I'm thinking of the upcoming winter when I need to, as my wife puts
it, bond with my welder. So that means welding in the basement, for
which I know I need a fume exhaust system. As usual, I intend to
build my own cheap. The surplus store has a pretty good selection of
blowers, but I have no idea what size I need (CFM). Can anyone help
me here?

On Fri, 5 Sep 2008 12:34:19 -0700 (PDT),
wrote:

I'm thinking of the upcoming winter when I need to, as my wife puts
it, bond with my welder. So that means welding in the basement, for
which I know I need a fume exhaust system. As usual, I intend to
build my own cheap. The surplus store has a pretty good selection of
blowers, but I have no idea what size I need (CFM). Can anyone help
me here?

What kind of welding?

On Sep 5, 4:37*pm, Don Foreman wrote:
On Fri, 5 Sep 2008 12:34:19 -0700 (PDT),
wrote:

What kind of welding? *

MIG - shielded and flux core, but mostly shielded. It's a small
welder - 120VAC, 20A.

wrote:

I'm thinking of the upcoming winter when I need to, as my wife puts
it, bond with my welder. So that means welding in the basement, for
which I know I need a fume exhaust system. As usual, I intend to
build my own cheap. The surplus store has a pretty good selection of
blowers, but I have no idea what size I need (CFM). Can anyone help
me here?

Where are you located? I have a rig I used to use a lot but since I
switched to MIG I don't anymore.

Grant Erwin
Kirkland, Washington

wrote:

On Sep 5, 4:37 pm, Don Foreman wrote:

On Fri, 5 Sep 2008 12:34:19 -0700 (PDT),
wrote:

What kind of welding?


MIG - shielded and flux core, but mostly shielded. It's a small
welder - 120VAC, 20A.

Just weld with it. Not many fumes.

Grant

On Fri, 5 Sep 2008 14:01:24 -0700 (PDT),
wrote:

On Sep 5, 4:37*pm, Don Foreman wrote:
On Fri, 5 Sep 2008 12:34:19 -0700 (PDT),
wrote:

What kind of welding? *

MIG - shielded and flux core, but mostly shielded. It's a small
welder - 120VAC, 20A.

Couple of hundred CFM (like a bathroom fan) would probably suffice
for MIG. The blower from an old clothes dryer might work great, and
it's designed to work with vent pipe that can go to outside from a
basement.

Fluxcore does generate a fair volume of smoke. Try it, see how
smokey it gets in your space while it's still warm enough to air it
out with a big fan.

wrote:
I'm thinking of the upcoming winter when I need to, as my wife puts
it, bond with my welder. So that means welding in the basement, for
which I know I need a fume exhaust system. As usual, I intend to
build my own cheap. The surplus store has a pretty good selection of
blowers, but I have no idea what size I need (CFM). Can anyone help
me here?


Measure the length, width and height of your basement to figure out the
cube (l X w X h). Then decide how often you need to change the air
(every minute, every five, etc) and get a blower that will move air at
that rate. Of course, you are going to have to have an intake SOMEWHERE
so that that cold, fresh, outside air can replace what you've removed.

Jim

Your CFM requirements are largely a function of how far you let the
smoke disperse. If you can capture the smoke within a few inches of the
weld, you only need a couple hundred CFM. If you let it propagate
throughout the whole shop, you need one several times that and it will
take a while to clear the smoke.

One thing I like is to do a fume hood sort of thing: Assuming fairly
small projects (less than a 2' cube) set up a 3 sided booth around the
weld bench, add some wings to tuck in close to your body, seal the top,
and add your fan. The fresh air will be coming in around you, the total
CF of contaminated air is very small, a bathroom vent fan is quite
sufficient.

Your fan needs to deal with both a CFM rating and a water column rating.
You will find that a lot of the muffin fans are the right size, will
move a lot a air when in free air, but just won't push much of any air
through a vent pipe. Most any centrifugal unit will be MUCH better.

I worry about welding in the basement. The little sparks like to roll
off into the corners, start fires hours later. Unless your weld area is
completely free of junk, dust, sawdust, etc, you are always taking a
chance.

wrote:
I'm thinking of the upcoming winter when I need to, as my wife puts
it, bond with my welder. So that means welding in the basement, for
which I know I need a fume exhaust system. As usual, I intend to
build my own cheap. The surplus store has a pretty good selection of
blowers, but I have no idea what size I need (CFM). Can anyone help
me here?

On Fri, 05 Sep 2008 21:46:13 GMT, with neither quill nor qualm, Grant
Erwin quickly quoth:

wrote:

On Sep 5, 4:37 pm, Don Foreman wrote:

On Fri, 5 Sep 2008 12:34:19 -0700 (PDT),
wrote:

What kind of welding?


MIG - shielded and flux core, but mostly shielded. It's a small
welder - 120VAC, 20A.

Just weld with it. Not many fumes.

Bad karma, Grant. _Any_ smoke in the house is bad smoke. A new or
used range hood/fan would work great for Bennet's needs and his family
(and doctor) will thank him for its installation.

Bennet, diffuse the incoming air so it doesn't disburse the gases from
the welder.

--
Who is wise? He that learns from every One.
Who is powerful? He that governs his Passions.
Who is rich? He that is content.
Who is that? Nobody.
-- Benjamin Franklin

wrote in message
...
I'm thinking of the upcoming winter when I need to, as my wife puts
it, bond with my welder. So that means welding in the basement, for
which I know I need a fume exhaust system. As usual, I intend to
build my own cheap. The surplus store has a pretty good selection of
blowers, but I have no idea what size I need (CFM). Can anyone help
me here?

All welding produces toxic fumes. Some is "just" smoke, other stuff will
make you sick or cause cancer. ALL of it is dangerous with long exposures.

The thing is, it is better to build a hood where when you are welding, the
smoke is drawn out the hood quickly. A fan can be put under also to create
a positive air flow. What this does is lessen the time to empty the smoke.
If you just weld, the smoke goes into the entire basement. Now you have to
dump all (or more) of that WARM air to get all the smoke out and replace it.
Heating costs rise.

If you have a hood, you just vent it when you are welding, and you don't
have to replace the entire volume. You can also have cold air ducted in for
the positive feed, and you will have minimal WARM room air exhausted.

Welding in confined spaces is a no brainer. Let's make smoke and stand in
it. What's wrong with this picture? How you lessen the exposure is the
important part here.

Now, if you're rich, and don't mind what it is going to cost you to heat
your basement every two hours, please e mail me, as I have some financial
schemes I think you will find interesting.

Steve, welder since 1974
certified lunatic
certified welder, too

"RoyJ" wrote in message
m...
Your CFM requirements are largely a function of how far you let the smoke
disperse. If you can capture the smoke within a few inches of the weld,
you only need a couple hundred CFM. If you let it propagate throughout the
whole shop, you need one several times that and it will take a while to
clear the smoke.

One thing I like is to do a fume hood sort of thing: Assuming fairly small
projects (less than a 2' cube) set up a 3 sided booth around the weld
bench, add some wings to tuck in close to your body, seal the top, and add
your fan. The fresh air will be coming in around you, the total CF of
contaminated air is very small, a bathroom vent fan is quite sufficient.

Your fan needs to deal with both a CFM rating and a water column rating.
You will find that a lot of the muffin fans are the right size, will move
a lot a air when in free air, but just won't push much of any air through
a vent pipe. Most any centrifugal unit will be MUCH better.

I worry about welding in the basement. The little sparks like to roll off
into the corners, start fires hours later. Unless your weld area is
completely free of junk, dust, sawdust, etc, you are always taking a
chance.

wrote:
I'm thinking of the upcoming winter when I need to, as my wife puts
it, bond with my welder. So that means welding in the basement, for
which I know I need a fume exhaust system. As usual, I intend to
build my own cheap. The surplus store has a pretty good selection of
blowers, but I have no idea what size I need (CFM). Can anyone help
me here?

An enclosure is also functional from a fire safety point of view.

Steve

You've received very good suggestions for venting. Venting is definitely
needed because you won't generally feel the effects of the smoke
immediately, but the health risks are well documented.
There is probably (required by law, I believe) a MSDS sheet glued to the
spool of welding wire when it's purchased.

I have welded in a basement shop, and right at the top of the list for
safety equipment is a suitable and adequate fire extinguisher mounted within
easy reach (no more than a couple of steps away, mounted on a column with
easy access from any direction and no clutter in the way, in my case) .

In addition to the fire extinguisher, I always want to have at least one
large trigger spray bottle with water for for small oh**** moments like
catching a ball of hot splatter in a wrinkle of clothing or some other minor
incident requiring rapid/quick spot cooling.
They both accompany me when I'm soldering plumbing, too.

It would be very bad practice to leave the welding area immediately after
welding.

The point of having a replenishing air supply is particularly vital if there
are gas appliances in the structure.
Creating a negative pressure indoors can draw carbon monoxide into the
occupied space.

Homes/buildings with gas appliances need to be monitored with at least a
couple of CO detectors/alarms, and there isn't any rational reason for not
having them (and testing them).

Having all of the proper safety equipment and an adequate amount of the
proper tools will make the welding practice/experience sessions much more
enjoyable, and most likely allow you to achieve your best performance (and
make the skill gaining experience much easier).

WB
..........
metalworking projects
www.kwagmire.com/metal_proj.html


wrote in message
...
I'm thinking of the upcoming winter when I need to, as my wife puts
it, bond with my welder. So that means welding in the basement, for
which I know I need a fume exhaust system. As usual, I intend to
build my own cheap. The surplus store has a pretty good selection of
blowers, but I have no idea what size I need (CFM). Can anyone help
me here?

On Fri, 5 Sep 2008 12:34:19 -0700 (PDT),
wrote:

I'm thinking of the upcoming winter when I need to, as my wife puts
it, bond with my welder. So that means welding in the basement, for
which I know I need a fume exhaust system. As usual, I intend to
build my own cheap. The surplus store has a pretty good selection of
blowers, but I have no idea what size I need (CFM). Can anyone help
me here?

The room you weld in HAS TO HAVE totally sealed and properly drywall
walls and ceiling, primed and painted to protect the paper outer
layer. There is both radiant heat, flying sparks, and flying white-
hot weld metal "dingleberries" that can catch walls and ceilings on
fire.

All access hatches in the walls and ceilings for plumbing or HVAC
need to be non-combustible metal.

I would suggest fire sprinklers for the basement room you will be
welding in, even if you buy the heads from McMaster and braze up a
system yourself out of copper pipe. Flow switch and alarm bell, and a
shutoff ball valve & drain valves for repairs.

I'll do this when I build the little closet around my air compressor
- too much heat in too small a space is a recipe for trouble.

For fumes, if you will be working on little projects on a welding
table, they make tables with a grid top and a pan to catch the slag -
and you can easily attach a duct on the bottom and suck the fumes down
through the table top and outside.

Make the first few feet of the duct with the solid sheet-steel duct
or segmented elbows turning to go up the back wall, in case any
dingleberries get inside - they'll melt right through vinyl dryer
ducting, and the aluminum foil flex duct won't last too much longer.

They make "Inline" or "Duct Booster" fans that splice into a section
of 4" (dryer) ducting, and can handle some reasonable static
pressures. Send the fumes outside like you would rig up a dryer
exhaust. And put a range hood over the table to get the fumes that
still insist on going up.

-- Bruce --