Degree of exhaust for vent system for soldering

A question - what is the best degree of exhaust for soldering?

Here’s the original question poised to me:

Second, we met with an engineer today about the metal studio. We’re
getting closer, Joy. What he needs to know is the quantity of gas in
the tanks we want to use. What would you recommend or suggest. What
is the cubic feet of gas in the tank. And it looks like we might be
able to keep the tanks in the room. There is a maximum amount of gas
in the code specs and he thinks this could work.

And third, could you direct me to a source for the venting hoods we
would want to have, and any recommendations. I know they should be
able to be regulated as to the degree of exhaust because, in my
understanding, soldering requires less draw, than lampworking. (I
recommended HVAC ductwork, for that is what I have).

I have been working with a non-profit organization that is trying to
setup a jewelry/lampworking studio and I’m getting questions I’m not
sure how to answer, but I’m the metalworking/jewelry consultant. I
can set upa jewelry lab for best efficiency and layout, but amount
of degree in exhaust has never arised for me. I’m still having
trouble finding out thecu. ft. capacity for a 5 tank (the big 5’
tanks) for I only use the B tanks.


Hi Joy,

I made an inexpensive and very efficient ventilation system for
soldering by using a bathroom ceiling style exhaust fan and some
4inch flexible aluminum ducting. What I did is just leave the fan
inside its cardboard box cut two 4" holes in the box, one for intake
and one for exhaust in the appropriate places. Then I used metal
stovepipe tape to attach the ducting, the exhaust goes out to
outside through a hole in the wall, and the intake goes to my
soldering station. The fan itself and its box are mounted to the
wall with small shelf brackets. I have the intake duct held over my
soldering board by one the tweezers of my third hand and I
installeda switch nearby so I can switch the fan on before and after
soldering. It’s really great with the flexible metal ducting I can
postion the intake directly over the piece I’m working on. I solder
a lot and I like to work veryclose to the flame and with this system
I never have that baked eyeballs feeling after many hours with my
face 6 or 8 inches from the flame. Also because the ducting is
flexible I can push my soldering station out of the way on mybench
when I’m not using it and the ducting goes with it. I hope this
helps. You can spend a lot on a ventilation sytem that will pull all
the air from the room but IMHO it’s probably better use a small
cheap fan that pulls less air but does so from directly over the
flame where it counts.

Thanks Dug for your info.

However, the non-profit educational school I am working with is in a
public building, so we are dealing with fire marshals. We have to
beef upthe existing vent in the room, beef up the insulation,
fireproof the walls, switch to an even thicker fire door and
framing. Therefore, we can’t just lump together a bunch of ductwork
and a fan to pull out the fumes. The fumes have to go out in a
separate vent pipe, from the basement room, through the ground
floor, through the garage before being vented out into the open
door. It’s gotten complicated.

All we want to do is set up soldering stations and lampworking
stations, and we can’t do anything till we deal with the room
itself. An engineer has already been hired and just need to know how
much degree of exhaust for vent system for soldering. That’s the
answer I cannot give. Mypersonal vent in my studio isn’t very
strong, but it’s adequate for my needs.

Frankly, it would be a lot cheaper to stick a fan in a window, but
sincewe have no windows, in a room in the middle of the ground
floor, and having 6 stories of people above the room, fire marshals
watching every move, we have to have a proper ventilation system
that is separate from the main building itsefl.

The engineer needs degree of exhaust for vent system for soldering
so wecan move on to planning the vent system.


Hi Dug,

That exhaust system of yours sounds excellent! May I ask approx what
diameter the ducting is? I’ve been trying to think of how to vent my
soldering area, & this sounds like a winner.

Any possibility of a photo of the system?

(This is my first post on the forum - been a long time lurker,
learnt heaps!- hopefully this works :slight_smile:


In my 50 years+ in the HVAC business I thought I had heard it all,
but every now and then someone surprises me with another harebrained
scheme about how they ventilated their premises. Just because the
fan works does not mean your room is being ventilated ADEQUATELY. In
the description of how you went about installing this imitation
Mickey Mouse ventilation system you make only one true statement ‘‘it
is cheap’’. In order to design a system that works and safeguards
your health a lot of factors need to be taken into consideration.
These can be found through ASHRAE and your state safety agencies as
well as the Internet. The gases created through soldering and brazing
are noxious and harmful to the respiratory system and the negative
effects of these may not show up until many years later.

The engineer needs degree of exhaust for vent system for soldering
so wecan move on to planning the vent system. 

There’s a book on this, hopefully Rio still sells it. It’s called
something like Ventilation Systems for the Jewelry Studio and it
tells you how much fresh air needs to come in to the room per hour,
or whatever. (It’s been a while since I read it.)

But I think it would give your engineer the answers he needs.



If you upset someone, they are just upset. If you upset the fire
department or OSHA, it becomes policy.

May I suggest that an alternate way of beginning this critical
project would be to obtainthe MSDS on each of the chemicals to be
used in the shop. Next, employan industrical hygenist, who will be
able to determine all appropriatechemical exposure limit(s) based on
all applicable factors - this is a complicated undertaking. They’ll
also be able to calculate usage levels, air exchange requirements,
etc. While you’re at it, you should ask for a noise study to also
determine TWA and other limits (there are very likely some machines
whose short term noise generation will need to be addressed).Other
considerations are the GHS that everyone will need to be trained in
by December of this year, and the records thereto, etc. etc.

Theonly “cheap” ways out with a limited budget I can think of
might be to:

  1. Contact “good” OSHA (not the one that fines you). Many states
    have an OSHA consulting unit that will provide advice of a
    professional nature. So long as several conditions are met it’s a no
    harm, no foulrelationship. I’ve used them before, they were great.
    They’ll tell you all the ground rules beforehand.

  2. Your project is complicated enough that it would be a challenging
    and valuable project for a person in an advanced college industrial
    hygene or safety program - especially one who plans to earn the CSP
    once out of college. This would get their “project” out of the way
    and documented.

  3. Contact a safety organization (for instance, the American Society
    of Safety Engineers) and seek their guidance for programs in your
    area. Really, it’s complicated enough that you may be able to find
    someone to do it for free for their portfolio.

Good luck -


You might be an hvac specialist but you have no idea how well my
ventilation fan works based on a simple description. Besides being
condescending and insulting you are basing your response on the
supposition that just because something is cheap and home made it
does not work. I have used large hood type exhaust fans in other
shops and studios. Actually itseems to work better have the intake
directly over the flame where it can pull the heat and gasses
efficiently from the area where they are being produced, rather than
pulling all the air from the room but allowing the fumes to pass
over my face on their way up to the hood. I use my "mickey mouse"
system for many hours almost every day and I have never once had
that burnt face feeling I used to get when using a hood. All the
heat and gasses go straight into the intake and away from my face.
If you disagree because you are an “expert” that’s fine but I know
what works in practice in my own studio.

All the best…

Hi Joy

if the engineer does not know the specs, you got the wrong one for
the job.

You need an air conditioning engineer. It sounds like the fumes have
a long way to travel and a powerful fan would be needed. Also the
bends in the pipe will slow down airflow. Also if you use the
flexible ducting it slows down air flow and traps dust.

How noisy/annoying will the fan get? You will need kill switches for
the fan in case a fire starts. One on the soldering bench and one on
the exit door.

How will you store chemicals and will there be fumes from them?

How will you get fresh air into the basement? It is good to remove
toxic fumes but you need clean air coming in.

These are questions an air conditioning engineer can answer for you
and tell you how to get the job done.

As you are building a metal workshop the air con. engineer can
design the fume hood and it can be made out of galvanised tin with
very basic tools like drills and rivets and silastic sealer. The
metal dealer would cut your pattern and you would just have to
rivet/bolt the sections together and bolt to the wall. And save some
money for metals and stones.

It will be difficult to set up a workshop in a basement, but hey
I’ve seen NCIS that guy builds boats in his basement.

Now we on Orchid can’t wait to see what the students make, they
should all join Orchid

All the best any questions, I teach jewellery at a not for profit
school, email me off line for any info you need.

Xtines Jewels

We used beehive roof ventilation which would suck up soda cracker
from 18 inches below opening

Why not a designated soldering station with fume extractor? I use a
Quatro and is only a two station but they have them up to eight

Certified 99.97% HEPA rating on .3 microns. Zero bypass for chemical

It is a three part filter and works extremely well. They have
station hoods with the filters built in without any venting required.
Be sure to stress to the FD it is a fume extractor and not a filter.

I also use a Guardian Air Scrubber for general usage so no
fumes/smells enter the house. I would never hear the end of it if a
hint of burn out wax smell entered the house! I have a 115 year old
home with two 275 gallon oil tanks in the basement. Over the last
60-70 years of oil use, (coal previously) there were overflows. I
removed soil, scrubbed, anything you could imagine as I hated the
smell. I ran the air scrubber 24/7 for two weeks and there is zero
smell now. I don’t know how it works.

I would contact Quatro for certification to present to the fire
department prior to purchase or engineering fees. Otto Frei, Stuller
and Rio Grande carry them. Andy at Stuller or a tech at the others
will guide you in obtaining certs needed and probably get quicker
results from Quatro than you or I. A simple hood over work stations
would capture almost everything if not all and route it to the
filter. Another benefit is they are portable should you change
location. Being on the ground floor you may want to test for radon as
well. If you are venting out (window fan) and not venting in, you may
be drawing in radon from the foundation or basement. Venting raw
unfiltered air to the outside may run afoul of the EPA which is much
stricter and powerful than the fire department. Body shops & auto
painters have much more elaborate equipment than us. An HVAC tech
will have access to all of this and better. Dentists use the same
equipment and have more inspections than us.

Good luck


Tough one…

First you are not looking for soldering stations exhaust systems Only
Jewelers call it soldering. The correct term is Brazing. Soldering
(In an industrial engineering sense) uses much lower temperatures and
generally substances that create less toxic smoke than brazing), so
if you are talking with a non-jewelry person you need to use brazing
so that they will be looking for the correct equipment.

For brazing stations (Lampworking stations can be considered brazing
stations because the amount of heat and toxic fumes liberated are
the same or less) should have a professionally designed and certified
extractor. That will tell you what sixe exhaust piping and the CFM
that has to be exhausted / made up).

That is the only way to be 100% sure that the “Cover my a$$ and
everyone else’s within 100 miles” OSHA inspector can be held at bay.
The worst part about them is that while you may successfully pass 3
inspections then all of a sudden there is a new inspector that
decides that he wants more cover than you have. Ahhh the pleasure of
dealing with Government inspectors who are always 1000 times worse
when it is a public building and seem to enjoy spending the public’s

One thing that most people overlook is what goes out has to be
replaced, so not only do you need to exhaust air you need makeup or
replacement air. If you are in a northern state (yes I know to
anyone in Texas and Florida, as far as they are concerned we are all
in frigid northern states) you may want to consider using a
flameproof chem lab fume workstation with the makeup air directly
injected into the work area to avoid exorbitant heating costs. Since
these are designed and certified to keep very close to 100% of the
fumes inside / exhausted to outside you would have the needed cover
for inspectors…

You really need a professional in the air handling equipment design
to do the necessary calculations.

Just some thoughts

There are a lot of considerations in constructing a good vent
system. I can say that my experience has shown that pulling the air
with an exhaust fan is preferable to pushing it through the ducts.
There is less chance for the contaminated air returning to the room
through any leaks in the duct connections.


I’ve gotten a lot of answers from both you on Ganoksin and Facebook
Metalsmiths 2:0. I’ve turned all the answers I’ve been given over to
the Education coordinator, and she’ll have to find the right HVAC

My job is making jewelry/metal objects, and I teach jewelrymaking,
so I’ve been in many studios/labs, and it’s interesting to see how
each school or lab has their own setup. My own vent is ok - not
great but it works for my brazing/gas welding needs.

I think we have talked enough about this, for I get the feeling I’m
coming across as a newbie, which I’m not, having spent almost 30
years in this field. I’m getting tired of having to compensate for
lousy facilities, needy students and just trying to do my job. I am
not trained in electrical or HVAC so that’s why I had to go out and
ask, for that’s not myjob. I can do plumbing, but that’s as far as
I’ll go.

Here’s the final kicker - not only the new jewelry lab had to have
vents, it also is going to be a lampworking studio as well as fused
glass. The one thing that gets me mad is that the organization
bought this huge kiln for fused glass, and it’s the wrong wiring,
wrong transformer, wrong elements. I wonder what was that glass
artist was thinking when she told the organization to get that
particular kiln. For a $1800 kiln, it’s going to cost up to 4 grands
just to redo the wiring, elements, transformer and the wiring in the
room. I’m going to have to make a big stink at the next Board of
Trustees meeting for it makes no sense. Thank god I don’t do fused
glass! That kiln has taken up valuable floor space that we can’t do
anything about.