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Ventilation system


Hello, I am looking for a good ventilation system for home use. I
only need something for occasional soldering fumes. A nice small
unit I looked at was $500.00. That seems like a lot of money for
something I will only need once in a while. Can an open window and a
hepa filter suffice? If not, how much does an affordable unit cost
and where can one be obtained? Thanks all, Augest of Cry Baby Designs


Hi Augest, There is an overwhelming amount of on setting
up home ventilation systems in the Orchid Archives – just go to and type in your
query. You can search by year, or by the entire archive (which I’d
suggest for this one). Orchidians have posted many helpful
suggestions for ventilation systems in all price ranges, from
home-rigged motors and fans to fancy shop-sized ones. But definitely
get yourself hooked up with something that actively pulls the air
from your workplace - an open window and filter really doesn’t cut it
if you’re doing anything more than just sawing and filing metal.

Best of luck,
Jessica, safety monitor in San Francisco


Hi Augest,

 I am looking for a good ventilation system for home use. I only
need something for occasional soldering fumes. 

Some folks won’t agree with what I’m going to say, but I’ll still
stand by it.

If as you say, you’re only going to do ‘ocassional soldering’ & the
soldering is the typical silver & gold soldering, if you can do it
in the kitchen with your stove exhaust fan on you’ll have all the
cventalation ou need. That also assumes you have normal health & no
respitory problems.

It’s also a good idea to stay away from flues & solders that contan
flourides & cadmium.



I have been experiencing some breathing problems whenever I use my
acetylene torch or grind and file, and polish sterling with silicone
pads using my drummel tool. I have decided that I need good
ventilation and need advice as to the kind of system that will work
for a small time jeweler. I have outfitted my furnace room with a
work bench, tools, rolling mill and drill press. The furnace room is
adjacent to my garage which is where I have set up my torch. I have
purchased the following: a 6 inch vent which will be installed over
my outside door next to the garage door. Into the vent I was going
to attach a 6" stove pipe and then a fantect 400 cfm fan and continue
the pipe to a y adaptor which will have two back draft dampers. From
each dampers I will attach flexible hose ending in a hood. One hood
will be set up to deal with the torch and the other will come out of
a hole in the wall leading to the furnace/work table…flexible hose
and then hood where I grind, polish, saw and use my drill press
Someone told me that I could be setting up some negative charges in
my furnace which could lead to carbon monoxide poisoning and destroy
my furnace. So, I am confused as to how to set this up so it is safe
and efficient. I have put a lot of time, electrical work and effort
into creating the work area in my furnace room. I have problems
wearing the 95 respirator masks has been recommended by a welder. I
have looked at sites like Lampwork etc. and this seems to be the
system that they recommend. Long winded question but my health could
be compromised if I do the wrong thing.

Any advice? regards, Barbara


Hi Barbara, I’m a bit confused about the statement grinding, sanding,
polishing and using a drill press could set up neg charges in a
furnace and lead to CO poisoning and a destroyed furnace. I have
never heard of anything like that before, hopefully someone else can
clarify. As I understand your description you will have an
inefficient system. Fans blow much better than they draw. How much
cfm will be moved by your fan is also dependent on how far you run
the tubing. You may need to put a fan directly after the hood as well
as an inline or end fan to clear fumes. You will also need make up
air to replace what the fans remove. Do you have breathing problems
in the furnace room only when making jewelry? It seems odd that using
a torch or grinding/filing or polishing causes you problems breathing
I could see one of them but all? Might want to check the furnace room
for air quality, your furnace could be the source of your breathing
problems or mold if the furnace room is damp.

Good luck with it, Jim Doherty


HI Barbara

Before I retired a couple of years ago, my day job was as an
Occupational Health and Safety person. A lesson I learned more than
once is that designing effective exhaust ventilation systems is
difficult and can be quite expensive. Here are a few things to keep
in mind:

  • There is a big, big difference between sucking and blowing air.
    Its much easier to blow air where you want it than to effectively
    exhaust a process. Lots of things interfere with good exhaust
    ventilation. For example, every right turn in the duct work reduces
    the air flow by 40-50 % so keep ducts as straight as possible. Longer
    ducts reduce air flow. Flexible duct design causes turbulence and
    reduces air flow significantly. Flex duct frequently has lots of
    twists and turns, each one detracting from the exhaust efficiencyy.
    Just because they did it at the factory next door does not mean it is

  • The hood, hose or other intake needs to be as close as possible to
    the source of contamination. 90% of the velocity of exhaust
    ventilation is lost in 1 diameter from the entrance. That means if
    you have a 4 inch exhaust duct hose exhausting air at1,000 feet per
    minute at the hose face, 4 inches out, you will only have a velocity
    of 100 fpm. So get your work close to your hood or vice versa or you
    will not have enough velocity to capture and transport the

  • Its very unlikely that you are producing fumes, vapors, or
    particulate at levels that are a significant health hazard. We tested
    a lot around hand welding in electronics assembly and never found
    dangerous of lead or other metals. That is because the melting point
    is far enough below the boiling point where lots of fume would be
    given off. Kilns are a horse of a different road clearance. The
    particles given off by polishing, hand sanding etc are usually not a
    size that would penetrate the body’s defense systems and cause
    chronic health problem.

  • You could probably filter the air and return it to your work room
    rather than exhausting it to the outside and do just as well. For
    toxic work products, outside ventilation is needed, for nuisance
    dusts and such, filtering ad return is probably adequate.

  • There is ventilation/filter equipment available. I have not been
    looking at this kind of stuff for several years so I 'm not sure
    whats out there, I did find this at Lab Safety Supply Co.

a portable fume extractor. I don’t know the cost of anything about
it but it looks like it could be used for much of what we do. Or you
might think about using a vacuum cleaner for specific operations-
buffing sanding etc.

  • I personally use a 3M Co dust fume and mist respirator (one of the
    paper things) some of the time. I have a plan to set up a shop vac
    to capture particulate from polishing and buffing, more for
    housekeeping than for health reasons.

Hope this helps. Feel free to contact me off line if you have any
questions and I will try to answer them.



Barbara, I think that you will find that the 400 cfm fan is
inadequate for your needs. I don’t know how many square feet are
contained in your studio but much of the power of the fan (hp) will
be used up by the friction loss of the duct work. Air is like very
thin water and offers resistance to the side of the duct just like
the surface of a pipe or hose offers resistance the flow of water. In
order to provide adequate flow for all of your various desires,
soldering hood, polishing station and general room exhaust, you will
most likely need much more then the 400 cfm that you have allocated
with the fan you have chosen. That cfm listed is with no duct work
attached to it, no resistance. Air is different then water in the
fact that it is compressible and water is not. With this in mind
there is a possibility that you could have no air being exhausted out
of the studio. If you look at a wood working dust collection system
for design purposes you will see an approximation of the size of fan
and duct work needed to have a satisfactory system. I suggest that
you use a furnace pre- filter for the polishing station. My personal
guess of a fan is in the area of 800 to 1,200cfm, more towards the
higher number I think.

Good luck with your system, Jerry

Someone told me that I could be setting up some negative charges
in my furnace which could lead to carbon monoxide poisoning and
destroy my furnace. 

You really need to be careful about putting a suction on your furnace
room. I believe what this person was trying to tell you is you could
put a negative pressure on your furnace room. This could indeed cause
carbon monoxide to build up in the furnace room and possibly the rest
of your house! This is very dangerous to you and your family. The
flame in your furnace is vented to the outside through some kind of
exhaust fan in the furnace. It is installed in such a way that it can
pull combustion air out of the furnace room and pass it through the
burner and then exhaust it to the outside. By putting a suction on
the furnace room to ventilate your work area you run the danger of
actually pulling that burner exhaust backwards into the furnace room
as your fume exhaust fan could fully or partially over power the
burner exhaust fan. The burner exhaust contains carbon monoxide and
you definitely don’t want to pull that back into your house. You need
to consult with a ventilation expert from your furnace company before
doing this.

James Binnion
James Binnion Metal Arts


There is good advice regarding the piping elbows, flex duct etc. in
other replies. Your concern about CO is legitimate. Any combustion
process uses oxygen. This can result in a vent / draft problem in an
enclosed space. When the furnace runs there needs to be some source
of fresh air to replace that consumed in the combustion (gas
furnace, not problem with electric or heat pumps). This wasn’t a
problem with the older, leaky houses. But newer, tighter houses can
have this problem. Many times there is a combustion air inlet near
the furnace to alow the room to breathe. If there is too much of a
suction (negative) when the furnace and exhaust fan run, it will
prevent the flue gases from venting properly. That is where the CO
and furnace damage happen. One way to handle this is to bring in as
much or a little more air as you are exhausting (e.g. 600cfm in, 400
cfm out). This will also help you in exhausting the fumes form your
work. Plan the intake so that it creates a flow past you and out the
exhaust. Don’t forget to include all sources of exhaust and
combustion such as driers and water heaters. You can test the air
pressure in your room by running all exhausts, heaters, and intake
fan, doors and windows all shut; then seeing if you have a flow in or
out the room when the door is barely openned. This will indicate if
your room is in a negative or positive. Ideally it should be slightly
negitve to the rest of the house but positive to the outside.

However most houses are at a negative with respect to outside and
this has become a problem with newer houses because of how tightly
sealed they are. There are now heat recovery ventilators on the
market to exchange heat between the exhaust and intake air for energy
efficency. Bottem line: make sure that, worst case, your flue gases
from the furnace etc. exhaust properly and that the fumes from your
work don’t go into the house. As to the effect on furnace life: fumes
from other things will corrode theheat exchanger in a furnace when
drawn in during combustion. Some examples I have seen: a furnace
where the softner salt was kept open next to the furnace, beauty
salons, and dry cleaners. All of these have had accererated failure
of the heat exchangers in a gas furnace. I hope this helps you to
have a safe work area.

Dan Wellman
25+ years in heating and air conditioning, 20+ in commerical work.