PADDLE TYPE ORIFICE PLATE

CAT No. A520 PADDLE ORIFICE PLATED = Inside Line I.D. d = Orifi ce Bore DiameterG = Vent & Drain Hole Diameter E = Orifi ce Plate ThicknessDw = Diameter of Vent & Drain Hole Circle e = Orifi ce Throat Thickness emax = The Smaller of D/50 or d/8

UNIVERSAL TYPE ORIFICE PLATE

The Universal Type Orifi ce Plate is designed to be used in an orifi ce fi tting. Line sizes 2”-10” require a removable Orifi ce Plate Seal. Depending on the service, these seals are made of Nitrile, TFE, or stainless steel. Line sizes 12” and above require the seal to be vulcanized to the O.D. of the plate. The bore geometry of the Universal Type Orifi ce Plate is the same as the Paddle Type Orifi ce Plate. Care must be taken installing Eccentric Bored Plates and Orifi ce Plates with weep holes, to assure they are rotated in the correct position. Segmental Orifi ce are not recommended in Universal Type Orifi ce Plates.

BB

AA

C

D Dw d

"G" VENT

"G" DRAIN

1/4" HOLE

STAMPED

45°

e

E

AVCOTAG No.

BORE SIZE

INLETSIZE RATING

MATERIALUSA

AVCO

AVCOMATERIALLINE SIZEOUTLETBORE

TAG NO.

STAMPED

45°

de

E

AA

Per I.S.A. RP 3.2

3087 S. Harbor Blvd, Santa Ana, CA 92704 Tel (714) 427-0877 Fax (714) 427-6392 Web-site: www.avcovalve.com

FLOW MEASUREMENTDEVICES

AVCO CONTROLS ORIFICE PLATESAVCO manufactures Orifi ce Plates from 1/4”-96” in line size. The standard material of construction is 316 stainless steel. Orifi ce Plates are manufactured in strict accordance to AGA, ISA, ASME, API, and ISO standards. Special custom designs are also available. AVCO has a complete engineering department to assist in product selection and application.

This is the standard fl ow element “FE” type orifi ce plate. The orifi ce is beveled on the downstream edge, in ac cor dance to AGA report #3. The purpose of the bevel is to reduce the width of the throat to the “e” dimension. The ratio of the or i fi ce bore divided by the line I.D. is called the beta ratio“β”. The “β” ratio should be between .2 and .7. The ac-curacy of the fl ow coeffi cient diminishes beyond these limits.

Instead of beveling the downstream face of the orifi ce plate at 45°, a Counter Bore is another method of reducing the throat thickness to the “e” dimension. The Counter Bore di am e ter is equal to the bore plus dimension “A”.

The outside diameter of the bevel of the Ec cen tric Orifi ce is tangent to 98% of the line I.D. When set at the top of the line, entrained gases in a liquid will pass the orifi ce.

The Quadrant Orifi ce is designed to measure the fl ow of high vis cos i ty fl uids, and is rec om mend ed when the Reynolds Number is be low 10,000. Quad rant Orifi ces main tain a con stant coeffi cient in lam i nar fl ow. The ra di us “R” is a function of the β ratio. The thick ness of the orifi ce is equal to quad rant radius “R”. The thickness of the orifi ce plate is equal to “R” rounded up to the next 1/8” in cre ment. For ex am ple if R=.899, the orifi ce plate would be 1 inch thick. Due to the thickness and round ed entrance edge, the plate is very du ra ble.

The Segmental Orifi ce bore is designed for fl uids con tain ing heavy sed i ments. The di am e ter ”D” is equal to 98% of the line I.D. “H” is the height of the circular segment. The β ra tio is equal to the equiv a lent circular diameter of seg ment divided by the line I.D. The Seg men tal Orifi ce is the most diffi cult type of or i fi ce to manufacture, requiring fi n ish ing by hand.

The purpose of the Restriction Orifi ce is to reduce the fl ow rate or to create a pressure drop. The Restriction Orifi ce plates are placed downstream of a turbine meter to guard against over-spin. A Re stric tion Orifi ce is denoted by “RO” or “FO”. When specifying a Re stric tion Orifi ce, plate thick ness “E” should be thick enough to re duce plate de fl ec tion to a minimum. As a rule, the max i mum pres sure drop across a single orifi ce for a gas is 50%. For greater drops, multiple orifi ces may be used. Cavitation and excessive noise can be a problem.

STANDARD CONCENTRIC ORIFICE

ECCENTRIC ORIFICE

BEVELDIA.LINE I.D.

SEGMENTAL ORIFICE

LINE I.D.

RESTRICTION TYPE ORIFICE

NO BEVEL

QUADRANT BORED ORIFICE

QUADRANTRADIUS

COUNTER BORED ORIFICE

3087 S. Harbor Blvd, Santa Ana, CA 92704 Tel (714) 427-0877 Fax (714) 427-6392 Web-site: www.avcovalve.com

3087 S. Harbor Blvd, Santa Ana, CA 92704 Tel (714) 427-0877 Fax (714) 427-6392 Web-site: www.avcovalve.com

PERMANENT PRESSURE DROP VS. BETA RATIO FOR OR I FICE PLATES WITH FLANGE TAPS

PERMANENT PRESSURE DROP VS. BETA RATIO FOR DIFFERENTIAL DEVICES

10010090908080707060605050

4040

3030

2020

10109988776655

44

33

22

100 .1.1 .2.2 .3.3 .4.4 .5.5 0.60.6 .7.7 .75.75 88

SQUARE EDGE ORIFICE PLATE

FLOW NOZZLE

VENTURI 15° EXIT CONE

HERSCHEL VENTURI7° EXIT CONE

UNIVERSAL VENTURI TUBE

LOW LOSS VENTURI

100

90

80

70

60

50

400 .10 .20 .30 .40 .50 .60 .70 .80

PERMANENT PRESSURE DROP VS BETA RATIOFOR ORIFICE PLATE WITH FLANGE TAPS

PER

MAN

ENT

PRES

SUR

E LO

SS%

OF

DIF

FER

ENTI

AL P

RES

SUR

E

BETA RATIO = ORIFICE BORELINE I.D.

PER

MAN

ENT

PRES

SUR

E LO

SS%

OF

DIF

FER

ENTI

AL P

RES

SUR

E

PERMANENT PRESSURE LOSSPERMANENT PRESSURE LOSS PPLPPLP 1-0.24 -0.52 -0.16 P

BETA RATIO