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# Conversion of valve nominal diameter and inch | comparison table

Valve nominal diameter|valve nominal diameter
Definition of valve nominal diameter:

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Nominal diameter (or nominal diameter), also known as average outer diameter, refers to the size of all piping accessories in the piping system. The nominal diameter is a convenient round integer for reference. The nominal diameter of the valve is marked with a number followed by the letter DN. DN represents the internal diameter of the pipe in millimeters. For example, DN50 is 50 millimeters. The American standard valve is usually expressed in inches (“), and the fractional valve is to express the internal diameter of the pipe in inches. The conversion formula is 1”=25.4mm, such as 8” is equivalent to the domestic DN200mm.

Valve nominal diameter comparison table:
The nominal diameter of the valve (NPS-NOMINAL PIPE SIZE) is not necessarily the same as the diameter of the flow channel. For the selection of its size, the required Cv value is calculated from the conditions of the conveying fluid, and then the Cv value (refer to the manufacturer’s catalog) is used to select a suitable valve The nominal diameter (NPS) is the nominal inner diameter that characterizes the valve diameter. The national standard is expressed by DN and the unit is mm. The American standard is expressed in inches. The conversion relationship between inch NPS and metric DN is as follows:

 No. inch DN/mm No. inch DN/mm No. inch DN/mm 1 1/8 4 17 10 250 33 42 1050 2 1/4 8 18 12 300 34 48 1200 3 3/8 10 19 14 350 35 54 1350 4 1/2 15 20 16 400 36 60 1500 5 3/4 20 21 18 450 37 64 1600 6 1 25 22 20 500 38 72 1800 7 11/4 32 23 22 550 39 80 2000 8 11/2 40 24 24 600 40 84 2100 9 2 50 25 26 650 41 88 2200 10 21/2 65 26 28 700 42 96 2400 11 3 80 27 30 750 12 31/2 90 28 32 800 13 4 100 29 34 850 14 5 125 30 36 900 15 6 150 31 38 950 16 8 200 32 40 1000

TH Valve is a professional manufacturer of butterfly valvegate valvecheck valveglobe valveknife gate valve, ball valve with API, JIS, DIN standard, used in Oil, Gas, Marine industry, Water supply and drainage, fire fighting, shipbuilding, water treatment and other systems, with Nominal Diameter of DN50 to DN1200, NBR/EPDM/VITON, Certificates & Approvals: DNV-GL, Lloyds, DNV, BV, API, ABS, CCS. Standards: EN 593, API609, API6D