Dwyer instruments, inc – Dwyer OP User Manual
Page 4
DWYER INSTRUMENTS, INC.
Phone: 219/879-8000
www.dwyer-inst.com
P.O. BOX 373 • MICHIGAN CITY, INDIANA 46361, U.S.A.
Fax: 219/872-9057
e-mail: [email protected]
©Copyright 2009 Dwyer Instruments, Inc.
Printed in U.S.A. 7/09
FR# 443396-00 Rev. 1
If Reynolds number (R
n
) is not known, “C” can be estimated as
0.6015. For convenience other factors can be combined to form
constants as the equation is developed.
MAINTENANCE
After final installation of the Series OP Orifice Plate Flow Meter, no
routine maintenance is required. A periodic check of system
calibration is suggested. With the exception of gasket
replacement, these devices are not field repairable and should be
returned if repair is needed (field repair should not be attempted
and may void warranty). Be sure to include a brief description of
the problem plus any relevant application notes. Contact customer
service to receive a return goods authorization number before
shipping.
AIR AND GAS FLOW - CONCENTRIC BORE
SCFM BASE CONDITIONS 14.7 psia & 60°F
Conversion formula used to solve for flow rate based on plotting
changes in inlet pressure, temperature, and/or differential
pressure. This formula is designed for use as a “quick check”
reference only as the results may differ from calculation values due
to rounding, combining of variables, and making certain
assumptions in an effort to keep the formula as abbreviated as
possible. Equation source Flow Measurement Engineering
Handbook by Richard Miller.
Input new h/w as well as new pressures and/or
temperatures using the formula below:
Where:
5.9816= physical constant
d= bore in inches
D= Pide Inside Diameter (inches)
K= flow coefficient
Y= expansion factor
h/w= differential pressure (inches w/c)
P
L
= line pressure (psia)
T
L
= line temperature (°F)
T
b
= base temperature (°F)
ß= beta ratio (d/D)
SG= specific gravity at line conditions (air=1.00)
SH= specific heat ratio cp/cv (air=1.4)
R
n
=Reynolds number at max flow in pipe.
K= C x ((1)/( 1-ß
4
))
Y= 1- (.41+.35ß
4
) ((h/w x .0361)/ (P
L
x 1.4))
C= 0.5959 + 0.0312Я
2.1
– 0.1840Я
8
+ 91.71Я
2.5
R
n
-0.75
If Reynolds number (R
n
) is not known, “C” can be estimated as
0.6015. For convenience other factors can be combined to form
constants as the equation is developed.
WATER AND LIQUID FLOW - CONCENTRIC BORE
Where:
44.748= physical constant
d= bore in inches
D= Pipe Inside Diameter (inches)
K= flow coefficient
Y= expansion factor (Water and most liquids normally=1)
Fa= thermal expansion factor (Water and most liquids
normally=1)
h/w= differential pressure (inches w/c)
P
L
= density @ Line (flowing) conditions in lbs./ft
3
C= 0.5959+ 0.0312Я
2.1
– 0.1840Я
8
+ 91.71Я
2.5
R
n
-0.75
ß= Beta Ratio (d/D)
SCFM =
5.9816 x (d
2
) x (K) x (Y) x h/w x (2.703 x P
L
x SG)/(460 + T
L
)
√
√
2.703 x 14.7 x SG
460 + T
b
√
K = C x (1) / ( 1-ß
4
)
√
√
Q (GPM) = 44.748 x d
2
x K x Y x Fa x (hw)/(
P
L
)
F-OP bulletin:F-OP bulletin 7/24/09 10:06 AM Page 4