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- since 1996 -
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Technical Discussions
Dave Utrata
R & D,
Center for NDE, Iowa State University, USA, Joined Feb 2000, 37

Dave Utrata

R & D,
Center for NDE, Iowa State University,
USA,
Joined Feb 2000
37
08:01 Jun-20-2003
calibration holes for leak testing

Good Morning all,

Wehave been performing quantitative studies of leak testing using a useful little setup that terminates in an end cap having a hole. We created a number of holes that range from the too-gross (0.03" diameter drilled) to the moderate (0.004" laser drilled) and have been able to document systematic changes in both bubble and acoustic detection, using orifice size, pressure differential, etc. as variables.

The big question: all these holes seem too big compared to the leaks we are asked to chase in real industrial situations. Does anyone have info/ideas on getting small(er) holes for use in our test system? Our next thought is to isolate and capture real leaks into a larger contraption, but that's looking a bit clumsy.

Thanks for your time.


    
 
 Reply 
 
Phil Herman Jr.
Sales, - Manufacture of NDT Reference Standards/Test Blocks
PH Tool Reference Standards, USA, Joined Oct 1999, 79

Phil Herman Jr.

Sales, - Manufacture of NDT Reference Standards/Test Blocks
PH Tool Reference Standards,
USA,
Joined Oct 1999
79
03:28 Jun-20-2003
Re: calibration holes for leak testing
Hello Dave,

PH Tool Reference Standards has machined very small calibration holes for leak testing for tubing mills. Most recent was a series of holes in .028" wall stainless tube. We EDM'd one through-hole per standard, with diameters of .0017, .0039, and .0079". The feedback I recall on the smallest hole was that it was TOO small. Contact me directly for more details.

Best Regards,
Phil Herman Jr.
President/CEO
PH Tool Reference Standards


: Good Morning all,
.
: We have been performing quantitative studies of leak testing using a useful little setup that terminates in an end cap having a hole. We created a number of holes that range from the too-gross (0.03" diameter drilled) to the moderate (0.004" laser drilled) and have been able to document systematic changes in both bubble and acoustic detection, using orifice size, pressure differential, etc. as variables.
.
: The big question: all these holes seem too big compared to the leaks we are asked to chase in real industrial situations. Does anyone have info/ideas on getting small(er) holes for use in our test system? Our next thought is to isolate and capture real leaks into a larger contraption, but that's looking a bit clumsy.
.
: Thanks for your time.
.



    
 
 Reply 
 
James A. Basford
James A. Basford
04:28 Jun-24-2003
Re: calibration holes for leak testing
: Good Morning all,
.
: Wehave been performing quantitative studies of leak testing using a useful little setup that terminates in an end cap having a hole. We created a number of holes that range from the too-gross (0.03" diameter drilled) to the moderate (0.004" laser drilled) and have been able to document systematic changes in both bubble and acoustic detection, using orifice size, pressure differential, etc. as variables.
.
: The big question: all these holes seem too big compared to the leaks we are asked to chase in real industrial situations. Does anyone have info/ideas on getting small(er) holes for use in our test system? Our next thought is to isolate and capture real leaks into a larger contraption, but that's looking a bit clumsy.
.
: Thanks for your time.
.
For many years we have been using 1/16" OD x 0.004" ID tubing welded into demountable flanges as flow restriction elements for calibrated leaks. The smaller gas flow rates needed for our calibrated leaks were obtained by crimping the end of the capillary tubing. Very constant flow rates from 1E-7 to 1E-2 atm cc/sec with gas source pressures from 1 to 20 atm are readily achievable. These are commercially available. I have also
made reliable orifices by drilling #80 holes (0.013" dia) in blind nickel gaskets and swaging them using a punch to get flow rates in the 1E-9 atm cc/sec range. For more information on calibrated leaks and leak testing, visit the web site of the American Vacuum Society, avs.org. Their Recommended Practices documents are be quite useful.


    
 
 Reply 
 
richard collins
richard collins
07:31 Jul-13-2005
Re: calibration holes for leak testing
: : Good Morning all,
Here at H.T.Products ltd we are leak detection specialists and also manufacturers of calibrated reference leaks of all types for most applications.We have a patent on a metal vacuum sintered leak which covers leak rates from typically 10e1 to 10e9 mbarlit/sec. They have the advantage of fast response, can tolerate high pressure differentials and high temperature are available for most gases with calibration traceability to national standards and re-calibration service available.We welcome your enquires.
: .
: : Wehave been performing quantitative studies of leak testing using a useful little setup that terminates in an end cap having a hole. We created a number of holes that range from the too-gross (0.03" diameter drilled) to the moderate (0.004" laser drilled) and have been able to document systematic changes in both bubble and acoustic detection, using orifice size, pressure differential, etc. as variables.
: .
: : The big question: all these holes seem too big compared to the leaks we are asked to chase in real industrial situations. Does anyone have info/ideas on getting small(er) holes for use in our test system? Our next thought is to isolate and capture real leaks into a larger contraption, but that's looking a bit clumsy.
: .
: : Thanks for your time.
: .
: For many years we have been using 1/16" OD x 0.004" ID tubing welded into demountable flanges as flow restriction elements for calibrated leaks. The smaller gas flow rates needed for our calibrated leaks were obtained by crimping the end of the capillary tubing. Very constant flow rates from 1E-7 to 1E-2 atm cc/sec with gas source pressures from 1 to 20 atm are readily achievable. These are commercially available. I have also
: made reliable orifices by drilling #80 holes (0.013" dia) in blind nickel gaskets and swaging them using a punch to get flow rates in the 1E-9 atm cc/sec range. For more information on calibrated leaks and leak testing, visit the web site of the American Vacuum Society, avs.org. Their Recommended Practices documents are be quite useful.
.



    
 
 Reply 
 
richard collins
richard collins
07:34 Jul-13-2005
Re: calibration holes for leak testing
: : Good Morning all,
Here at H.T.Products ltd we are leak detection specialists and also manufacturers of calibrated reference leaks of all types for most applications.We have a patent on a metal vacuum sintered leak which covers leak rates from typically 10e1 to 10e9 mbarlit/sec. They have the advantage of fast response, can tolerate high pressure differentials and high temperature are available for most gases with calibration traceability to national standards and re-calibration service available.We welcome your enquires.
: .



    
 
 Reply 
 

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