What I would like to know is whether centrifugal fans along the lines
Gingery describes might be suitable for building one's own fume hoods.
Naturally, the suitability of the fume hood depends on the application,
so part of the question is: What kinds of chemical experiments might
a fume hood based on such a fan be suitable for? For example, might it be
adequate for microscale organic labs?

In the past, I asked on sci.chem whether one could improvise a fume hood
by using a vacuum cleaner to exhaust the hood area. I was told that this
was not a good idea because combustible vapors (the solvents, e.g.) would
pass through the motor and maybe explode. I was told that instead one had
to use "explosion-proof" motors to pump the air.

Lindsay Publications publishes a book by David Gingery entitled, "How to
design and build centrifugal fans for the home shop". With the fans he
shows you how to build, the air doesn't go through the motor and, presumably,
the motor can be placed as far away from the fan as one wants.

What I would like to know is whether centrifugal fans along the lines
Gingery describes might be suitable for building one's own fume hoods.

Naturally, the suitability of the fume hood depends on the application,
so part of the question is: What kinds of chemical experiments might
a fume hood based on such a fan be suitable for? For example, might it be
adequate for microscale organic labs?

In the past, I asked on sci.chem whether one could improvise a fume hood
by using a vacuum cleaner to exhaust the hood area. I was told that this
was not a good idea because combustible vapors (the solvents, e.g.) would
pass through the motor and maybe explode. I was told that instead one had
to use "explosion-proof" motors to pump the air.

Lindsay Publications publishes a book by David Gingery entitled, "How to
design and build centrifugal fans for the home shop". With the fans he
shows you how to build, the air doesn't go through the motor and, presumably,
the motor can be placed as far away from the fan as one wants.

What I would like to know is whether centrifugal fans along the lines
Gingery describes might be suitable for building one's own fume hoods.
Naturally, the suitability of the fume hood depends on the application,
so part of the question is: What kinds of chemical experiments might
a fume hood based on such a fan be suitable for? For example, might it be
adequate for microscale organic labs?

Ignorantly,
Allan Adler
ara@zurich.ai.mit.edu

****************************************************************************
* *
* Disclaimer: I am a guest and *not* a member of the MIT Artificial *
* Intelligence Lab. My actions and comments do not reflect *
* in any way on MIT. Moreover, I am nowhere near the Boston *
* metropolitan area. *
* *
****************************************************************************

===
===<>In the past, I asked on sci.chem whether one could improvise a fume hood
===<>by using a vacuum cleaner to exhaust the hood area. I was told that this
===<>was not a good idea because combustible vapors (the solvents, e.g.) would
===<>pass through the motor and maybe explode. I was told that instead one had
===<>to use "explosion-proof" motors to pump the air.
===
===<>Lindsay Publications publishes a book by David Gingery entitled, "How to
===<>design and build centrifugal fans for the home shop". With the fans he
===<>shows you how to build, the air doesn't go through the motor and, presumably,
===<>the motor can be placed as far away from the fan as one wants.
===
===<>What I would like to know is whether centrifugal fans along the lines
===<>Gingery describes might be suitable for building one's own fume hoods.
===<>Naturally, the suitability of the fume hood depends on the application,
===<>so part of the question is: What kinds of chemical experiments might
===<>a fume hood based on such a fan be suitable for? For example, might it be
===<>adequate for microscale organic labs?
===
===<>Ignorantly,
===<>Allan Adler
===<>ara@zurich.ai.mit.edu
===
===<>****************************************************************************
===<>* *
===<>* Disclaimer: I am a guest and *not* a member of the MIT Artificial *
===<>* Intelligence Lab. My actions and comments do not reflect *
===<>* in any way on MIT. Moreover, I am nowhere near the Boston *
===<>* metropolitan area. *
===<>* *
===<>****************************************************************************

In the past, I asked on sci.chem whether one could improvise a fume hood
by using a vacuum cleaner to exhaust the hood area. I was told that this
was not a good idea because combustible vapors (the solvents, e.g.) would
pass through the motor and maybe explode. I was told that instead one had
to use "explosion-proof" motors to pump the air.

Lindsay Publications publishes a book by David Gingery entitled, "How to
design and build centrifugal fans for the home shop". With the fans he
shows you how to build, the air doesn't go through the motor and,
presumably,
the motor can be placed as far away from the fan as one wants.

What I would like to know is whether centrifugal fans along the lines
Gingery describes might be suitable for building one's own fume hoods.
Naturally, the suitability of the fume hood depends on the application,
so part of the question is: What kinds of chemical experiments might
a fume hood based on such a fan be suitable for? For example, might it be
adequate for microscale organic labs?

Ignorantly,
Allan Adler
ara@zurich.ai.mit.edu


****************************************************************************
*
*
* Disclaimer: I am a guest and *not* a member of the MIT Artificial
*
* Intelligence Lab. My actions and comments do not reflect
*
* in any way on MIT. Moreover, I am nowhere near the Boston
*
* metropolitan area.
*
*
*

****************************************************************************

In the past, I asked on sci.chem whether one could improvise a fume hood
by using a vacuum cleaner to exhaust the hood area. I was told that this
was not a good idea because combustible vapors (the solvents, e.g.) would
pass through the motor and maybe explode. I was told that instead one had
to use "explosion-proof" motors to pump the air.

On 24 Dec 2003 02:04:58 -0500, Allan Adler <ara@nestle.ai.mit.edu
wrote:


In the past, I asked on sci.chem whether one could improvise a fume hood
by using a vacuum cleaner to exhaust the hood area. I was told that this
was not a good idea because combustible vapors (the solvents, e.g.) would
pass through the motor and maybe explode. I was told that instead one had
to use "explosion-proof" motors to pump the air.



The fume hoods at the lab I work for are not explosion proof.
They use a squirrel cage fan attached directly to a motors shaft.

Use of solvents in the hood are such that the vapor concentration
doesn't reach flammable levels, let alone explosive.

Dave

All this talk about explosion proof motors and blowers makes me chuckle.

While "explosion proof" equipment is more resistant to causing an explosion,
as I understand it, the term more appropriately refers to the fact that WHEN
an explosion occurs, the device is more likely to contain the explosion, and
prevent sending shrapnel in every direction.

David A. Webb wrote:

On 24 Dec 2003 02:04:58 -0500, Allan Adler <ara@nestle.ai.mit.edu
wrote:

In the past, I asked on sci.chem whether one could improvise a fume hood
by using a vacuum cleaner to exhaust the hood area. I was told that this
was not a good idea because combustible vapors (the solvents, e.g.)
would
pass through the motor and maybe explode. I was told that instead one
had
to use "explosion-proof" motors to pump the air.

The fume hoods at the lab I work for are not explosion proof.
They use a squirrel cage fan attached directly to a motors shaft.

Use of solvents in the hood are such that the vapor concentration
doesn't reach flammable levels, let alone explosive.

Dave

Why would vapor have to pass "through the motor" anyway? Just hook up
the blower end to a pipe that intersects with the hood outlet. The
fumes will be sucked out, but still blown *away* from the motor.

In the past, I asked on sci.chem whether one could
improvise a fume hood by using a vacuum cleaner to
exhaust the hood area. I was told that this was not
a good idea because combustible vapors (the solvents,
e.g.) would pass through the motor and maybe explode.
I was told that instead one had to use "explosion-proof"
motors to pump the air.

Allan Adler wrote:


What I would like to know is whether centrifugal fans along the lines
Gingery describes might be suitable for building one's own fume hoods.

First you assume we're familiar with Gingerys book. Nope. Not this guy
in RCF.

What does he use to drive the fan, a shaft? If your in an
explosive atmosphere I'm not sure you would want to use a belt. May
build a static charge.

A fume hood should be explosion proof, capable of moving a high volume
of air at low pressure and most of all quiet. Vacuum cleaner blowers
are none of those things.

I would suggest a large salvaged furnace blower with a 3:1 belt drive
to a 1/2 HP TEFC 1725 RPM motor. Mount the motor away from the
ductwork and bond it to the fan bearings and duct work with some wire
to drain off any static charge from the belt. Running at 550 to 600
RPM on good isolated bearings the blower will move a lot of air and
make an acceptably quiet low rumble. Filters need to be placed before
the blower.



Allan Adler wrote:

In the past, I asked on sci.chem whether one could improvise a fume hood
by using a vacuum cleaner to exhaust the hood area. I was told that this
was not a good idea because combustible vapors (the solvents, e.g.)
would
pass through the motor and maybe explode. I was told that instead one
had
to use "explosion-proof" motors to pump the air.

Lindsay Publications publishes a book by David Gingery entitled, "How to
design and build centrifugal fans for the home shop". With the fans he
shows you how to build, the air doesn't go through the motor and,
presumably,
the motor can be placed as far away from the fan as one wants.

What I would like to know is whether centrifugal fans along the lines
Gingery describes might be suitable for building one's own fume hoods.
Naturally, the suitability of the fume hood depends on the application,
so part of the question is: What kinds of chemical experiments might
a fume hood based on such a fan be suitable for? For example, might
it be
adequate for microscale organic labs?

Ignorantly,
Allan Adler
ara@zurich.ai.mit.edu

****************************************************************************

*
*
* Disclaimer: I am a guest and *not* a member of the MIT
Artificial *
* Intelligence Lab. My actions and comments do not
reflect *
* in any way on MIT. Moreover, I am nowhere near the
Boston *
* metropolitan
area. *
*
*
****************************************************************************