Small Warehouse Ventilation Requirements 1

[TrippL]

I am trying to find out the ventilation requirements for a small warehouse made up of a 1500 s.f. main area and four smaller 500 s.f. areas. The smaller areas are separated by 2-hour fire walls. The ceiling height for all the spaces is 20 ft. There is no hazardous storage in any of the areas. There is only heating (electric unit heaters) in these spaces.

I do not have a copy of ACGIH's Industrial Ventilation Manual. If anyone could help me out I would appreciate it.

 

[trashcanman]

See ASHRAE 62.1

 

[TrippL]

ASHRAE 62.1 states that the Outdoor Air requirement for Warehouse is 0.06 CFM/SF. I think this is too low. Do you or anyone have other criteria that could assist me?

 

[317069]

0.06 cfm/sq.ft is the minimum, you could go over with any rate, But
your area: 1500+(4*500)=3500 sq.ft
Ashrae rate: 3500*0.06 = 210 cfm
210*60= 12600 cubic feet per hour
12600*(3500*20)= 0.18 air change per hour
it is ok for this kind of building

 

[TrippL]

Thanks for the info, but I'm looking at a Greenheck Technical guide (TI/101-02) that states a warehouse should have 3-10 minutes per air change, using the lower number (3 min) for more severe conditions and higher number (10 min) for less severe conditions. I judge this facility and location to have moderate conditions so I'm going to use 6.5 minutes per air change for each of the spaces. This gives me 4,615 cfm for the 1500 sf space and 1,538 cfm for the 500 sf spaces. This seems more inline with what I'm looking for. Loren-Cook's engineering cookbook has similar numbers. What do you guys think? See any issues with this approach?

 

[317069]

Do you mean that you are going to provide 4615 cfm of the outside air to the 1500 sq.ft space

 

[TrippL]

Yes. I know that is a lot of air but that is what I'm getting from the Greenheck guide.

 

[317069]

What about your own judgement,
You are mixing between outside air requirement as mentioned in ASHRAE 62.
(0.06 cfm/sq.ft) and the total cfm running in duct system,
Greenheck table suggest the cfm rate in your duct system not the outside fresh air rate.

 

[TrippL]

There is no duct system. Just sidewall exhaust fans and intake louvers.

 

[317069]

Then you do not need to use this table

 

[TrippL]

Why would this table not be applicable?

 

[317069]

it is applicable and you could use it if you want but it give from 6 to 20 air change per hour which would cost for heating in winter, you could go with 1 to 2 air change per hour that would give good ventilation and save on operation

 

[ProcessHVAC]

0.18 ACH is more than enough for this application unless you have any chemicals, contaminants etc.

 

[dynamo78]

I think there is confusion here, Ventilation requirement according to ASHRAE 62 is used in conjunction with the cooling load and not ventilation alone,it is the amount outdoor air required for acceptable indoor quality, to control CO2 and other contaminants.
@Trippl, What you need is the ACH (air changes /24 hour). Based on my experience, which may not be applicable now but I am sure still the same logic applies. For a electrical transformer room the ACH is 12- 15.any input on your surveillance of the sight? is it equipment oriented that heat must be removed? chemical that you just dont want air to be stagnant or toxic that you must maintain the LEL? In your case, assuming you need 8-10 ACH,@ 10 ACH, you CFM will be 486.CFM.

Hope that helps in a way.

Its been a while since I last worked in HVAC in the middle east and now my career is leading me to it again.

Feati

 

[willard3]

You need to hire an Engineer familiar with ventilation or talk to one in your office.

 

[TrippL]

Thanks everyone for your input. After discussing with numerous engineers familiar with ventilation I came to 4 ACH per space. This will provide adequate ventilation for the spaces and remove some of the heat in the summer months. The site is located in Charleston, SC so it gets very warm in the summer months. If anyone has any questions or comments let me know. Again, thank you for the helpful responses.

 

[edenriquez0601]

317069

0.06 cfm/sq.ft is the minimum, you could go over with any rate, But
your area: 1500+(4*500)=3500 sq.ft
Ashrae rate: 3500*0.06 = 210 cfm
210*60= 12600 cubic feet per hour
12600*(3500*20)= 0.18 air change per hour
it is ok for this kind of building

where did you get the 20?
0.06 cfm/sq.ft is the standard as per ashrae?
im from the philippines and i want to learn im not a mechanical but
i do understand some computation. im a saleman of exhaust fan but in my company there
is no mechanical engineer to estimate the exhaust.can you help me?

thank you in advance

edenriquez0601

 

[chicopee]

My estimation is more in line with dynamo78's 486 CFM.

 

[cry22]

OK TRIPPL

first please state your location and intended use next time,
you are trying to ventilate a warehouse in summer months to keep it from getting too hot in there. I would use actually 10 ACH, not just 4 ACH, reason, the difference in cost between 4 and 10 ACH for wall mounted exhaust fan in almost nothing

BUT, let me tell you that you will need 5 FANS and Five outdoor sir intakes. You seem to provide just one fan for all your 5 spaces separated with fire dampers.

Code does not allow you to transfer air from one room to another (using a room as a plenum), so each of your fire rated rooms will require a dedicated fan with dedicated intake (they can be both roof mounted). Besides, you will avoid all the fire dampers.