As an example Hozelock will list their micro irrigation pipe as having a diameter of 12mm. If the numbers read “90 – 3”, it is telling you that the fitting is a 90mm and it is a three-inch; but we know that it cannot be both, because they are different measurements. Both Hozelock and Gardena measure the diameter of their water pipe as an internal diameter. This image may not be used by other entities without the express written consent of wikiHow, Inc.
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\u00a9 2020 wikiHow, Inc. All rights reserved. The current practice is to determine pipe size through two numbers: 1) the pipe bore (or diameter) and 2) the pipe schedule (or wall thickness) – though these two numbers can be configured in slightly different ways depending on the specific pipe used. The metric system labels pipe diameters in millimetres, while the inch/imperial system labels pipe diameters in inches. This image is not<\/b> licensed under the Creative Commons license applied to text content and some other images posted to the wikiHow website. {"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/3\/3a\/Measure-Pipe-Size-Step-1.jpg\/v4-460px-Measure-Pipe-Size-Step-1.jpg","bigUrl":"\/images\/thumb\/3\/3a\/Measure-Pipe-Size-Step-1.jpg\/aid11182578-v4-728px-Measure-Pipe-Size-Step-1.jpg","smallWidth":460,"smallHeight":345,"bigWidth":"728","bigHeight":"546","licensing":"

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