Explosion proof fan thats isnt LOUD

gumby420 · Aug 24, 2016

Ok so i need an explosion proof fan for my new room. the only one thats been recommended to me is the allegro 20" blower. the only problem is that thing is LOUD!!! they were telling me they have to wear ear plugs in their lab, not exaggerating, im not trying to do that. i dont mind some noise, but that is insane.
any suggestions on a explosion proof fan that is not insanely loud? our room is 2800 cubic feet.

gumby420 · Aug 29, 2016

nothin...? haha i really dont want to have to wear earplugs in my lab

frog357 · Nov 28, 2016

Were you able to come up with anything on your own? I am curious if there is a recommended number of air exchanges per minute or whatever is used.

easystephen · Nov 28, 2016

Why don't you mount the blower on the roof? I can move 3000 CFM in my lab and it's whisper quiet. How much air do you need to move?

frog357 · Nov 28, 2016

When designing a ventilation system for a lab, do you place your blast proof fan in the room to push the air or do you place it at the end of the vent to pull? As I understand it, we want to allow air in from the roof and remove it from the floor. How we accomplish that is what I am seeking. I read to exchange the air 6 to 12 times per hour. (every 5 to 10 minutes).

Gray Wolf · Nov 28, 2016

An axle flow fan gets you the most free air, but won't tolerate much static pressure, and as you note, is loud.

A centrifugal fan will give you both the static pressure and quieter running.

gaiusmarius · Nov 28, 2016

interesting how it's upside down for labs, intake on high and exhaust down low. although i have read about exhaust hubs too for labs. anyway, with enough ducting and some over sizing so you can run it at a third of it's normal speed and you have a whisper quite ventilation.

Gray Wolf · Nov 29, 2016

gaiusmarius said:
interesting how it's upside down for labs, intake on high and exhaust down low. although i have read about exhaust hubs too for labs. anyway, with enough ducting and some over sizing so you can run it at a third of it's normal speed and you have a whisper quite ventilation.

Good point! A big slow fan is typically quieter than a little one screaming at maximum performance, as well as being more efficient.

Larger ducts have less total (TP) and static (SP) pressure at the same flows, than smaller ones.

Fan performance varies by design, but general fan laws are:

CFM varies directly as fan speed.
TP and SP varies as the square of fan speed.
HP varies as the cube of the fan speed.

There are minimum velocities that are recommended by the American Conference of Governmental Industrial Hygienist for both capture and transport. In table 4.1 of Industrial Ventilation, they list capture for a solvent released at low velocity into moderately still air, as 100 to 200 surface feet.

In a well designed room, without disturbing turbulence and cross air currents, 100 surface feet works, and what I typically use.

Table 4.2 gives design transport velocities for smoke and vapor as 1000/1200 fpm, and VS-604-5-6 provide their recommendations for spray paint booths. Note that with butane, the exhaust plenum needs to collect the vapors at floor level, rather than high as shown in the spray booth design.

gumby420 · Nov 29, 2016

ive been riding dirty an running with out one, luckily no leaks so far. this is the one ive been told to get and is the last thing on my to do check list ...http://www.allegrosafety.com/asp/product_detail.aspx?prodID=396

Gray Wolf · Nov 29, 2016

gumby420 said:
ive been riding dirty an running with out one, luckily no leaks so far. this is the one ive been told to get and is the last thing on my to do check list ...http://www.allegrosafety.com/asp/product_detail.aspx?prodID=396

That's a good example of a hot rod axle flow, designed for maximum output and portability. With hoses, that is what we typically used to vent fumes and smoke from industrial projects during construction or following accidents.

Loud, but effective and handy.

Much quieter would be a squirrel cage (centrifugal) fan, with a NEMA 7 motor mounted on the side, sitting remotely at the end of a duct.

montroller · Nov 29, 2016

Has anyone tried the centrifugal fans from greenheck? The cw/cwb models have a motor on the outside and they have models that easily mount to the roof. The only thing is the catalog says they offer explosion resistant casing for the motor and I'm not sure that's actually good enough. Can anyone offer insight?

live resin · Nov 29, 2016

Slightly off topic but has anyone experimented with closed ventilation systems using gas phase chemisorption using products from someone like Purafil?

How do you maintain a constant temp in the lab when your makeup air is freezing cold in the winter, even if only for operator comfort?

Pangea · Nov 29, 2016

I'll second that question, I dont loop from mid to late oct - april, to cold.

Jonny Lan · Nov 29, 2016

do inline fans explode? or are we talking about something else?

Old Gold · Nov 29, 2016

Pangea said:
I'll second that question, I dont loop from mid to late oct - april, to cold.

Whaaaaaat, I've looped in the snow. I loved it.
A pot full of gold is all the more gold with miles of white backdrop...

To answer the question above - simply put - it gets expensive.
I would think you'd have to take warm air from a very large heated space next door (or above).

easystephen · Nov 29, 2016

You can get the makeup air, conditioned. It's a whole separate HVAC system so it' pretty expensive.

live resin · Nov 30, 2016

Yea trying to avoid the whole expensive part that equation. The google machine mostly told me that conventional air scrubbing techniques (like Purafil chemisorption media) are not that effective with dilute concentrations (1000 ppm or less) of C3-C4 hydrocarbons.

However, from http://www.tandfonline.com/doi/pdf/10.1080/08940630.1987.10466344.

"Soil beds or soil biofilter sorbent beds naturally containing a high population of decomposer microorganisms, remove many gases effectively and inexpensively and might also scrub propane from waste air. Soils adsorb and decompose hydrocarbons from anthropogenic sources and from the atmosphere."

"The adsorption affinity increases exponentially with molecular weight of the hydrocarbons. Soils biodegrade n-alkanes faster than branched and aromatic hydrocarbons. Since the sorption capacity of soils for gases is relatively low, the feasibility of soil beds to scrub propane depends on the rate at which microbes decompose the propane and thereby regenerate the sorption capacity."

"Both laboratory and field tests indicated that soil beds (soil biofilters) successfully remove propane from waste air. The best bed removed about 95 percent of propane from air containing about 1 percent propane. Removal efficiency decreases to about 80 percent when soil bed temperatures near freezing. The removal efficiency also decreases in very dry soils and at soil pH < 6."

Does anyone know of any company producing smaller scale soil beds filters (not industrial size)?

Jellyfish · Nov 30, 2016

Jonny Lan said:
do inline fans explode? or are we talking about something else?

I know, right? I'm reading this thread, and nobody's saying the obvious thing- what the fuck you mean, "explosion proof fan"? They're pretty much all explosion proof as far as I know.

I'm laughing thinking about going into a store and asking for an explosion proof fan. wtf are you talking about, OP? :laughing:

montroller · Nov 30, 2016

Ideally your fan isn't exploding :laughing:

We are talking about a fan that is rated to run in potentially explosive environments... like if there was a leak in your system and you wanted to safely exhaust the gas polluted air from your work space.

Old Gold · Nov 30, 2016

Haha it deals mostly with how electrical components and the motor are housed. They are gasketed and enclosed to withstand high temperatures and high pressures. As to not provide a source of spark in the event of a leak or even an already ignited fire.

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