flow performance test

[rookie37]

At work we have a metal shed that sits in full sun. We cut windows (no glass just open holes about 1 x 1 meter) in it to improve ventilation. However the holes had to have louvers in order to keep the rain out. Vermin was also a problem. wire mesh had to cover the 1x1 meter hole. The louvers also reinforced this mesh from wobbling as it is too frail to span 1 meter.

I think the design of these louvers is an overkill. While they do a wonderful gob keeping the rain out, they reduce the ventilation. I would like to remove every 2nd louver. This would increase ventilation but still be adequate to keep the rain out. I can model it in Inventor or 3d Autocad. How do I test the flow? I'd like a before my proposed modifications and after.

 

[willard3]

Get a velometer and measure the flow.

 

[Wilbur55]

There was apparently money to install louvers and mesh. Is there money to install a fan?

Or a roof turbine ventilator?

http://www.empirevent.com/vents_turbine-ventilators.html

I misunderstood your post on first reading. I think I now understand that you propose removing every second blade from each louver; not removing every second louver assembly, which would let the rain in half the locations.

Under what conditions would you test this modification? What outside air temperature and wind speed? Do you know how much airflow you had before the louvers were installed; how much there is now; how much you need?

What is the cost of items destroyed by excessive heat until a solution is implemented? What is the cost of engineering and management time to agonize over a solution to this problem? How much would it cost to remove every second blade from each louver?

What size fan would accomplish the needed airflow? How much would it cost to install the fan?

 

[rookie37]

Management has not allocated for me do research this. I'm doing this by stealth. I would like to show them on paper how they can greatly improve things without spending any money. (A top priority for them) It cost virtually nothing to drill out the pop rivet heads that keep the louvers in place. The moment that I say that it will cost anything, the answer will be no.

Does such software exist?

 

[Wilbur55]

Suggestion: Enjoy your weekend; don't worry about this.

Why do you think it is a problem that the louvers "reduce the ventilation?"

If your modified louvers let in any rain, then you will probably hear about it:

We didn't have this problem until Rookie37 cut up the louvers. Actually, he isn't the one who did it. I had to climb over boxes to remove the the blades; which, by the way, made the louvers ugly. I cut myself on the sharp edges of the removed blades, and on the mesh. Now I have to mop up the rain that his modified louvers let in; except where the water landed on boxes and ruined product.​

If no one is looking for a solution, they may not welcome one.

 

[rookie37]

If your modified louvers let in any rain, then you will probably hear about it

I'll take that risk. The product that risks rain damage is stale bread. We make thousands of loaves of fresh bread each day. We also get back hundreds of loaves that the stores didn't sell that's getting close to it's used by date. We take this stale bread and sell it to a company that adds it to animal food.

 

[Artisi]

Remove every second louver and extend the blade length on the remaining louvers - should fix the rain ingress.
What's the next problem - as any air flow restriction would be the result of the wire mesh - not the louvers.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[chicopee]

For ventilation to occur when the shed door is closed, you'll need two openings, one at the top of one wall and the second opening, on the lower portion of the opposite wall. To detected air flow,but not quantitively, do a smoke test, either with a cigar, cigarette or smoke test tube.

 

[dbill74]

For my 2 cents, ask your bosses for money to add more louvers. You risk more than just damaging stale bread by removing blades of the existing louvers without telling your bosses, you risk your job if they can't sell nearly stale bread to animal feed producers.

Since your stored product is bread, I am a little surprised you're not doing more to control the environment in the shed. I imagine the purpose of the ventilation is to increase the longevity of the bread; would not better temperature and humidity control increase the shelf life of the bread further?

 

[purewater1]

The flow and rain problems all depend on the size of the opening when it comes to the wire mesh - if you are using mesh with a large opening - obviously - more flow gets through the mesh, therefore effecting everything else. If you are using a finer mesh - something like the 40 x 40 wire mesh seen here ( Link )you may have better luck. The 40 x 40 means that there will be 40 wires, and 40 openings, in every inch of material - in other words, if you look at this thing by the foot - which most of us will in this case - you will have 40 x 12 (480) wires per linear foot of wire mesh - this is a lot of wires and will certainly effect the flow rate we previously had mentioned.

 

[rookie37]

I guess that I didn't explain it very well. Getting money from management for improvements is like trying to pull their teeth!

A fan, velometer, smoke test, or additional spinner vents on the roof are not an option

As you can see by the picture, the vent is a ridiculous design. The 'keep the rain out' aspect of it is quite an overkill

http://content.screencast.com/users...-5619-4cba-9f50-a0035ad6802a/shed louvers.jpg

Anyone can see that removing louvers would increase air flow. However I will like to give them numbers, data, or some type of simulated performance test on the computer.

 

[Artisi]

I would suggest if management are too tight (read stupid) to put a bit of money into "their" problem then bad luck, the problem remains and they need to live with it.
As for the louvres restricting flow - very unlikely however if the mesh is fine then it will certainly restrict any flow.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[chicopee]

All this attention for a shed. What do you store in it? a lawn mower and some gasoline perhaps or is it for something more crucial to the plant safety?

 

[Artisi]

Chicopee

Come on now, this is a very serious engineering problem and discussion, with the stored contents far more critical than a lawn mower and a can of fuel, it's stale bread (see earlier post from OP).

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[Wilbur55]

I asked before: "Why do you think it is a problem that the louvers 'reduce the ventilation?'"

Is the bread getting moldy because moisture can't get away?

Is it losing water weight because higher temperature in the shed is driving moisture out and selling the bread by the pound results in less revenue?

What problem needs to be solved?

 

[rookie37]

I'm not concerned for the stale bread, it's just so hot that working in there is torture. I'll just have to get use to the hot house. Anyway, you answered my question. There is no way to calculate the airflow on this without physically doing it with smoke or differential pressure.

I would suggest if management are too tight (read stupid) to put a bit of money into "their" problem then bad luck, the problem remains and they need to live with it.

That's the problem, they don't live with it. They live in an air condition mansion worth 2.3 squillion dollars

 

[Wilbur55]

Can the doors be modified so the top halves can be left open when it isn't raining?

Similar to this:

https://en.wikipedia.org/wiki/Dutch_door

 

[chicopee]

I,somehow, missed the stale bread storage; my apologies.

 

[macmet]

I believe there are methods you can use from ASHRAE that may allow you to calculate approximations for the air flow.

Are these louvers designed in house or are they engineered by a company who specializes in it? Maybe they can provide feedback on increased flow with removing every other blade.

I also think there is a lot of good feedback from the members already given.

 

[cry22]

remove the louvers, install wiremesh and rain hoods similar to RTU outside air intakes - imagine a gooseneck with just the beak (no neck).
You get 100% free area, no rain intake.