Hello, this is my first message to the forum.
I am doing some research on ORIFICE PLATES for a flow bench.
Tried an orifice on a SF 110 to make correlation with formulas presented by Dave
in this forum section.
The results didnīt agree with the calculations suggested by Dave.
I may missing some thing or doing wrong calculations or using wrong units.
So, I am asking help.
Will describe what I have doned.
Made a wood box measuring 10 x 10 x 10 inches with all faces closed except
a 5 in. holes at bottom and at top.
Fixed the box bottom at the SF110 working table with the
SF CALIBRATED ORIFICE at the top.
At the middle of the box, internally, had installed:
AN ORIFICE WITH D= 1.604 in. , that equals an area of : 2.022 sq. in.
To measure de DIFFERENTIAL PRESSURE -"DP" at this orifice plate had installed
- 1 pressure p/ups at 1 in. downstream and another 1 in. upstream of the plate and
- 1 pressure point close to the top SF orifice plate
With
10 in.H2O inlet pressure get:
SF CFM = 158
Top manometer : 10 in.H2O
D. P . = 8.6 in.H2O B]
Tried the
PTS Forum Excell formulas and found only :
102.3 CFM
For
DAVE`S formula found:
M1 = 10 in.H2O = 254 mm H2O
M2 = 8.6 = 218.4 mm H2O
To have the orifice target flow: 2.022 x 0.60 x 87.2 = 105,9 CFM
(87.2 is related to the venturi flow of 138 per sq in at 25 " transformed for 10")
So, square root of M2/M1= 0.927
Thus : 0.927 x 105.9 = 98.1 CFM !!??
SF 110 Flow : 158 CFM
Appreciate your comments and corrections on this experience .
Jorge