Orifice plate differential range
Orifice plate differential range
(OP)
Hi
One of the orifice plate specification has following clause:
For Compressible fluids differential range in inches of water shall not exceed the normal upstream static pressure in psi absolute except that for exhaust steam.
My question is - why this is applicable only for compressible fluids and what is the significance of this statement?
Thank you.
One of the orifice plate specification has following clause:
For Compressible fluids differential range in inches of water shall not exceed the normal upstream static pressure in psi absolute except that for exhaust steam.
My question is - why this is applicable only for compressible fluids and what is the significance of this statement?
Thank you.





RE: Orifice plate differential range
Keith Cress
kcress - http://www.flaminsystems.com
RE: Orifice plate differential range
RE: Orifice plate differential range
Best to you,
Goober Dave
Haven't see the forum policies? Do so now: Forum Policies
RE: Orifice plate differential range
David Simpson, PE
MuleShoe Engineering
Law is the common force organized to act as an obstacle of injustice Frédéric Bastiat
RE: Orifice plate differential range
a routine requirement for plate type meters from early days to the present
imposed to minimize errors associated with the expansion factor correction
RE: Orifice plate differential range
RE: Orifice plate differential range
Most orifice run dP transmitters I've seen fall into 1 of 3 ranges - 0-50, 0-100, and 0-200" w.c. Rarely have I seen them exceed 200" w.c. because more than that and you get into deflection of standard orifice plates in larger pipe runs. So, above 200 psia, I don't think I'd follow this simple rule.
Good luck,
Latexman
Technically, the glass is always full - 1/2 air and 1/2 water.
RE: Orifice plate differential range
R.W. Miller indicates the following formula for orifice plate thickness
tmin ≥ SQRT [(0.681-0.651*BETA)*deltaP/Y] * pipe ID
where:
tmin = min plate thickness [mm]
BETA = ratio of orifice hole diameter to pipe diameter
deltaP = pressure drop [MPa]
Y = plate material yield stress [MPa]
Pipe ID = pipe internal diameter [mm]
Your specific material properties and geometric configuration could give us more details to think about.
Obviously if were on the right track, the limitation above shouldn't be restricted only to compressible fluids (gases) but should be extended to liquids as well.
RE: Orifice plate differential range
have not seen such round robin confusion over the expansion factor and whether it applies to compressible or incompressible flows, this forum is for added value not mucking things up
my two cents
RE: Orifice plate differential range
Keith Cress
kcress - http://www.flaminsystems.com
RE: Orifice plate differential range
consult any handbook that covers flow meter engineering from the 40's on.
The expansion factor is an empirical correction for compressible flow through an edged meter. Venturi's and flow nozzles use a theoretical correction rather than empirical.
good luck on your studies
RE: Orifice plate differential range
Keith Cress
kcress - http://www.flaminsystems.com