Having designed and manufactured equipment intended for both low and high pressure (industrial) gas service, including oxygen, the general risk of ignition in compressed air systems is always something to consider; however briefly.
Note that there are a multitude of possible ignition mechanisms...
And the worksheet(s)https://files.engineering.com/getfile.aspx?folder=415a7522-be42-47bd-b480-c2396bce6658&file=Gas_Flow_Noise_Estimation_Update_230503.xls
I came across this thread and got curious on the topic; so I reached out to Nelson as well. He was very forthcoming with the documents, sending me a copy with his personal updates - in the spirit that NASA intended as a public service.
With that in mind - see attached documents for the Design...
As a small private-owned company that designs a multitude of equipment and systems for (mostly) the industrial gas sector (or any industry that might use this industrial gases in their production), I can relate to your struggle. We have a large project going on with a German supplier that also...
"Or are you telling me that the machine doesn't see the difference" - It depends on the machine. Most of them does differentiate between nominal and actual tolerances(Not older models, you would be surprised how many manufacturers uses equipment from the 40's, 50's and 60's still in some part of...
"2. I suppose, for a machinist, the tolerance band would be the one dictating the machining hours required, machine capability and subsequently cost, rather than the number of decimals. Haven't myself worked directly with a machine, I am assuming that keying in 5 decimals into their programming...
Hello everyone,
Our production is intended for oxygen service (industrial and medical), meaning everything has to be cleaned for oxygen service in accordance with strict standards. We have a range of inspection methods employed to qualify the cleanliness of the final product; including Direct...
I second what ctopher states; most of the European manufacturers I have worked with also demands hard dimensions and tolerances, and will measure to those tolerances. I work with older machinists from eastern Europe; I can't tell you how much I learned from those guys over the years - and it...
LittleInch - Its always fun when the customer insists on 6 mm and 10 mm sizes, and you explain that when it comes to flexible hoses its 1/4'' and 3/8''. The real fun begins when the customers demand 6.35 mm hose, calls it a 6 mm hose and refuse to accept the term 1/4''; demanding all drawings...
Hello everyone,
Rubber and plastic (flexible) hoses in oxygen system often incorporate what is a called a distance piece, and is described in ISO 14113. In short it is there to lessen the effect of adiabatic compression. Now the standard describes that the distance piece should have a volume of...
My experience is from the industrial gas industry, mostly regarding the design of high pressure oxygen systems. Form follows function. If I need a part to be made in a particular way, it's for a reason. If the part can't be made with existing tools and methods, we make new tools that allows it...
Hi,
It is a nice formula, but what are you trying to accomplish? Sealing against vacuum is tricky depending on the sealing configuration.
Static, dynamic, face seal? Dovetail configuration? Half-dovetail? If it is hot water then an EPDM material should be considered as a material.
Further I...
Like 3DDave states the typical geometry allowances are to provide mechanical clearances for typical taps and dies. Often it is defaulted to 1.5-2 x P or 2-3 x P. Now there are of course taps that have shorter runouts, like 0.5-1.0 x P, typically called (chamfer) form E or form F for an even...
desertfox - thank you for the input and the document; I am looking into it.
mfgenggear - It does have a hex; and yes - potential metals to use is very limited due to the need for oxygen compatibility.
My initial impression after visiting the plant is that it is a fault with the torque tool used...
Desertfox - Hi again, I have seen those before, but I never knew the final torque figure should be achieved by hand to avoid over-torquing!
"Have you run any calculations to estimate the stress in the threads? It might be worth doing that and comparing it with allowable stresses." - I tried at...
3DDave - All good points and I will do that. I have also reached out the the customer to see if they can to the same on their end with the valve manufacturer(s) - they are looking into it; to make sure the valve is indeed made out of the previously stated material/alloy. Correct, I have our...
3DDave - Correct. And as you point out, all it takes is a worker that messes around. Which is why designing for oxygen service includes reducing the need for lubrication as much as possible.
I will find out more next week; if nothing else it should be an interesting exercise in "trust but...
TugboatEng indeed there are! I spoke with a Krytox supplier and they could only offer Krytox NRT8908 for 230Bar oxygen cylinder pressure, which was crazy expensive. Other alternatives include types of Fomblin, Kluberalfa and Gleitmo that are all BAM/CTE/WHA certified for oxygen service. A thing...
Then again, if a random country uses W21,80x1/14LH for Oxygen I wouldnt be surprised. I have seen many, many weird connections. Like left handed threads for a non-flammable gas mixture with 0.019% hydrogen. Or W24,32x1/14 for SF6 gas mixture.
