|
from CAB Seminar talk entitled "Atmosphere
Control"
Furnace atmosphere consumption is a function of the
configuration of the heating chamber, input and control
system. The following are some nitrogen conservation
measures that can be incorporated in your scheduled maintenance
program:
- Maintain integrity of entrance and exit chamber curtains -
Curtains that have been properly sized and are in good
condition can do an exceptional job of sealing the
furnace. Curtains should make contact with the furnace
belt, and the chamber should be designed so that the total
length of curtain is 2-3 times the length of the typical part. The part
should be able to pass beneath the curtains without tipping,
snagging or causing permanent deformation.
- Proper Dry-Off Oven Operation - Proper oven
temperature is necessary to assure that the entire part is
heated enough to evaporate water. Purging may be
necessary to remove trapped water vapor from the parts.
This may be done with a hot air knife at the exit of the
oven. The oven must have adequate circulation and
venting to remove water vapor. If the oven exhaust
and recirculation capacity is inadequate, it will be
impossible to remove water vapor from the parts.
- Auxiliary Purge -Large parts or those being brazed
with tanks may require the use of a high pressure nitrogen
lance. The lance should be positioned so that it injects
nitrogen into one opening expelling air out of another.
It may be beneficial to add a sparge pipe in the top of the
entrance purge chamber - this would force any trapped air out
of the part as it passes beneath the curtains
The latest design, materials
and equipment specifications should be obtained from the company
before any reliance is placed on the enclosed since changes may
occur due to product improvement.
|
