Diffuser Plate Sizing 1

[valves4life]

Gentlemen (and Ladies)-

My question is fairly simple. I have a consultant that usually does this type of sizing, as I never do diffuser plate sizing. However, I am going on a sales call tomorrow and will not be able to get an answer from my consultant before then.

Anyway, the conditions I have are
8" Diffuser- (i.e. Plate with holes drilled into it)

Q=2000 gpm
P1= 100 psig
P2= 7 psig
Fd= .07
Cv= 159.4
Media= water @ ambient

I just need to know how to figure out the hole size for the plate. I usually have someone size this and come up with the specs but I need to speak with the customer tomorrow about hole size/particle size in media and etc and will not be able to get the answer before then.

If I haven't given enough info let me know and I will upload the Sizing data I have....

Thank you in advance for any help. And PS. I'm not trying to be spoon fed. If you could just point me in the right direction, I'll put in the work, I just don't know where to start/what equations to use.

 

[StoneCold]

When I do this type of thing I just divide the flow up into how many holes I want to drill. That gives me the flow per hole. Then I calculate the orfice size for that hole. If that size is something I am not happy with, I choose another number of holes and start over.
Then I will graphically layout the hole pattern to see if it works. (The holes are spaced far enough apart and they all fit inside the 8" pipe requirement)

You did not mention how thick the diffuser was or what it was made of?

Regards
StoneCold

 

[valves4life]

StoneCold-


Right, I figured that would be my route to coming up with overall flow.

I think I worded my question wrong-

How do I calculate the flow for the hole that I drill. I understand how to calculate total, once I have number of holes and layout, etc. But I just need to know how to calculate flow through one of the single holes I drill.

I know its pretty basic, but I'm not clear on how to do it...

 

[StoneCold]

Just look up CV calculators online.
Enter your parameters and that will give it to you easily.

Regards
StoneCold

 

[StoneCold]

valves4life
I ran the numbers and if you drill 100 holes then they need to be 0.295" if you drill 50 holes you need 0.41" holes.
I did not try to do the layout, that is rather time consuming.
Hope this helps you out enough to get through your meeting.

Regards
StoneCold

 

[valves4life]

Thank you so much.

I think I just needed it to be explained like that.

I get it now. I appreciate your time. Thanks Again

 

[valves4life]

Stone Cold-

I have one last stupid question. Cf, As a flow coefficient. This is not the same as Cv. From

http://www.efunda.com/formulae/fluids/calc_orifice_flowmeter.cfm#calc

it seems it is defined in texts or through experimentation. I'm unsure what it would be for a simple orifice. If I use the numbers you gave me and reverse solve, it seems you used about .79 for the Cf.

Does this number change based on different hole sizes and/or pipe diameters?

 

[StoneCold]

I used 0.82 for a thick walled orfice. Thickness greater than twice the hole diameter. If you can use a thinner plate then you would use 0.61 for a thinner orfice.

Regards
StoneCold