For many years (38) we have worked in tens of thousands of
applications in many industries and with customers who needed to
produce flames through hypodermic needles. We even have a special
division of our firm, which produces special flame head systems.
Under no circumstance should plastic hub hypodermic needles be used
for nozzles in any gas torches. It is unsafe practice on any torch,
including water welders, and this is clearly documented, even if some
manufacturers supply them with their units for cost saving reasons.
It is also an unsafe practice to just fit tips onto a tapered tube
for a torch. It is an unsafe practice to use a plastic hub tip in a
proper Luer fitting for a torch. It is not an uncommon event for
there to be an interruption of gas production, in piped, bottled or
generated gas systems. These factors cause a reduction of outgoing
gas pressure and for the gas in the tip retreat into hub and
detonate. We call this event a flashback, and it can propel the tip
at high velocity through the shop.
I have on several occasions seen a few of these plastic hubbed tips
imbedded in a ceiling or wall, and thought how lucky it did not find
an eye along the path of travel. There have also been examples of the
hub being deformed by heat and causing an unanticipated and larger
flame in a direction not wanted, burning the operator. Or fires
within the handpiece itself. There is also a difficulty in radiant
heat, reflection from your work softening the plastic hub of the tip
and creating the same unsafe event.
So, It is critically important only metal hubbed tips properly brazed
to the correct threaded nut as recommended by Alan Revere be used.
Or, as in our case, a complete metal male and female Luer fitting
connection which will retain the metal hubbed Luer tip even during
conditions of interrupted gas flow or a flashback. It must also be
noted in a detonation of gas at the tip, a plastic hubbed tip will
deform and easy come away from (launch) from a full Luer fitting.
This can leave one with a torch handle with no tip and an unexpected
very large flame, making a small problem into a much larger problem.
Our Spirflames[tm] generate a much smaller, and much larger flame
than other generators can use, but a dozen assorted metal hubbed
hypodermic needles, properly prepared with case only costs $60.00 per
dozen. These tips last many years with the minimum of care, so there
is no good reason to use unsafe plastic tips for torches in spite of
what may be supplied. Plastic hubbed tips are wonderful for use in
delivering solder paste, glues, gasketing materials, resins. Under no
circumstance should plastic hubbed hypodermic needles beused for
nozzles in any gas torches. If you wish additional documentation or
references, please feel free to contact me directly.
Gary W. Miller
Sr. Technical Advisor