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All Springer/NP/PCP Air Gun Discussion General > PCP/CO2/HPA Air Gun Gates "The Darkside"

AIRGUNNER PUBLIC SAFETY ANNOUNCEMENT: DO NOT USE THIS PRODUCT FROM PCP TUNES

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UpNorthAirGunner:

--- Quote from: TrinityMaker on October 23, 2019, 12:12:36 PM ---He can't understand why the concern wasn't brought to him before the video was pulled and he could ask questions and have the opportunity to defend himself and his product. But I only wanted to include the fact, not the emotion in his response.

--- End quote ---

He can't understand why I deleted the video and posted the warning?  WOW.  Paul was very responsive and helpful during my testing of that regulator and as a person seemed nice to work with.  But Nice doesn't bring back people from death or being severely injured.  The person who actually relayed this info to me about what happened is a very trusted mutual friend to the person who this happened to.   The information was also relayed to Doug Noble as a technical resource to try and determine what caused the failure.  I am NOT an engineer nor the technical background to do an autopsy on what happened.  Doug and others are.  What I am though is a shooter and airgun advocate with a small but growing following. With that - it was 100% the right call to remove that video and to post the warning to all other airgunners.  If that somehow hurt PCPTunes' bottom line for sales or company reputation - that is NOT my concern nor focus.  Using gear that works and is safe and demonstrating that gear for other airgunners is my focus.  If Paul and PCP Tunes wants to bring another regullator to market I would highly suggest they send a reg to a trusted source for testing and technical / engineering review- but having that other one fail in such a dramatic and potentially deadly way 100% made me take a step back and realize I am NOT going to be someone's guinea pig.  Hope that makes sense.

TrinityMaker:
I completely understand your points (both of you guys). I never even thought about the burst disc. I don't own the Texan regulator, so I've never held it my hand to inspect it. But I think the shape of the plenum in and of itself lends the design to weakness. It blooms out to a flat bottom on one end. I don't want you guys to think that I was insinuating that anyone was lying. I was just curious about the specifics of the incident regarding whether all manufacturer suggestions and specifications were followed.

According to Paul, they have beefed up the new version. He said the bottle side of the reg AND the plenum can handle 500 BAR now. I think the only way to test it is to put it through extremes. Pressurize the reg with a 4500 psi bottle and a valve assembly on it, and let it sit for a few weeks. Put it in a safe (explosion proof container). Then let it get extremely cold for about a week. Then let it get 120 degrees for about a week. If it survives those parameters, I think it should hold up. I FULLY understand your trepidation in even considering this.

Again, sorry if you guys thought I was insinuating lying or dishonesty. I know there are 2 sides to every story, and I'm grateful for the clarity.

I know you pulled the video Chris, so I have no reference, but what were your velocities with the reg. What did you have it set for? What were you shooting (projectile weight), and did you find the shots to be consistently accurate? Admittedly, I was super excited about this regulator. Now..... NOT SO MUCH!

Pigboy1537:
Hello
    Thanks for the heads up. Something like this can can really hurt someone.

mr3D:
Seeing as how no one else has tried to speculate on the cause of the failure I’ll take a shot at it. For qualification, I do have an ME degree, but my airgun experience pales compared to some of the other members here. As a DISCLAIMER I am not legally qualified to offer engineering advice. These are just my thoughts/opinions.

I would guess that this failure is the combination of:

1. The shape of the plenum. With any pressure vessel, the design goal is to eliminate any bending stress. This is why high pressure bottles have rounded end-caps. For any high pressure vessel, visualize what would happen if the vessel was made out of a flexible material like latex. If the SHAPE of the vessel would change with applied pressure it’s a poor design. Based on the photos of this plenum, it appears that the entire back section is flat, with a sharp corner transition between the body and back cap. If we apply the “made of latex” thought experiment to this shape, it’s easy to see that the entire back cap would balloon out into a rounded shape. To compound the issue, the sharp internal transition between body and back cap would act as a stress riser which brings us into:

2. The material of the plenum. According to the website, this part is machined out of 7075 aluminum. While aluminum can be very strong, fatigue will always be an issue, and is exacerbated by geometry that acts as a stress riser. Steel parts (like valve springs), can last infinitely if not stressed beyond a certain point, but aluminum will only last a certain number of cycles, regardless of how much it is stressed. Because of this, thorough testing of the part would have to include fatigue testing for a certain number of cycles and not just a max pressure test.

If anyone is interested, I could rummage around and attempt to do some calculations to estimate how many cycles this part would last for, but my bottom line is that I would like to at least see some design changes made for this to eliminate the bending stress incurred by having the flat end-cap. However, if this has already been beefed up it could very well be safe for many more cycles than it would realistically ever be used for. This is a situation where each buyer should do their best to understand the facts and make their own decision.

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