Standing particles in air will not dissipate with current air moving equipment

[AirMD]

Hello all, I am an air balancing technician and am working at a farm machinery fabrication plant right now. They are having problems with a severe negative pressure within the building as well as the smoke and particles from grinding and welding are not leaving the building with the current air moving equipment. I am trying to convince them a full air survey of all equipment that has an effect on pressurization or air changes is definetly the first step in this situation. Without any actual numbers to go off of my guess would be adding one or two HRV's to increase air changes per hour and installing a mua to offset the negative pressure would be the best way to start dissipatiing the standing particles in the air and to relieve the negative pressure. Any input would be greatly appreciated in regards to this matter.

 

[DRWeig]

Put this in Google:

handbook of industrial ventilation

Lots of resources there.

Best to you,

Goober Dave

Haven't see the forum policies? Do so now: Forum Policies

 

[cloa]

http://www.eng-tips.com/threadminder.cfm?pid=403

HAV forum best place for such a question

 

[tomwalz]

So they don't want to spend a lot of money on a survery? All too common an attitude in my consulting experience.

Can you do something easy and simple to demonstrate the need. It sounds as though you want positive pressure in the building. Can you increase the air intake by some means, see what that does to the inside pressure and calculate from there.

I suppose this is Iowa in the middle of winter and the last thing they want is more cold air.

Filter and recycle exisitng plant air instead of exhausting it.





Thomas J. Walz
Carbide Processors, Inc.

http://www.carbideprocessors.com

Good engineering starts with a Grainger Catalog.

 

[TheTick]

questions:

1.) How much air should the air handlers be moving?
2.) How much is moving?

 

[AirMD]

Hello, thx for your reponses. Im not sure how much air the plant is moving or should be moving right now. thay is why im trying to push for the survey.

 

[Tmoose]

The high negative sounds like the present HVAC or processes are set up incorrectly.

Welding fumes would require an expensive setup, but a dust and smoke collector with inlets close to dirty manufacturing areas, filtering and then returning the cleaned air to the occupied space would reduce energy losses and not be overcome by negative building pressure.

 

[zekeman]

Are there multiple exhausts, each at the designated function or are there scattered exhausts?
And how do they measure inside air quality?

If localized, then from Tomwaltz' filtering idea , you can cheaply demonstrate a reduction with filtering one major source without the loss of heat.
If not localized, you can still do it at one of the larger exhaust stations.

Cost would be some ductwork and a circulation fan, surely not enough to disturb the company's bottom line.

 

[zekeman]

Correction:

Cost would be a filter and some ductwork , maybe no new fan,
a very modest cost

 

[AirMD]

it is a plant of about 100000 square feet so to make an impact on the huge negative pressurization they are having it will take a fairly substantial increase in make up air volume to offset it. there are several different kinds of exhausts present in the building including filter/recirc systems in the robotic welding booths. They have 4-5 dust collection systems as well as general exhaust, snorkel exhausts and table exhausts. I think the only way for me to properly diagnose what problems are present in different locations around the buildings is by convincing them a full air survey is absolutely necessary. to add more difficulty the plant is divided between 3 buildings with adjoining corridors with pressures differing from building to building. but consistently negative

 

[tomwalz]

Heat Recovery Ventialtion and
Make Up Air

I reread your original post a couple times and, to me, it still sounds like a really long, expensive project. I don’t know if it would be or not. It just sounds to me like you want to measure the effect of everything including freight doors, man doors and every piece of equipment in the plant that moves air.

I think I might’ve started by telling them that, before I started spending money, I wanted to see what they had and what shape it was in. Now I think this is what you really meant but it sounds a lot less expensive my way.

We are in the process of our annual furnace tune up where they all get cleaned, parts replaced as needed and everything is brought back to spec.

When we did this last year we found that one of the summer exhaust vents with staying open all winter. This was a 3’ x 3’ square vent in the middle of the ceiling that people just forgot was there. Closing that vent was real low cost solution with a payback meaured in days, if not hours.


Thomas J. Walz
Carbide Processors, Inc.

http://www.carbideprocessors.com

Good engineering starts with a Grainger Catalog.

 

[chicopee]

I don't know how the air removing equipment is built so I am assuming that there is no ventilating hoods over the welding areas nor air scoops around the grinding equipment. I am assuming that you have exhaust ducts over the welding area and grinding equipement, however, the air flow thru these ducts is in reverse due to the high negative pressure within the building. I would say that you need more powerful exhaust blowers for the weding areas and grinding equipment to overcome the negative pressure within the building. Also have ventilating hoods and air scoops to assis in the removal of the pollutants.