Recertifying nitrous bottles?

I have two 10 lb nitrous bottles (from NOS) that appear to be in perfect condition but way out of date. One I bought new in the mid-90's, filled a few times, and haven't used since then. Anyway I'll need to get them DOT-recertified before filling. I believe the stamp is good for five years.

There does not seem to be any place in southern Missouri to get it done, though. Local welding gas place doesn't. One speed shop in Springfield (still 2 hrs away) sells N2O but doesn't recertify. They might have to go to St. Louis (3.5-4 hour drive from here!)...

Any thoughts?

When I owned a Scuba shop we had them tested at a gas supplier.

Is there a scuba shop near by? They may have arrangements to get them tested.

If not then maybe a medical supply company would know? They deal with Oxygen tanks.

Lastly find out from the local Cola company who tests theirs. CO2 has to be tested too.

Just food for thought Hope it helps.

If you have an Airgas distributor around they should know. Heck the welding ship ought to have too. They have to get their bottles certified too. Another possibility is the local FD, CO2 extinguishers need recertifying.

Thanks for the hints, I'll try those. You wouldn't think there would be much call for scuba diving here in BFE, Missouri... but Norfork Lake is only 50 miles away and people do dive in it. There are actually two listings in my otherwise waterless town of 12,000... go figure

Also we do have a Coca-Cola distributor. I'll ask them too.
The medical supply houses may or may not be helpful (ditto the local hospital). It's a matter of finding the right person to ask. NOT the $8/hr receptionist.

A fire extinguisher inspection/sales company should either do it in house or have a contractor.

Thanks. We do have one of those companies... a few years ago, I took an old empty CO2 extinguisher to them to pressure-test the bottle (only). That's all I asked for, not to certify it as an extinguisher or guarantee it for use. They did nothing for 2 weeks, then said "the valve was leaking so they couldn't test the bottle" but they'd be glad to sell me a valve for $95 and then test it (and charge more).
Haven't been inclined to do any more business with them. But I might have to grit my teeth and give them a call...

On FABO someone sent me a link to Marmic Fire & Safety which has multiple locations, the closest of which is Mtn. Home AR (40 miles away).
$38.50 plus tax to hydrotest each bottle, will take about a week

Next step will be finding a place that refills nitrous bottles, but one step at a time. I'm still dialing in my QFT 950, anyway

I live in St. Louis. I got my PADI dive certification at Lake Norfork in 1973. Fun times, camping at Buzzards Roost campground. Back then Hway 101 still had a ferry crossing the lake. Long gone, replaced by a bridge. Is the Scuba-Doo dive shop in Mountain Home still open?

A gas supplier should be able to do it. When they get bottles out of date, they need to test certify and re-stamp them before re-filling.
Many welding suppliers are not re-fillers, they just buy from the local AirGas or Linde distributor.
The hydrostatic test doesn't take that long itself, but after removing the valve from the bottle, it is filled with water and left to sit about a day for the temperature to stabilize.
After testing, they need to sit up-side down about a day to dry, unless they hook up a vacuum to the bottle.
I did that as a summer job at AirGas back around 1985. Very few tanks failed, but a few if the split a wall, I'd get drenched from all the water spraying out of the test chamber.
The test measured water displacement in the test chamber as the bottle is pressurized to see how much the bottle expands under pressure.

Look at the date of manufacturer stamped on the bottle. If it's too old, the testing site might not even test the bottle because of risk of bursting.
Chances are your bottles will pass the test, but won't won't be recertified because the bottles are past their lifespan. But, the lifespan of the bottle depends on the material the bottled is made from.
Some bottles have an unlimited lifespan. These are things to think about.

Here is a link about testing nitrous bottles

http://nitroustech.com/crown-markings/

Reminds me of the time we had to recert all the fire bottle on the destroyer I was on. Some of them were war booty and had past testing stamps with the Nazi eagle and swastika on them. Weird feeling, especially when you consider that the ship I was on wasn't even commissioned till more than 30 years after WWII ended,

As for the bursting concern, they are tested hydraulically and inside a burst proof container just to minimize that issue, any bottle can potentially burst under test.

Thanks for the info!
I'm familiar with the mechanics of the hydrostatic test. Already consulted with the Marmic rep who did not anticipate a problem with my mid' 90's stamp dates.
From the link you provided: "most nitrous bottles whose DOT numbers begin with 3ALM are required to be tested every 5 years, with an unlimited lifespan."
So I should be OK there.

My local Airgas would only order me a 50 lb bottle of nitrous, and didn't seem to be interested in hydrotesting my existing tanks.
Anyway I'll post back once I get the test results

So Airgas only wanted to get you new tanks, but wouldn't refill your existing tanks? Take a look anyway for the codes to confirm. Your's probably has the 3ALM. Maybe talk to some races and see where they get their tanks filled.

I just had this discussion with my gas supplier. He said that there are still oxygen cylinders in the system dating back to the early 1900's that were manufactured in Germany and have the swastika and Eagle. According to him they entered the market following WWI.

Bottles are recertified (and a really old flea-market 5-lb CO2 extinguisher too, had it recharged once it passed). Just have to go pick them up tomorrow

Now... what are people paying for nitrous oxide these days?

There is only one speed shop in my town and they want $75.00 to fill each 10-lb bottle
I know prices have gone up since the last time I paid $35 (admittedly 25 years ago) but that seems awfully high.

Most places around here are in the $6.50 per pound range. It is a lot higher than it used to be.
I get 73 lb mother bottles for around $235 and fill my own.

The two places I get it sell it for $5 per lb.

I'm planning on a mother bottle to fill my own bottles next season.

Thanks. I found a place in Mtn. Home (where I had the bottles recertified) that will fill them for $6.50/lb. They'll even go pick them up from the fire service place
I don't expect to be using it enough to justify having a mother bottle, since I'm on the street with street tires. Another 100-150 hp would just blow them off worse

Time for Drag Radials!

Looks like I got ripped off. I weighed the spare bottle, clearly marked on the original NOS label as 24 lb, 12 oz (when full with 10 lb).
On my digital postal scale it only weighs 21 lb 10 oz! So there's only 7 lb in it.

The one in the car is 24 lb 4 oz, so he "only" shorted me half a pound on that one.
Guess who's getting a call tomorrow...

And the credit card company if he doesn't have the right answers. At a minimum I'm doing a chargeback for 3.5 lb at 6.50/lb, and maybe more if he pissed me off.
Doesn't ANYONE do the job they're getting paid for any more??

Talked to the guy this morning. He was very defensive and insisted that he's been selling nitrous since 1992 and he doesn't do business that way.
So in his humble opinion I must have opened the valve, or it leaks (!). Despite that the cylinder is still 21.70 lbs today, hasn't changed a gram. As if I wouldn't have noticed and heard 3 lbs of nitrous leaking into my car (bottles were in the back seat) during the 1 hr drive home.

All he would agree to is for me to come down and he'd fill it up in front of me.
Sure, another 80 mile round trip and $10 in gas. And the bottle's at his house, not his shop, more time wasted.

At BEST his scales are wrong - which probably means he's been shorting people for decades. I will be charitable and assume it's unintentional.
Credit card will only dispute all-or-nothing. I just want $22.75 back, not the whole $130. He did provide 80% of what I paid for.
At this point the overpriced $7.50 nitrous in my own town looks like a better deal
And now I know why, of 26 Google reviews, there are 21 five-star and 5 one-star. Live and learn.

Did you weight your bottle before filling and is your scale certified. Maybe take your scale along next time.

It's surplus so hasn't been calibrated in a while... but that's easy enough to check (with a precise volume of water, for example).
And it's always agreed with the scales at USPS and FedEx.

More importantly - even if my scale is off, how could the weights be so different for two identical bottles, both labeled by NOS to weigh 14 lb 12 oz empty, 24 lb 12 oz full?
One is 21+ lb and the other is barely 24.

I need to go out of town for the rest of the week, so I will take this up again when I get home.

I have three brand new bottles that just ran out of cert. I have a new scale I bought for when I do run nitrous so I’ll try to weigh mine this week just out of curiosity. 1000’s of Dollars of nitrous stuff unused in my bedroom. Lol

For a minute there I thought your bedroom was in the garage

I've decided just to take the "short" bottle with me the next time I go to Mtn. Home, and tell him I want exactly 3 more lbs in it.
He did offer to fill it for free, with me present (that's all he would admit to).
That will be a full 10 lb, and then it doesn't matter whose scale is being used.

Then we'll be even and I'll never darken his shop door again. Anyone with the trifecta of bad attitude, late schedule, and blames the customer for HIS mistakes is not someone I do business with (more than once)