by B.B. Pelletier
Today’s post is the thousandth since we began in March 2005. How fitting that it should come on Christmas Eve. Regardless of your religious views, we all owe Pyramyd AIR thanks for their gift of this blog that has lasted so long. Let’s hope we’ll still be enjoying it after another thousand reports!
Although Abe asked for this report, I’ve heard from a lot of other readers who had questions and comments about air tanks. I’ll try to address them all today.
Lloyd wants me to tell you that you should buy the largest scuba tank you can afford. He also says to tell the dive shop operator to please fill the tank to the max, because divers are less concerned with pressure than we are. His most important message, though, is to get to know the people at your dive shop. I couldn’t agree more. I’ve seen airgunners ruin their entire PCP arrangement by simply alienating the dive shop personnel. And I’ve gotten many concessions and good treatment because I acted as though the dive shop was doing me a favor–WHICH IT IS. A little civility goes a long way when dealing with an owner/operator, like the guy who runs the dive shop.
Lloyd also asks if dive shops are the only place to get a 4500 psi fill. Well, I think they are the WORST place! I go to a paintball shop, because my dive shop fills me to only 4,000 psi or so. That’s all his air system can produce. Sometimes, you can get a fill from the local fire station. It helps if the firefighters are also airgunners or maybe you take them a couple dozen donuts when you go there. Like I said, some guys can do it and others can’t. Ask yourself, “What would Wayne do?” when you go, and you’ll probably get what you want.
Jony wants me to remind you that a smaller tank at higher pressure is often better than a large tank at lower pressure. The proof of that is the fact that a 2,200 psi tank won’t even give you one fill of your AirForce Talon SS, despite being just as physically large as an 80 cubic foot aluminum tank that gets pressurized to 3,000 psi. In this game, pressure is king, and we either want tanks at higher pressure or guns that shoot at lower pressure. Having both is the best of all.
Pony tanks
A pony tank is a small air tank that divers and rescue workers use for convenience or for emergencies. We used them in the Army when fording rivers in our M60A1 battle tanks, because some of the crew members in the tank were 10 feet under water when the tank was driving across the river bed. If the air snorkel tube collapsed at those times, the driver could drown before he could get out of the tank. So, he used a pony air tank for a five-minute emergency air supply.
Big bore hunters carry carbon-fiber pony tanks to top off their rifles during a hunt. A small tank that fits in a backpack can refill even a large big bore rifle 2-3 times for a total of 6 additional shots. Any big-bore hunter will tell you that six shots is probably more than a day’s supply for big-game.
When I competed in field target, I carried a 13-cubic foot pony tank to top off my Daystate Harrier. That rifle, which filled to 2,650 psi, got three refills from that little 3,000 psi pony tank. Since each fill was good for 24 shots, that was enough for almost 100 shots if you factor in the initial fill. A match typically has only 60 shots, so I was covered.
The Benjamin air tank is an example of a pony tank. Because it works on the Benjamin Discovery rifle which operates at 2,000 psi, it still gives plenty of fills.
Pony tanks have their place in PCP guns, but you don’t want to buy one as your principal source of air.
Mr. B. says a day in the woods requires more shots than a Talon SS air tank can offer (maybe 35-45 shots at full power, depending on the range). Well, Mr. B., that Talon SS tank is actually a pony tank! Why not buy an extra AirForce standard tank? When your first one runs dry, just screw on a new one? That’s how AirForce designed the gun to begin with.
Filling a gun from a tank
Abe asks about the proper way to fill a gun from a scuba tank, and I’ve had several other people ask the same thing. Here’s a report I did on that subject. The first step is to connect the scuba tank to the gun. For this you need a fill adapter. One end connects to the scuba tank, the other connects to the gun. Both have to fit what they connect to, so you have to determine what it takes to do that. Scuba tanks and carbon fiber tanks have all kinds of valves. The most common scuba tank valve in the U.S. in the K-valve, but a DIN valve will sometimes be encountered. When the rated tank pressure goes above 3,000 psi, the DIN valve becomes more common. Your job is to determine what kind of valve your air tank has.
The K-valve is flat with an o-ring to seal it. This type needs a clamp that fits around the back of the valve to hold it.
A DIN valve has a hole with threads to accept any devices. This is the deeper 300-bar DIN hole, though both have the same diameter and threads.
A refill clamp fits around the K-valve.
Abe also asked about the scuba tank inspection process. That’s not a part of this report, but I covered it here and also here.
Buying used
Sooner or later, it’ll dawn on you that a used scuba tank would be cheaper than a new one. But what you don’t know is that there’s a very good reason for that. A scuba tank must pass a hydrostatic pressure test every five years. When they fail or when they get near the end of their useful life, they aren’t worth buying. We had a reader who bought a used tank for $50, then had to spend $135 getting it back in shape. While that was a little extreme (he needed a new K-valve), a hydro and the other tests you need could easily cost $60. And you could wind up with a tank that fails its hydro, leaving you with nothing, because the testing facility will drill a hole in your tank to remove it from the market.
The best way to buy used is to buy from a dive shop you do business with. If there’s a problem, they’ll take care of you.
Vince,(from yesterday)
I think the Umarex Quest is a Perfecta 55, I haven’t checked in a while. The only difference is a monte carole cheek rest. My quest (storm XT) had its’ stock shaped and chainlink checkered, I also put in other small things like a thumb rest, mendoza peep sight and beeman ported muzzle brake. It shoots around an inch at 20yards,and slightly better with a scope. Oh, and breech seal shim works wonders.
Shadow express dude
B.B.What is your opinion on the proper number of shots or time spent practicing to get your best potential marksmanship.I believe that quality not quantity is key and stop when I lose concentration,be it 20 or 100shots?Also awhile back ther was a discussion about the best deer rifles.I’d love to get a Winchester 94,but prices are thru the roof and the top ejection causes scope mounting problems.What do you or readers think of the Marlin 336 in 30-30?Have a merry and safe Christmas.Thanks.JERSEY BOY
Thank you for doing what you do. Merry Christmas Tom and a Happy New Year! From SavageSam
Jersey Boy,
I agree with you completely on the number of shots for training. As you train, that number will increase with experience.
I can buy a used 94 for $350. But as you point out, the Marlin is the stronger gun and better-suited to scopes.
B.B.
SavageSam,
Thank you and Merry Christmas to you!
B.B.
Good morning B.B., Merry Christmas to One and All! Number 1000–thank you B.B. for your patient sharing of your vast knowledge about our beloved sport.
Yes sir to another tank from AirForce for woods walking and plinking with my Talon SS. Now, if I can only get Van to make me a fitting to use the AirForce tank to charge my Discovery…..:)
Please say a prayer for all of the men and women serving in our military.
Hey Tom I think I know the answer to this question but using the old “The only dumb question is the one you didn’t ask” Is is safe or OK to fill a scuba tank with Nitrogen? Can it be done? From SavageSam
RE: Scuba tank with nitrogen
Being a chemist, air is 80% nitrogen anyway. so It wouldn’t hurt the tank. You can’t breath pure nitrogen of course.
Pragmatically though I would wonder how it would be done. A drive shop isn’t going to have pure nitrogen since it would be a deadly fill. A vendor who sells HPA won’t have the proper fittings to fill a scuba tank for the same reason.
It seems to me that such a service would depend on you getting a special favor from someone….
Herb
Herb, If you did fill a scuba tank with Nitrogen, would it forever ruin the tank for dive use? From SavageSam
I think SavageSam is thinking about a welding supply house. It wouldn’t hurt the tank for future diving use, but you’d need to empty the nitrogen from tank and that can induce moisture, so then you’d have to deal with that…
Have great holiday everybody!
derrick
not being a pro in either the tire or scuba worlds, but … what about the tire shops that fill car tires with nitrogen for an additional $5 or so, as a source, once you do business with them and schmooze them up … the ads I’ve seen say N is better for retaining correct pressure since it’s molecules are larger than breathing air, hence they don’t leak thru the rubber and around the bead as much … but would that alter calibration of PCP airgun valves ?
And as for N ruining a scuba tank for breathing air after a N fill, why not just exhaust all the N, partially fill and purge with breathing air a time or 3, then go to full fill of breathing air for a dive ?
B.B.,
I’d like to read more of your writings regarding high pressure SBCA tanks (4500psi) in general including routine maintenance if you know any. Thanks.
Alan
SavageSam,
From a technical point of view, nitrogen can be put into a scuba tank without a problem,.
But it never will.
Because [people cannot survive on nitrogen, and scuba tanks are for breathing. So nobody will fill a scuba tank with nitrogen and there is no fill apparatus to do it.
If I am wrong, ler the experts chime in and correct me.
B.B.
Anal,
There isn’t any routine maintenance for a carbon fiber tank that I know of. But there are some handling cautions.
I don’t know if there is a whole blog’s worth but I will think about it.
Other readers, please chime in.
B.B.
BB,
I consider this blog as your Christmas gift to me. Thank you sir and Merry Christmas to you and yours.
I shoot a lot during practice and training sessions. My future seems to need a pump for topping off but I am concerned about moisture getting into my rifle’s reservoir.
Abe
BB, many thanks for your wisdom on all things airgun,your sharing spirit,and your gentlemanly example…MERRY Christmas! p.s.would you expect silicone grease for plumbers to be ok for HPA?it lists no other ingredient,and with potable water I would guess they would have to mention any other ingredient…? FrankB
Abe,
I won’t lie to you about pumps. They do put more moisture into the gun than a scuba tank, but if you operate them correctly, which means bleeding the right way, I don’t think they are a problem.
B.B.
Frank,
The key in what you ask may be the word potable. I would think they have to use food-grade silicone for that, and that is what divers’ silicone is.
I give no guarantees, but I would do it.
B.B.
OT…good god, there goes the diet.
Minutes ago they (the powers that be) brought in the little festive lunch for the staff.
Not 3 feet from where I sit is a large table filled with sandwich meats, shrimp, spinach dips, various cheeses, grapes, breads and crackers.
Plus rum and eggnog and 4 kinds of beer.
Help me god/ess!!
Merry Christmas to all.
CowBoyStar Dad
BB,if you see no flaw in my thinking,I need no guarantee….My 2 month old condor deluxe package throws the occasional off power shot.i think the hammerweight is in need of lube.the diveshop was out of silicone.BTW/ he filled my 80 CF aluminum tank to 3600 psi…probably cooled off to 3450ish…nice guy!so far in .22 ,5 shots with eujins at 133 yards,all on 12″ square, but 2 through the same hole[elongated].can’t wait to further explore it’s accuracy.[to be clear,the other three were not even close…] FrankB
CowboyStarDad,
You must be new. First trip, take a little bit of everything, so you can find out what’s worth bulking up on in subsequent trips. The eggnog and 4 beers is a tough decision, as they don’t go together too well. No one but you can make that choice…:).
We want a Red Ryder Report reception report sometime after you’re finished popping the crackers tomorrow.
Abe,
I use double moisture filters. One at the hose pump connection and another at the probe hose connection.
No idea if they work, but they make me feel good.
Volvo
BB and Others:
Season’s Greetings and I wish you all a healthy, prosperous, superb 2009!
My Beeman R7 came with a “bolt-on” front sight, a flat-topped, shrouded blade. I think the blade is too wide because it doesn’t allow me to aim as accurately as I want to. I have seen other front sight posts for air rifles that come to a point. Also, the front sight shroud on my gun has a reeded collar on the shooter side that looks as if it should screw off, but I couldn’t unscrew it with normal force and am afraid of breaking it if I use too much. If it unscrews, will it allow me to use inserts?
I went to the Beeman website to see if they have information on the front sights, but couldn’t find any. What I want to do is get and install a pointed front post sight or else get one that will accept inserts and will work on the R7. Any ideas?
Regarding the discussions that note the Discovery’s “loose” barrel, I tried to get a closer look at how the barrel band is installed by going online and enlarging pictures. No success. Isn’t there some way that the band could merely be loosened and moved closer to the end of the barrel and then be retightened?
–Witt
Witt,
That R- 7 sight should unscrew. They use to include an assortment of various inserts with the rifle.
As far as the Discovery, a couple guys offer after market barrel bands so you can add a second. Or you can just order an extra from Crosman.
Volvo
HAPPY HOLIDAYS EVERYONE!!!!!
Have a fun and safe time.
AJ
Frank,
You never LUBRICATE anything with silicone. It’s for SEALING, only.
The hammer weight in your Condor has a baked-on Teflon finish. It’s lubed for life. Oil will slow it down.
If your Condor throws an occasional off-power shot you need to talk to AortForce. They will want to know velocities, or how you know the shot is off-power.
B.B.
Witt,
The R7 front sight sold today doesn’t take inserts. The knurling is decorative. But I believe an R1 front sight can be fitted and it does take inserts.
Call Pyramyd AIR and ask a tech.
B.B.
Merry Christmas everyone!
FrankB,
I bought silicone grease in a small, white, plastic tub (1/2 oz) at Ace Hardware. Ace provides the following information.
o For rubber and synthetic “O” rings
o No petroleum additives
o Waterproof, non-staining, non-toxic, non-flammable
o 450 deg. F max
o 90% pure
It is probably fine for PCPs, but I decided to buy diver’s silicone grease anyway. I use the Ace silicone for CO2 stuff.
.22 multi-shot
BB,
I read the tail end of the previous tank blog’s comments and Jay Hodge brought up welding shops as a source for gas. Now those we have here:). I’m assuming either oxygen or acetylene would be a BAD idea:), but it might be a good place to look for air. Just pointing it out in case someone missed it.
Merry Christmas to all, or whatever your personal/local variant is.
thank you all for your input.BB,what I meant by off-power is that it actually stuck a pellet once during shooting.other instances involved shots thatwere clearly less than half power.dramatically different report and impact sound on 55 gal drum at 30 yds.barely dimpled the metal.not in valve lock either.Thank you for clarifying about the hammer lube.I just assumed the procedure in the dvd somehow affected the hammer…there is my problem,assuming!these 4 or so shots were not during valve lock,and were not consecutive.Condor has about 650 shots through it…these misfires were sepparated by 100 or more shots and all on different days.I’m hoping its nothing requiring attention.I’ve used jb paste per your instructions.I now shoot CPs on CO2 only.Crowmags or heavier w/ hiflo tank only. FRANKB
BG_Farmer,
Yes, other industrial gasses are a problem for the new PCP user. I have had people argue that acetylene might be a good gas to experiment with, and Pyramyd AIR has a Career 707 that an owner – a medical technician – melted, when he tried to operate it on oxygen.
B.B.
Frank,
Thank you for your detailed report. I think I know exactly what went wrong. The pellet wasn’t seated in the barrel and the skirt hung up on the breech. The Condor demands a deep-seated pellet.
I can make a Condor valve stick open and dump all the air in the tank, simply by failing to seat the pellet deeply enough. This is a known effect of the manual seating of pellets in the barrel.
All you have to remember is to push the pellet in deeply with your finger. Never just lay it in the breech.
B.B.
What would be the desire to use nitrogen over plain air? Air is predominantly nitrogen anyway. I can’t foresee any measureable difference. It can’t be liquified at normal temps or pressures, so it won’t provide the high shot-count or steady pressures of CO2. In many applications, N2 is preferred for “control air”, “process air”, or “blanket air”,(to keep oxygen away, from food, for example). It is dry and non-reactive, (regular air is a mixture of O2, N2, H20, xenon, argon, and a host of other gasses), and more readily available in “purified” forms. There is no such thing as “pure” air.
Service stations will often use N2for tires and tools – because they can get large bottles of it cheaply and avoid compressor maintenance. It won’t help your tires. If N2 actually leaked out slower, then refilling with regular air would soon result in a tire containing mostly N2, would it not, (as the smaller molecules leaked away, leaving the N2 behind)?
If you really want to try it, a good welding shop, or a BOC, Praxair, or Air Products terminal will give you all you need….
I’ll be using straight old air for my PCP, as soon as I take the plunge…..
Jane
Jane,
I’ll guess that most folk’s desire to use various other pressurized gases has to do with availability in their locale. If the closest dive shop is 50 minutes away, but there’s a muffler shop down the street…
Derrick
the shot that stuck in the barrel was while I was acting as spotter on 100 yard sight in. my friend may have failed to seat the eujin as it is very hard to do so…that was the worst time it happened.while unlikely the other times[pellet seating is one of my shooting peaves..]it is possible that I may not be 100%.I really think I had a malfunction,but your diagnosis is pretty plausible.thank you for your tech support.FrankB
Derrick:
Good point – if compressed nitrogen is more readily available, then there is every reason to persue it. I need to start checking around myself.
Thanks,
Jane
AF shooters……
Be careful about your silicone o-ring grease.
I got one of those little tubs from a hardware store and it caused all kinds of problems.
It was sticky nasty stuff that took quite a few shots to smooth out. On top of that, it was temperature sensitive. Did not take much change in temp to make a considerable change in how easy the breech would slide.
Don’t use it if you want consistency.
twotalon
Twotalon,
Thank you for the information on the hardware store silicone! I think I will remove that little tub from my airgun supplies now :).
.22 multi-shot
Tom, BB and Family:
Feliz Navidad and congratulations on your 1000 blog, as always thanks for the info, suggestions and advice.
Mario J.
ps. I could tell you that a friend and I bagged 30 pigeons and 5 iguanas today, him with his cf-x and i with my panther 34, but sadly is illegal to hunt with air rifles here in Puerto Rico
Merry Christmas everyone.
.22 multi-shot…..
I found some stuff at a local pool supply place called Jack’s formula 327. Expensive at 15 bucks for a little tube, but man that stuff is slippery.
Just need a little, and smooths out after a few shots. Maintains consistent viscosity over an extreme temperature range.
Ask on the talon website and you will probably get a dozen different choices. This product was the only thing I found locally that worked. Had it in my hand 20 minutes after I made a phone call. No regrets so far.
twotalon
Frank,
Yes, it does sound like a pellet seating problem because Eun Jin pellets are difficult to seat properly in the AirForce barrels. You need a pellet seating tool to do the job right.
I bet that’s what happened.
B.B.
twotalon,
Your Jack’s formula sounds suspiciously like the Dow-Corning 327 silicone grease I used to seal the AirForce tanks with.
B.B.
Jane,
I know you’re after a PCP, but do you have any springers at the moment?
Derrick
I have a Gamo CFX, (suprisingly nice – bought it after B.B.s review), a Crossman, (rarely use it), and the RWS pistol, all springers. I also have the Umarex 850 in CO2 – a very nice plinker.
None of them can deliver any energy very far.
Jane
B.B.,
Thanks for all the additional info on HPA tanks today. A lot of interesting comments, too.
The question of using nitrogen keeps popping up and I’ve heard a lot of anecdotal accounts, but I don’t think I’ve heard a single person say that they personally had used nitrogen in their PCP on a regular basis. I inquired at my local welding supply about using nitrogen, but there was annual tank rental cost (they wouldn’t sell a tank), they would only fill their tanks, and they wanted me to have an expensive regulator for the tank. After I told them I didn’t need a regulator because I would be filling an airgun, they politely told me to take a hike. Every place that sells high pressure compressed gasses understand how dangerous they can be, and they won’t take any risks with a non-standard application.
It really does seem that unless you are getting a very big personal favor from someone, a scuba shop or paintball shop are the only real options for buying HPA.
If anyone has personally done something else, I’d be very interested in hearing about it.
Thanks,
Lloyd
Twotalon,
Thank you for the recommendation. I just finished building my first unregulated PCP this Monday. I used diver’s 100% silicone grease to seal the o-rings and so far the pressure is holding. I’ll put Dow 327 on my list.
.22 multi-shot
Lloyd,
There is a welding combo paintball shop that I got my very first fill at. They filled with nitrogen, not air. If I remember correctly, their nitrogen tank was 4000 or 4500 PSI. They didn’t have a regulator, they just opened the valve slowly and watched until my tank got to 3000 PSI, then shut off the valve. It took several minutes and the operator was very cautious.
.22 multi-shot
.22 multi,
Thanks for the info on your local shop that really did use nitrogen. A welding-combo-paintball reminds me of the warning on the side of the fireworks I get that says, “Shoots flaming balls.” But all joking aside, I appreciate the nitrogen info. I wonder if anyone else uses nitrogen on a regular basis? Do you think its a rarity?
Thanks,
Lloyd
B.B.,
I forget to say congrats on the 1,000th blog. If anyone had asked you almost 4 years ago if you’d be able to come up with a thousand topics, and maintain the quality as you have so remarkably done, what would you have answered?
If it hadn’t been for this blog, I probably would have just dabbled in airguns for a short while, and then lost interest. Thank you very much for providing an intelligent and friendly place for us all to share the enjoyment of this sport. We all owe you a lot.
Best regards and a Happy Holiday,
Lloyd
BB and all:
Congrats on the 1000th post!
MERRY CHRISTMAS TO ALL,
AND TO ALL A GOOD NIGHT!
John from jersey
Lloyd,
My wife was the one who convinced me to start The Airgun Letter in 1994, by asking me to write the topics I could address in the newsletter on a sheet of legal paper. I figured I( could come up with enough topics for about six newsletters, which would have been 18-24 topics.
When I finished that exercise, I had over three hundred topics on paper, and I only stopped because I could see there was no end to it. The R1 book was actually born during that exercise, when I saw I could buy a gun and test it thoroughly enough that the material would make a book.
So when Pyramyd AIR asked me to write articles for their website, I knew there would be no end to what could be written. You see, it isn’t that I know a lot about airguns. It’s the fact that there is so much to explore and test. There is an unlimited amount of material here, and all I have to do is listen to all of you readers to pick the most interesting and pertinent stuff to explore.
Merry Christmas.
B.B.
RE: Nitrogen
Not a diver but a chemist. I’d concur that nitrogen wouldn’t ruin a scuba tank. To use for breathing just run it down to 400 lbs, purge a full charge of air to 400 lbs twice to be safe, and you’re ready to go.
There are two reasons that nitrogen would be interesting. Availability is first.
The second reason would be if detonation was a problem in some PCP. Since there would be no oxygen (ie very little…), you wouldn’t get detonation.
Herb
Lloyd,
I don’t know how common nitrogen fills are. I’ve only been to two paintball shops for fills. The second (a local shop), used SCUBA tanks for fills. Unfortunately they went out of business for a number of reasons. The economy, freeway construction in front of their shop and we are in a rural area.
The welding/paintball store told me that in their opinion, a dedicated paintball store is doomed to fail except in larger communities.
.22 multi-shot
.22 multi-shot,
Your words are sadly prophetic. I live in a rural subdivision (2 acre lots) in a county of 130,000 and my local PB shop is closing its doors on the 31st. What I will really miss is the 2 guys who ran the place. They knew their stuff and I could always pick up a tidbit of info on fittings or thread sealants or lubes. You know what I mean, the kind of personal help you can’t get at a big box store or from an online vendor.
I think these blogs and forums help to fill that void.
Lloyd
B.B.,
You said it. This hobby/sport/vocation offers limitless opportunities.
Thanks,
Lloyd
B.B.,
Regarding a carbon fiber tank’s lifespan – I know it is about 15-years typically. So after 15-years, can I still take the tank for a hydro test? If the tank passes both hydro and visual, can it still be used? Are there any laws/rules that say after xx-years, you MUST throw away your tank? Thanks.
Hydro,
I’m sorry to report that a carbon fiber tank’s life time is hard. Once they reach it they cannot be filled any more.
I plan to be filling mine from a compressor by then, so no problem.
B.B.
Did anyone else get the chance to see the MythBuster segment on compressed air tanks over Christmas? They rigged up a way to knock the top off the tank and it rocketed right through a standard cinder block wall and partially into a wall behind it.
The owner of our local dive shop told me a similar story. He thought he had drained a scuba tank because with the valve wide open no more air was coming out. In reality what had happened was a piece of rust had blocked the port. Thinking the tank was drained he unscrewed the tank valve and when it blew off the tank rocketed through two brick walls and into the bathroom. He is a luck man to have all his parts today.
-Chuck
RE: Mythbusters
Looked quite a while and couldn’t find that show on the interrnet. It was however:
Air Cylinder Rocket
* Show # 75
* Season: 4
* Episode: 21
* First Aired: 10/18/2006
Recap at:
http://www.tv.com/mythbusters/air-cylinder-rocket/episode/878206/recap.html?tag=overview;recap
Herb
C Jr,
How big of a hammer device did they need to knock the valve off?
Scuba tanks and valves and the method of handling them has been the same for years and years, but its always good to have reminder of what a freak accident might do.
Lloyd
Lloyd,
Now I wish I’d have watched it more closely to answer your question. I had company over for the holidays and I was trying to talk and watch at the same time. The episode I watched was called: “The Best of Myth Busters”.
I will describe it as best to my recollection but don’t hold me to any details. It looked like they rigged up a heavy steel plate that they dropped on the valve. In order to make that work they had to strike the valve on the very tip otherwise it wouldn’t break loose. The tank was lying on its side on the floor with the bottom of the tank pointed toward the wall about 20 feet away. When the plate dropped and struck the valve the tank shot straight arrow into the wall and punched a nice, neat, clean “wadcutter” hole in the cinder block wall they had built for this test and then punched part way through the building’s cinder block wall about 8 feet behind that. It was amazing how straight and true the tank shot across the floor. I think neither Jamie nor Adam thought it would go through the wall.
As a side note: during scuba training they instruct you to lay your tank down on the floor on its side if you are going to walk away from it. Many people forget this after training is over, yet I don’t hear any disaster reports of tanks screaming around dive sites. The way they’re shaped the valve would have to strike the top of a wall or bench or something like that. Based on how hard it was for them break the valve off it seemed relatively remote that a tank falling over would have its valve knocked off. However, that being said, we all know how alive and well Murphy’s Law is.
-Chuck