How many of you test your tanks?

[Case Stuffer]

SCBA and other HPA tanks  grow old and fail due to metal fatigue due to work hardening caused by expansion and contraction. The amount of fatigue induced each cycle is related to how low it is discharged to and off course its maxed charged to pressure. A cylinder discharged to zero to 200 PSI and charged to 4,500 experiences more stress than one discharged to only 2,000 and charged to 4,500.   


So why 15 years service life

http://www.phmsa.dot.gov/pv_obj_cache/pv_obj_id_DD40218680269DDB4602688C3BFA523D45C70900/filename/FINAL-Report-SCBA_Cylinder_Life_Extension_Study_09202012.pdf


Snip

The  U.S.  Department  of  Transportation  (DOT)  in  the Code  of  Federal  Regulation  (CFR)  49, Section  180.205  mandates  maintenance  requirements  for  SCBA  cylinders.  Glass  fiber-reinforced plastic   (GFRP)   and   carbon   fiber-reinforced   plastic
(CFRP)   SCBA   cylinder   maintenance requirements  were  established  in  the  early  1990s  based  on  cylinder  manufacturer  input.  At  that
time,  there  was  extensive  experience  with  aluminum-alloy  tanks  but  very  little  knowledge  of  the long-term durability and strength characteristics of fiberglass or carbon fiber. A lower limit on the service life of composite-wrapped cylinders was established at 15 years based on limited studies on the  durability  of  fiberglass  observed  in  testing  for  NASA  aerospace  applications.  The  15-year cylinder  life  is  also  linked  to  cylinder  cycle  testing  (fill-and-empty  cycles)  at  the  time  of manufacture,  when  two  percent  (2%)  of  all  cylinders  manufactured  are  cycled  10,000  times (corresponding  to  about  one  cycle  per  working  day  for  40  years),  then  subjected  to  a  number  of strength  tests.  Cylinder  manufacturers  submitted  that  this  testing  established  a  threshold  level  of acceptable  safety  that  can  be  reasonably  expected  over  a  15-year  service  life  (regardless  of  the working gas).

15/40=37.5%

37.5% of 10,000=3,750

Added to clarify:

So  number of safe fills is 3,750 based on fiberglass wrapped not CF  wrapped and based on fill-and-empty  cycles which routinely are closer to  0 PSI than the 2,000 min. most air gunners would use.


3,750 (cycles) / 15(yrs.) =250 fills per year.

Some likely feel that I just want to argue this point but honestly I just want others to realize that the DOT regulations are  based on 1990's data and not even on CF wrapped  tanks much less on CF tanks used / handled the way ours' are.  

[Case Stuffer]

What makes an average useage as to the number of fill cycles for an air gunner?

I have read many post of those who get their tanks filled once a month or so and then there are those who have a fill last much longer.
 

Re: Crosman's New PCP Fill Chart
« Reply #18 on: June 15, 2014, 10:57:58 PM »

 
With these numbers the calculator reports that 46 refills are possible.
Or about one a week for a 10 1/2 months.
Also 46 fills will power about 5000 shots, one sleeve of pellets

This is fairly close to my experience.  Historicall, I fill the SCUBA tank, refill 11 months latter to avoid visual inspection costs, and then when it needs a fill for real, about 18 months after the 11 month fill. It also agrees with my pellet burn rate of about one sleeve per year.  Which for me is a lot of shooting.



    Enterprise, al

So
One fill used for  11 months  then refilled (topped of to avoid annual inspection) then 18 months later a real / needed fill.
Two fills equal 29 months of useage. 


I have a Guppy CF 45000  18cf (or perhaps 17cf as I have seen it listed both ways) which last me about a week.Guppy filled to 4500 used down to 3000 which is approx.15 fills for Disco  from 1,000 to 2,000. This is a total of approx. 350 pellets down range.

I live in the country , have 5 acres (normal for my neighborhood) ,I am retired so  able to shoot daily  most of the time ,weather permitting.

3,750 (conservative number of  safe useable cycles) / 52 wks. = 72 years