DIYbanter - View Single Post - Welding Helmet fan pictures posted on metalworking dropbox.

wrote:

Helmet_Fan_explanation.txt

Very cool. I have just one nitpick: would you
mind resending the text file with hard carriage
returns every 70 or 80 characters or so? I
suspect that some of your text was truncated
where it exceeds the browser line length...
--Glenn Lyford

Hi Glenn,

The file has been re-sent, and is included below for your convenience.
Thank you for picking up on that snafu.

Guy

These pictures illustrate the integration of a Comair Rotron fan
into a Speedglas welding helmet. The purpose is to cool the user's
face and head. Also, the fan exhaust is directed downward and
prevents condensation from depositing itself on the lens.
Condensation often arises from the humid breath expelled from the
weldor and can be a nuisance. It also has a cooling effect that
is highly desirable during welding.

For those who perspire profusely, it is a welcomed relief.

Further benefits include the fact that greater proximity of the
user's face is possible with the fan without causing excessive
heating of the face, or fogging of the lens. This increased
proximity also results in improved field of view. Incidentally,
the stock headgear that comes with the Speedglas is not adjustable
in proximity distance to the lens. Another harness was substituted
to address this issue.

The reduction in heating and improved field of view reduced the need
to remove, or flip the helmet to a vertical position. This improved
productivity. Often, it was my experience that the helmet needed to
be flipped just to cool off.

Due to the proximity of the headgear to the fan, caution must be
exercised regarding hair length and placement. A couple of options
exist, including using some screening, or simply paying attention
to the hair and fan interaction.

The part number for digi-key is CR011-ND. The comair part number is
CR0212LB-G70.

Illustrations included that of the fan and mounting bracket. As can
be seen, the bracket was made from 16 gauge 316ss sheet. Some bends
were required to conform to the limited space between the helmet
elements and the headgear. The bracket could have been trimmed at the
boss, but the weight savings was marginal.

To affix the bracket to the bosses, 6-32 button head cap screws were
used. The bosses had to be tapped, and were pre-drilled to an adequate
size.

The Speedglas helmet has two bosses located just above the lens. These
bosses are no doubt used when the various accessories are added to the
base helmet, likely involving the bulkier fan that attaches to the user
and incorporates a filter, and some overhead gear to direct the air.

The screws used to hold the fan to the bracket are 4-40. The wires from
the fan were routed using zip ties affixed to existing elements of the
headgear and helmet.

The battery is affixed to the top headgear harness using a simple piece
of innertube. The top band of the headgear is adjustable, and allows
the inner tube section to be fitted easily. The 9V battery connector is
from McMaster. A switch was not incorporated into this implementation
to minimize component count. It is not really mandated since it is
relatively easy to turn on and off by simply connecting and
disconnecting
the battery.

Battery duration is higher than anticipated when using the rated current
consumed by the fan, and the amp-hour capacity of the battery. This is
an interesting benefit. The inner tube section allows the battery to be
easily changed, and is light weight. If the battery consumption were
higher, a transformer might be advisable, but this would impact
mobility.

If good ventilation isn't used, it is conceivable that the welding plume
be entrained by the fan especially if the plume rises in proximity to
the
top of the helmet. This poses health risks. The risk may be equivalent
to
that of using the standard helmet in the same environment. No studies
have
been made on this matter. The user should bear this in mind as with all
safety concerns.

Standard disclaimers apply.