avco orifice plates

8/20/2019 AVCO Orifice Plates

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PADDLE TYPE ORIFICE PLATE

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

UNIVERSAL TYPE ORIFICE PLATE

The Universal Type Orice Plate is designed to be used in an orice tting. Line sizes 2”-10” require aremovable Orice Plate Seal. Depending on the service, these seals are made of Nitrile, TFE, orstainless steel. Line sizes 12” and above require the seal to be vulcanized to the O.D. of the plate. Thebore geometry of the Universal Type Orice Plate is the same as the Paddle Type Orice Plate. Caremust be taken installing Eccentric Bored Plates and Orice Plates with weep holes, to assure they arerotated in the correct position. Segmental Orice are not recommended in Universal Type Orice Plates.

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

FLOW MEASUREMENT

DEVICES



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

This is the standard ow element “FE” type orice plate. The orice isbeveled on the downstream edge, in accordance 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 orice bore divided by the line I.D. is calledthe beta ratio“β”. The “β ratio should be between .2 and .7. The ac-

curacy of the ow coefcient diminishes beyond these limits.

Instead of beveling the downstream face of the orice plate at 45°, aCounter Bore is another method of reducing the throat thickness tothe “e” dimension. The Counter Bore diameter is equal to the boreplus dimension “A”.

The outside diameter of the bevel of the Eccentric Orice is tangent to8% of the line I.D. When set at the top of the line, entrained gases

n a liquid will pass the orice.

he Quadrant Orice is designed to measure the ow of high viscosityuids, and is recommended when the Reynolds Number is below

10,000. Quadrant Orices maintain a constant coefcient in laminarow. The radius “R” is a function of the β ratio. The thickness of therice is equal to quadrant radius “R”. The thickness of the orice

plate is equal to “R” rounded up to the next 1/8” increment. Forxample if R=.899, the orice plate would be 1 inch thick. Due to the

hickness and rounded entrance edge, the plate is very durable.

The Segmental Orice bore is designed for uids con taining heavysediments. The diameter ”D” is equal to 98% of the line I.D. “H” is the

eight of the circular segment. The β ratio is equal to the equivalentcircular diameter of segment divided by the line I.D. The SegmentalOrice is the most difcult type of orice to manufacture, requiringnishing by hand.

The purpose of the Restriction Orice is to reduce the ow rate orto create a pressure drop. The Restriction Orice plates are placeddownstream of a turbine meter to guard against over-spin. A RestrictionOrice is denoted by “RO” or “FO”. When specifying a RestrictionOrice, plate thickness “E” should be thick enough to reduce platedeection to a minimum. As a rule, the maximum pressure drop acrossa single orice for a gas is 50%. For greater drops, multiple orices

ay be used. Cavitation and excessive noise can be a problem.





PERMANENT PRESSURE DROP VS. BETA RATIO FOR

PERMANENT PRESSURE DROP VS. BETA RATIO FOR

DIFFERENTIAL DEVICES

70

20

10

. . . . . . . .

P E

R M A N E N T P R E S S U R E L O S

%

P E R M A N E N T P R E S S U R E L O S

PERMA

BETA RATIO

avco orifice plates

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