DIY fume extractor... vent cover on down pipe?

[Yamhon]

When putting together a DIY fume extractor using an inline or axial fan do people feel there is any benefit to using a vent cover such as this one on Amazon on the down pipe where the fumes enter the ducting?

https://www.amazon.co.uk/Hon-Guan-S...ords=150mm+metal+inlet&qid=1576610683&sr=8-11

I'm thinking it may add stability to the open ducting and maybe make the system more efficient, and it will probably improve the look of such a system.

 

[rtcosic]

It will reduce the flow rate and increase noise.

Only useful if you have multiple inlets and you need to adjust free cross sectional area to balance flowrates.

Otherwise aesthetics only.

 

[Yamhon]

It will reduce the flow rate and increase noise.

Only useful if you have multiple inlets and you need to adjust free cross sectional area to balance flowrates.

Otherwise aesthetics only.

Thanks for that.

Maybe I'll just use something like this then?

https://www.amazon.co.uk/METAL-Flan...ds=150mm+ducting+flange&qid=1576612965&sr=8-6

 

[mtt.tr]

Parm is probably best to ask, he breaths ventilation.

 

[Parm]

Any opening, capture hood as they are known in the trade MUST be open and without any impedance

Putting that discharge cowl over capture hood will reduce the performance to such a point that it will render the system mostly useless

Have a look at what you will have seen at the college or perhaps what you may have seen in your books o give you an idea then emulate that

Edit: if you want I can scan some diagrams for you from the bible of industrial ventilation and process control. It’s got all the data, specification, calculations and other stuff that you can shake a stick at.

 

[Yamhon]

Parm is probably best to ask, he breaths ventilation.

While I welcome input; me and Parm are not always on speaking terms lol.

 

[Parm]

While I welcome input; me and Parm are not always on speaking terms lol.

Well to be correct, we’ve never actually spoken. All coms thro keyboard

 

[Yamhon]

Any opening, capture hood as they are known in the trade MUST be open and without any impedance

Putting that discharge cowl over capture hood will reduce the performance to such a point that it will render the system mostly useless

Have a look at what you will have seen at the college or perhaps what you may have seen in your books o give you an idea then emulate that

Thanks for the heads up. I got inspiration from YouTube, quite a few people have done a DIY version of those portable fume extractors for much less money.

I've got the go ahead to set one up in my parents garage (as I live in a flat); prevailing wind comes around the house and straight into the garage, so rather than fight against that I'm thinking to install a fan on the rear of the garage wall high up to pull the fumes out of the back off the property perimeter. From that I plan to use semi-rigid metal ducting 150mm diameter across the roof supports above head height to approx the center of the garage where I'm likely to be doing any welding, and leaving enough slack in that so I can pull it down and direct it a little. The fan I've got my eye on on Amazon just as blue, brown and cpc wires so I thought I'd just wire that into a plug, we have enough plugs to leave it plugged in and it can be turned on and off where it plugs in.

Only other thing I'm hesitant on is if I should put insect/rodent mesh on the outside of the fan outlet, feels like a good idea - more interested in stopping a wasp nest, as mice will find easier ways in anyway, although I wouldn't want it to reduce the airflow, which I have a feeling it will do.

 

[Yamhon]

This is where I got tonight's inspiration from.

 

[Parm]

Thanks for the heads up. I got inspiration from YouTube, quite a few people have done a DIY version of those portable fume extractors for much less money.

I've got the go ahead to set one up in my parents garage (as I live in a flat); prevailing wind comes around the house and straight into the garage, so rather than fight against that I'm thinking to install a fan on the rear of the garage wall high up to pull the fumes out of the back off the property perimeter. From that I plan to use semi-rigid metal ducting 150mm diameter across the roof supports above head height to approx the center of the garage where I'm likely to be doing any welding, and leaving enough slack in that so I can pull it down and direct it a little. The fan I've got my eye on on Amazon just as blue, brown and cpc wires so I thought I'd just wire that into a plug, we have enough plugs to leave it plugged in and it can be turned on and off where it plugs in.

Only other thing I'm hesitant on is if I should put insect/rodent mesh on the outside of the fan outlet, feels like a good idea - more interested in stopping a wasp nest, as mice will find easier ways in anyway, although I wouldn't want it to reduce the airflow, which I have a feeling it will do.

Hang on. Just yet. Don’t spend any money or buy anything just yet. When I’m sat at my desk Tommorow I’ll send you some stuff that you may find useful. YouTube is ok but doesn’t alway give the right info

 

[Parm]

This is where I got tonight's inspiration from.

Thevducting etc looks good and just the ticket. You’ll need a man sized fan for that sort of set up

And that “thing” in the hood is a non non. It isn’t acceptable here

 

[Shedendman]

https://www.ebay.co.uk/itm/Stealth-...hash=item25fcea2700:m:mvkhBJqo1DTdwb_fShrNvWA
Cheaper less hassle
Other options are available

 

[Yamhon]

Thevducting etc looks good and just the ticket. You’ll need a man sized fan for that sort of set up

And that “thing” in the hood is a non non. It isn’t acceptable here

This is the fan I'm interested in; I recall somewhere saying that axial fans are more efficient than inline fans, although I have no idea if it'll be up to the job.

https://www.amazon.co.uk/dp/B07R7LP...olid=2I0W386Z7WA7S&psc=1&ref_=lv_ov_lig_dp_it

I'm spent up until new year, but identifying what I need ahead of time will help me keep things on track and not blow my budget on other random stuff.

 

[Shedendman]

What if you cant weld over the spot where the duct is,like have to weld elsewhere for some reason,how you going to move nellys trunk then?

 

[Yamhon]

https://www.ebay.co.uk/itm/Stealth-...hash=item25fcea2700:m:mvkhBJqo1DTdwb_fShrNvWA
Cheaper less hassle
Other options are available

Have the same one :-)

Shortly going to attempt to cut down my big welding table so I can keep a smaller one in the garage and practice there... would ideally be able to at least shut the garage door half way so I get less cold in there over winter. I've only tacked stuff up so far with the respirator on and the door shut and it gets bad fume wise pretty quick without any real ventilation at all.

Thinking fume extraction plus 1 or 2 welding curtains in front of the open door might make it comfortable enough to practice a lot more when the weather is poor or just cold out.

 

[Parm]

https://www.ebay.co.uk/itm/Stealth-...hash=item25fcea2700:m:mvkhBJqo1DTdwb_fShrNvWA
Cheaper less hassle
Other options are available

Mmmmmm

 

[Yamhon]

What if you cant weld over the spot where the duct is,like have to weld elsewhere for some reason,how you going to move nellys trunk then?

Move the ducting or move the table/workpiece, if I can't do either I'll leave the door open and wear a respirator.

 

[Shedendman]

Weight up the costs with buying a top notch breathing app/mask to fitting duct/fans whatever,me,mask all the way

 

[The_Yellow_Ardvark]

What's wrong with buying a decent face mask and power pack?

That's what we used to use when I did Lorry loader cranes.

 

[Shedendman]

would ideally be able to at least shut the garage door half way so I get less cold in there over winter.

I always was lead to believe the yorkshire cold didnt give a hoot if a door was open,half open,or fully shut,you'll still be cold