Orifice sizing
Orifice sizing
(OP)
Does anyone know who to size an orifice with the following parameters. What I am trying to find is the diameter of the orifice I need to have to drilled in a orifice plate in a swagelok fitting to allow 2 gpm flow with a .5 psig drop and the fluid is DI water. The value I came up with was 0.153 inches, but I am not very confident in this value.
flow rate - 2 gpm
tube size - 3/8"
Specific Gravity - 1
Beta - 0.4 to 0.6
Pressure drop across orifice - 0.5 psig
flow rate - 2 gpm
tube size - 3/8"
Specific Gravity - 1
Beta - 0.4 to 0.6
Pressure drop across orifice - 0.5 psig





RE: Orifice sizing
What is the actual ID of the tube? It will have an impact on the orifice sizing.
Just a note - pressure differentials are neither absolute nor gauge. You should specify your pressure drop as 0.5 psi and not 0.5 psig.
Katmar Software
Engineering & Risk Analysis Software
http://katmarsoftware.com
RE: Orifice sizing
What I am trying to maintain is a 2 gpm flow rate, but it does not have taps. This flow is through a 3/8" SS .065" wall thickness tubing and I was going to use a swagelok union with orifice inside the union to control the flow. That is why I am trying to figure out the diamter of the hole to drill in the orifice. The 0.5 psi was a value that I selected. I was trying to keep the pressure drop bewteen 0.5 and 1 psi, but the main variable I am trying to main tain is the beta around 0.4 to 0.6. To answwer you question I believe the ID of the tubing is 0.375" - 0.065" = 0.31".
The equation I used was the following.
d= diameter of orifice hole (?)
Q= flow rate (2gpm)
K= constant variable for flow through orifice (0.62)
H= Head across the orifice (1.155)
Pressure (psi) = (Head * Specific Gravity)/2.31
0.5 = (Head * 1)/2.31
Head = 1.155
d= (Q/19.63(K)(Hsqrt))sqrt
d= (2/19.63(0.62)(1.155 sqrt))sqrt
d= 0.153"
ID of tubing is 0.375" - .065" = 0.31"
Beta = 0.153/0.31 = 0.493
RE: Orifice sizing
Good luck,
Latexman
RE: Orifice sizing
Pressure (psi) = (Head * Specific Gravity)/2.31
3 = (Head * 1)/2.31
Head = 6.93
d= (Q/19.63(K)(Hsqrt))sqrt
d= (2/19.63(0.62)(6.93 sqrt))sqrt
d= 0.249"
My Beta would now be 0.806.
RE: Orifice sizing
However, I have some doubt, because you really did not answer or elaborate on katmar's question on permanent pressure drop in a way that makes me think you know enough about this subject to make it work right the first time. Plus, you use a K = 0.62 with a beta of about 0.8, and you never mention checking the Reynold's number. All these put together creates doubt in my mind. Does anyone else have this feeling?
Good luck,
Latexman
RE: Orifice sizing
Is the 0.5 psi pressure drop the permanent pressure drop (i.e. are you designing a restriction orifice) or is this a flow measuring orifice with close tapping points?
Yes, it will be a permanent pressure drop with a constant pressure supplied from a header that should be a consistent 45 psig from a pump. I am trying to design this as a restriction orifice and it will not be monitored for flow. There are nine other taps off the main header that are cooling other equipment that also have restriction orifices in them. I have a total of 34 restriction orifices in this system. There are 4 in a 3 inch line, 2 in a 1-1/2 inch line, 20 in a 1 inch line, and 8 in a 3/8 inch line. This tubing and piping are cooling bus bars and a chamber that is being heated by induction coil and they keep the coils and bus bar and associated power units and load matching stations at a desirable temperature. I hope this helps explain what I am trying to do.
I have all the other restriction orifices completed, but I was having a problem with these 3/8" tubing lines, because my software program does not go below 1/2" lines, so I needed to do it by hand.
Thanks for your help
RE: Orifice sizing
Good luck,
Latexman
RE: Orifice sizing
You have been very helpful and I appreciate it.
RE: Orifice sizing
Good luck,
Latexman
RE: Orifice sizing
RE: Orifice sizing
RE: Orifice sizing
RE: Orifice sizing
wfeldmann - sounds interesting. Are you in the design, construction or start-up phase? How long are the 3/4" supply and return mains? How long is each 3/8" supply and return branch?
Good luck,
Latexman
RE: Orifice sizing
RE: Orifice sizing
Good luck,
Latexman
RE: Orifice sizing
Good luck,
Latexman
RE: Orifice sizing
Another use is for slowing the air bleed rate on valves. For example, you find that your liquid esd valve is in water hammer and you need to slow the closing, just pop 1 or 2 in and the vent, the valve slows up. We kept several different Cv values of the disks around and used them as needed.
RE: Orifice sizing
What we are building is a plant to destroy stock piled chemical weapons in Richmond, KY. The plant will probably be operation in 3-5 years and operate for another 5 years after that. We expect to have one of our systems finished by this September so that they can start pouring the walls around it.
Thank you for all your help.
RE: Orifice sizing
Good luck,
Latexman