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What is DN?
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DN stands for 'Diameter Nominale'.
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½"
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DN15
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6"
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DN150
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¾"
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DN20
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8"
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DN200
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Put simply, it is a rough translation of mm from imperial sizes, assuming that an inch is 25mm.
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1"
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DN25
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10"
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DN250
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1¼"
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DN32
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12"
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DN300
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We refer to a 12" flange as DN300, when in fact it is 304mm.
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1½"
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DN40
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14"
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DN350
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2"
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DN50
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15"
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DN375
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2½"
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DN65
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16"
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DN400
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3"
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DN80
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18"
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DN450
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4"
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DN100
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20"
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DN500
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5"
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DN125
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24"
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DN600
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What is the PCD?
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The PCD of a flange is one of the critical dimensions.
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PCD (Pitch Circle Diameter) is the diameter of a circle that goes through each of the bolt holes.
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British Standard - BS10
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Table D
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Table E is the most popular for applications with water.
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Table E
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All dimensions are specified in inches.
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Table F
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Table G
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Table H
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Table J
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Table K
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American National Standards Institute (ANSI)
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ANSI 125
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Higher numbers denote higher pressures.
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ANSI 150
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Sometimes people use the word 'Class' instead of ANSI. e.g. an ANSI 150 flange might be called a 'Class 150'
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ANSI 300
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All dimensions are specified in inches.
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ANSI 600
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ANSI 900
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ANSI 1500
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British Standard - BS4504
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BS4504-6
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PN6
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Engineers use the prefix PN (Pressure Nominale). e.g. a BA4504-16 flange will commonly be referred to as a PN16
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BS4504-10
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PN10
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Generally, a PN16 flange is designed to withstand pressures up to 16 bar.
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BS4504-16
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PN16
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All dimensions are specified in mm.
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BS4504-25
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PN25
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BS4504-40
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PN40
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BS4504-64
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PN64
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BS4504-100
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PN100
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SABS 1123
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SABS 1123-600
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SABS 1123-1000
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SABS 1123-1600
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SABS 1123-2500
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SABS 1123-4000
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