered numbing of his fingers and in my opinion was very lucky not to lose them. At least it split cleanly. I also hate to think of the outcome should the cylinder have turned into shrapnel rather than the clean split. I couldn't believe it when shown the offending cylinder.
Hopefully this item was a rogue. There again, it might not be.
Personally, this will mean, for me anyway, that I will be keeping with the original manufacturers specification for a guns air cylinder. Steel might be heavy, but I haven't heard of one suffering catastrophic damage like this one. I can remember talking to Shaun at I.S.P about the amount of pressure one of his titanium air cylinders was able to withstand, 400 bar plus on testing and still retaining integrity. Obviously then, a correctly manufactured titanium cylinder has the ability to take our normal 200 bar ish pressures without turning into a bomb.
I think that the problem has everything to do with the manufacturing process, obviously. I am not a structural engineer, but from this point I would be very careful about purchasing any none standard pressure vessel. This is unfortunate for those companies who do manufacture high quality and trustworthy cylinders, but, for me, I would never now take any risk.

Finally, this is a serious reminder to all of us who may have become blase about the continual use of highly pressurised air. We all know that our air filling and pressure vessels need to be treated with care and that the slow filling of cylinders is best practice.

Andy

A club member and friend bought this off that there internet web auction site brand new for his HW100. On the first fill, after fitting his spare ends, at 150 BAR it split from top to bottom. He was lucky not to lose his hand. After he had come back from the toilet he rang the supplier. From what I gather they tried to tell him, an ex engineer, that he had over filled it. He got a refund. Motto: Buyer beware. Cheap isn't always best.

Are you still confused why the cylinder went pop at the 150 bar? Well maybe it was a tad over 150 bar.and/or been fitted wrong, or maybe i am just suspicious of certain claims.

So the three of us who saw this know that the member it happened to is a skilled engineer of many years standing, and you are suspicious of the posts we have made?? The wall thickness at the point of fracture is less than 3mm.
Come and have a look if you don't believe us.

Merry Christmas.....

[krisko]

Wondering if the biopod screw was not screwed in way too deep into the 8 hitting the cylinder, are there any other marks?

[mikec4]

Wondering if the biopod screw was not screwed in way too deep into the 8 hitting the cylinder, are there any other marks?

Never fitted to the rifle. Doesn't use a bipod anyway....

No marks at all on the cylinder; no date of manufacture, nothing ....pristine glossy black surface.

[I. J.]

So the three of us who saw this know that the member it happened to is a skilled engineer of many years standing, and you are suspicious of the posts we have made?? The wall thickness at the point of fracture is less than 3mm.
Come and have a look if you don't believe us.

Merry Christmas.....

I can confirm this club member spent most of his working life in engineering from plant machinery to car mechanic. Ive entrusted him to work on my own HW100 with 100% satisfaction and Ive seen him work on several other club members guns successfully.

Wondering if the biopod screw was not screwed in way too deep into the 8 hitting the cylinder, are there any other marks?

He didn't even get chance to fit it to his rifle.

ATB
Ian

[Amac]

Take it from me that this cylinder had not been abused in any way. The owner was literally just giving it it's initial charge when the incident occured. He is not some novice who doesn't have a clue how to use highly compressed air, and the fact that this is being implied is quite frankly offensive.

[Goatofmendez]

So the three of us who saw this know that the member it happened to is a skilled engineer of many years standing, and you are suspicious of the posts we have made?? The wall thickness at the point of fracture is less than 3mm.
Come and have a look if you don't believe us.

Merry Christmas.....

Exactly, the claims simply do not make sense. E.g. the ends are designed as standard HW100 ends and as such the part of the cylinder internally that the o-ring sits on is 30mm. The OD of the tube is 37mm. So 37mm - 30mm = 7mm. Divide that by 2 for the wall thickness = 3.5mm MAXIMUM. So the wall thickness cannot be 4.3mm at it's thinnest part.

[NickG]

Exactly, the claims simply do not make sense. E.g. the ends are designed as standard HW100 ends and as such the part of the cylinder internally that the o-ring sits on is 30mm. The OD of the tube is 37mm. So 37mm - 30mm = 7mm. Divide that by 2 for the wall thickness = 3.5mm MAXIMUM. So the wall thickness cannot be 4.3mm at it's thinnest part.

forget the major diameter of the internal thread is even larger , if its a 1mm pitch (a guess as I haven't measured one but would assume a fine thread ) the thread depth will be in the region of 0.8mm so that makes a wall thickness of 2.7mm not a lot when you think about it .

[Willsinker]

forget the major diameter of the internal thread is even larger , if its a 1mm pitch (a guess as I haven't measured one but would assume a fine thread ) the thread depth will be in the region of 0.8mm so that makes a wall thickness of 2.7mm not a lot when you think about it .

Fenton’s attitude to this issue is quite disturbing. It’s reminiscent of a green grocer reacting to a complaint of blighted Maris Pipers.
Taking pride in one catastrophic failure out of only 100 units sold (actually 101 if Luftgewehr’s recently inspired purchase is included), betrays a somewhat bewildering grasp of the situation. I doubt Rolls Royce would be so sanguine if one in every 101 jet engines consumed themselves so dramatically. Exactly how many of these potential pipe bombs are yet to explode remains to be seen. Should there be another, let’s hope the photographs don’t include severed digits or someone’s gonads imitating a testicle smoothie!

Until the root cause of this failure is determined all devices using this cylinder should be treated with extreme caution. However, following the complaint, no attempt was made to retrieve the failed part for analysis. Instead, speculation appears to be the preferred method of investigation; resulting in a meaningless paper shuffling exercise, amounting to nothing more than facile window dressing, in a feeble attempt to ‘mitigate risk’ and protect the ‘airgun community’.

[I. J.]

As stated in my earlier post (# 32) the owner of this failed HW100 cylinder is not a member of this or any other airgun forum. He has passed me the following message:

'I will release the offending tube to someone who will carry out an inspection and analysis of the tube. This must
not be anyone who has any affiliation to the supplier. '.

ATB
Ian

[jepho]

So what is the maximum MPa for 6082T6 Aluminium?

Still can't understand why the tube went pop at 150bar though. Also is it legal to send compressed air cylinders in the post? What postal method do you use?

thanks

This thread was a great public service announcement to people who are (like me) considering the various options for cylinder and regulator upgrades to my HW100.

Any failure of a pressure component at only 75% of its nominally rated use pressure; must be completely unacceptable. If the item has failed at 25% less than its rated use parameters, it implies both poor construction and inadequate testing. Any engineering environment would hang its company head in shame if this sort of failure became known outside of the company.

Removing all of the personalities involved (I don't know any of them and it just serves to cloud the issues) I would defy anyone to justify producing vital components that fail with much less than normal use. Where components are crucial to the operation of the equipment and failure is dangerous, the components must be over-engineered and fitted with a degree of redundancy to prevent harm to individuals using the equipment. Anything less displays a cavalier disregard for the continuing good health of the user.

It is incumbent upon the manufacturer to instantly cease all sales of the 'upgrade' until the issue of cylinder collapse for reasons unknown has been independently examined, analysed and fixed. Anything less is to ignore the potential harm which may be caused to purchasers by another random and unexplained cylinder failure. The glib assurances from the supplier are not convincing. They make me want to keep well away from the company's products for all time. I will not be rushing out to purchase a cylinder; as a sign that I believe in the open and honest approach of the company; as supposedly demonstrated in this thread.

The best case I can ascribe to this event is that the company are absent-mindedly foolhardy. The worst case does even not bear thinking about.

It has been very worthwhile for me to join the forum. It has permitted me to follow this dangerous and distressing and event and to read the excellent responses to the manufacturer; who to all intents and purposes appears to be oblivious to the potential for future harm being caused by the company's similar products on offer. My new membership of AirgunBBS has saved me money and possibly my hands, eyes or worse. Thank you all members who contributed to a really informative thread.