Scuba Tank Experts: (Questions) re: Hydro & Pricing

[0351_Vet]

I just p/u a M-Rod .25        (No Pump yet)    And wanted to do a cascade system (I think that's what its called)
with a 2 tank system. The questions I have are:

1. I found 2 - 80CF / 3300PSI with Reg Aluminum Tanks for $35.00 each. Last Hydro was in 2000.

Is this a good price for Alum 80's ?

2. If they Hydro'd in 2000 okay, should they Hydro now without a problem?

3. I found a place to Hydro for $40.00 each. Is that about right?

4. So, $35 for a tank and $40 for a Hydro, is that still okay unit price at $75.00 each?

5. What else would I need to purchase to fill the M-Rod, by filling with one and topping to +-3000PSI with the other?

6. Any other good advise would be appreciated.....Thanks S/F

[rsterne]

Aluminum 80 CF tanks are usually 3000 psi, not 3300....

Some aluminum tanks were made from an inferior alloy and either cannot be re-hydroed or are likely to fail....

The simplest way to make a cascade system is to use two "fill clamps" and connect the output of one to the gauge port of the other, like this....



Make sure the hose is rated for at least 3000 psi MSWP (more if your tank is actually 3300).... You do the first part of the fill with one tank, close the valve, and then top up with the other tank.... When the first tank is below the refill pressure of the gun, you take it out and get it filled and it becomes the "top up" tank....

Bob

[0351_Vet]

Bob,

Thank you for the info. I noticed in one post you stated that the life of a tank is only for 15 years?
If they were last Hydro'd in 2000......could they still be used after a hydro test? How often do you have to hydro, every 5 years?

[rsterne]

Carbon fibre SCBA 4500 psi tanks used to be a 10 year lifespan but that was increased to 15.... I hear rumours that may be going to be increased to 20 providing they pass the Hydro....

SCUBA tanks, AFAIK, don't have a regulated lifespan as such.... As long as they pass Hydro, you are good to go.... Hydros are required every 5 years, and visual inspections (valve off) every year.... Having said that, I have read that some shops won't fill an aluminum tank that is over 15 years old.... Steel, on the other hand are usually considered OK up to 40 years as long as they have a current hydro....

Bob

[lloyd-ss]

As Bob stated, some of the aluminum tanks from that era have problems.  A friend gave me an aluminum tank and it failed "eddy current  test", which detects internal cracks and defects in aluminum parts.  The eddy current is done before hydro on aluminum tanks.  $35 is a good price for the tanks, but you could loose it, plus the cost of the eddy current test too.  Unless the seller will let you have them checked first, I would be cautious.

You should ask at the scuba shop if they have an old "loaner" tank or two that still has a valid visual and hydro sticker.  I picked up a 3442psi steel 80 for $90 that way.  It was not pretty, but it was fine, and took the higher pressure.

With the Mrod, you can save money and live without the cascade setup, even if you have 2 tanks.  The Mrod is thrifty on air usage and the cascade systems are more needed for big bores where you would be going thru a bunch of air. 

Lloyd

   

[Data]

Aluminum 80 CF tanks are usually 3000 psi, not 3300....

Catalina tanks are 3300psi, Luxfers are 3000psi service pressure.

the eddy current test has only to be performed on certain luxfer tanks, older than born on date (first hydro) before 1988 (most shops won't even bother and just fail them)

[lloyd-ss]

Data,
Thanks for clearing that stuff up!  Yes, it was a Luxfer tank that failed the test.

[SAADE]

Some info on Alum tanks;  

How do I know if my aluminum cylinder is made from the 6351-T6 alloy?
Different manufacturers ceased using the alloy for production of SCUBA cylinders at different times. Luxfer phased 6351-T6 out over two years and had completely ceased using it by mid-1988, Cliff Impact ceased using 6351-T6 by mid-1990, Walter-Kidde ceased SCUBA cylinder production using 6351-T6 in 1989, and Catalina never used 6351-T6. The US Department of Transportation (DOT) issued an Advisory which identified in detail most 6351-T6 alloy cylinders (including many non-SCUBA cylinders) manufactured in the US. You should consult the advisory to precisely determine which cylinders are made of from the 6351-T6 alloy.

What is an eddy current exam?
This examination uses a tiny current of electricity and is performed on some types of aluminum cylinders to assist in the detection of cracks in the threaded neck area. It alerts the inspector to specific locations on the neck threads that need further evaluation. The devices using eddy current technology are sold under the brand names Visual Plus, Visual Eddy, and Simple Eddy. The exam is notorious for false results as a result of poor operator technique and is intended only to supplement, not replace, the visual inspection. Eddy current exams are not meaningful on any type of steel.

[SAADE]

0351Vet: A lot of folks have been tempted to buy "cheap" / used tanks over time and almost all of those folks have been very dissapointed with eithr the $$ they spent on testing and/or the expired life-cycle of the tanks (dive shops or fill shops that will not test or re-certify the tanks).

Wish I had a magic-bullet answer for you but... buy new, and buy carbon-fiber over aluminum or steel if weight is not a huge issue. Draeger, Luxfer, Scott are all reputable makers among others. Both SCUBA and SCBA types of tanks.

[0351_Vet]

Great info......Thanks for all the help. Geez, a lot to learn and know about (just in Scuba Tanks). I will let you know how it goes today as, I will be picking up 2 or 3 and send to hydro. I talked to my Air guy and he thought I should be okay with theses. Also the hydro includes a tank of air so in theory, I will be get each tank, plus hydro (5 years) and a 80 tank fill for $75.00 each.

Now, I just need to find the right "Yoke" set-up(s). Also I don't think I am going to fill over say 2800PSI or where ever the guns sweet spot psi is. Not really necessary from what I am reading and hearing from the PCP shooters. So, any suggestions on my filling set-up? And from whom to purchase?

Also, do they make like a 10 foot tether line so at the range you could stay hooked up to a tank for constant regulated PSI for sighting in purposes?

[SAADE]

0351Vet: "10 foot tether line..."  No, and it's one of the frustrating parts of using SCBA tanks, the shortest, smallest I.D. metal braided line is the best for filling. Not sure of all the dynamics at play here but, it's gotta be heat, pressure and losses through the longer line as my guess.

[rsterne]

For "constant regulated psi" you would not only need a remote line but also a regulator which has an output that would work for your gun.... In the case of a Disco, 1600 psi is the top of the sweet spot, in an MRod it could be as high at 3000 depending on how you have it tuned....

A 10 ft. line would lose you some air when you bleed it down.... The longest straight whip I have seen is 30".... You can get coiled hoses longer than that, but make SURE it's rated for the pressure you require.... In addition, the coils have a habit of straightening out when pressurized.... and it only takes them unwinding a couple of turns to be a royal PITA because they tangle up....

Bob

[RatRacer]

Also, unless its been tuned, .25 Mrods are tuned for 3k out of the box. .177 and .22's are tuned for 2.5k from factory.

[0351_Vet]

Also, unless its been tuned, .25 Mrods are tuned for 3k out of the box. .177 and .22's are tuned for 2.5k from factory.

Good to know......With that said......"Who is the go to guy for tuning M-Rods"?

[RatRacer]

For the .25,I believe that the only one at present that is communicating with anyone is Tony @ Talon Tunes. The other big namers are being quiet dealing with issues.

[aack73]

joe makes lines long enough to tether. he uses microbore line. not sure how long but you can tether. another member here "addictedtoair"  has one of these setups and its really nice.  try this link. http://www.airtanksforsale.com/

at what point you reach the $500 $600 mark for tanks etc i would seriously consider a large nitrogen tank. my .02.

[0351_Vet]

joe makes lines long enough to tether. he uses microbore line. not sure how long but you can tether. another member here "addictedtoair"  has one of these setups and its really nice.  try this link. http://www.airtanksforsale.com/

at what point you reach the $500 $600 mark for tanks etc i would seriously consider a large nitrogen tank. my .02.

If all goes well...I will be into the tanks, hydro'd and two - 80 tank fills for $150.00 (plus what ever the yoke or tethers cost me) That's far from 5-600.00....

I am trying to be a thrifty as possible, (and having picked up the .25 M-Rod new for 399.00 shipped.....I'll be off to the races for under 560.00 w/rifle and 2 -80's tanks full w/5 year Hydro).

I'm pretty happy, can't wait to start slinging big lead down range.

[only1harry]

I would be weary of a tank that is selling for $35.  You keep mentioning it was last hydro'd in '00, but you should also be looking at when the cylinder was manufactured - its age.  The date is stamped on steel and aluminum tanks.  If the tank is older than 20yrs old, I personally would not purchase them.  

I would look for a newer tank for $80-100 with a fresh hydro or 4yrs remaining.  I purchased a 2001 80cf SCUBA in May '08 with 4.6yrs left on the hydro for $85.  Figure with inflation the tank is $100 today even though it is older, or worse case scenario say $100.  That is a lot better IMO than buying a much older tank that you have to hydro yourself for a total of $75-80.  There is no guarantee the old tanks you are looking at will pass the hydro testing.

[Smaug]

As you can see, tanks can be their own kind of pain in the back.

Start with a good pump and save up for the tank in the meantime. You might find that you don't mind pumping, and have one less piece of heavy, bulky equipment to haul around.

With the Mrod, you can save money and live without the cascade setup, even if you have 2 tanks.  The Mrod is thrifty on air usage and the cascade systems are more needed for big bores where you would be going thru a bunch of air.  

Well, it will depend on a couple things. The .25 Marauder is going to be the LEAST thrifty of them, both with air and pellets. If you fill to 3000 PSI, then tune it to shoot soft, it may still be thrifty.

I don't know how this compares to the .25 Marauder, but I pumped my .177 Marauder to 3000 PSI last night and shot 50 rounds, and it is only down to 2600 PSI now. That is with the factory tune, which is probably about 950 fps with the 8.4 gr. pellets.

I'm thinking you can probably plan on getting 30 shots per fill on the .25 Marauder at factory settings with a 3k psi fill.

Also, I pumped up the Marauder from 500 PSI to 3000 PSI and it wasn't bad. One session of about 10 minutes until it got hot, and another session after it cooled to top it off of probably about 5 minutes. If it weren't run all the way down to 500 psi, I probably wouldn't have even needed to take the break.

[newguyontheblock (Nathan)]

i can definitely see wanting to get a tank after a full day of pumping and shooting.  there are also some of the folks here who just physically pump all day. a used tank and yoke should run you about 200 bucks, which is comparable to a pump? i think lol