[Prev][Next][Index][Thread]
Re: Ovens.
Dear Al,
You can E-mail Jed Schleissner of GlowTube Neon (Wi). When he was visting
Holland and Germany last year he took a bunch of photo's from several
oven-pumpinstallation in the biggest neon factory here in Holland. Be aware of
the fact that you can hardly produce neon-filled tubes in an oven, so everyone
here have a bombarding-station as well. For sure one must use bricks for an oven
to anneal glass tubing. Glass is also only reacting to convection heat and not
to radiation heat, so never use the IR heaters but only the spirals. Ther are
spirals installed in the bottom and the wall around of the oven. The purpose of
that is that the bricks are functioning as a conductor and they are actially
heating up the glass. There are some parameters that you must follow and one of
them is that there are several hysteris temperatures of about 5 minutes at a
specific temp. By these temps the glass will let out of the wall hydrogen and
oxygen. These rate's are very narrow and therefore they are always here
electronicly controled.
The proper heating up time of neon tubes is in about 75 minutes to the maximum,
and the cool down period must be 1C a minute. So the cool down period of
sodalime or lead no lead glass is 8 hours to do it properly. Therefore heating
up and cool-down always take place during nighttime when we pay less then halve
the price for electricity. The cool-down cycle of 1 C a minute is very important
becouse when you cool down quicker, let's say in a few minutes, the glass is not
annealed. On the contrary, the glas will be filled with strength.
All the ovens I know here in Europe are electrical heated and never any longer
by natural gas and benders never use a torch to anneal or degas the wall of the
tube. The right temperatures are so essential for pump out hydrogen. All the
ovens I know have a top-lid and can pump 40 to 50 pieces of glass together in
one oven at the same time. So using a modern oven is much and much quicker then
any other pumping system. The dimensions of an ordinary oven are 2,5 till 3 mtrs
long - 1 till 1,5 mtr wide with a heigth of 1 meter. The installed electrical
power for an oven like this is about 14 kVA, so we pay about $ 1,-- for pump and
anneal 40 tubes. If you want to have more specific information E-mail us.
Best from dirk a. boonstra