Editing Pyrometric cone (section)

== Control of variability ==
Pyrometric cones are sensitive measuring devices and it is important to users that they should remain consistent in the way that they react to heating. Cone manufacturers follow procedures to control variability (within batches and between batches) to ensure that cones of a given grade remain consistent in their properties over long periods. A number of national standards<ref>{{cite web|title=Japan Pyrometric reference cones|url=http://www.webstore.jsa.or.jp/webstore/Com/FlowControl.jsp?bunsyoId=JIS+R+8101%3A1999&dantaiCd=JIS&status=1&pageNo=0&lang=en}}</ref><ref>{{cite web|title=China's Refractories|url=http://www.china-refract.org/cr/standard-pg1.htm}}</ref><ref>{{cite web|title=ASTM C24 Standard Test Method for Pyrometric Cone Equivalency(PCE) of Fireclay and High Alumina Refractory Materials|url=http://www.astm.org/Standards/C24.htm}}</ref> and an [[International Organization for Standardization|ISO]] standard{{hsp}}<ref>{{cite web|title=ISO 1146:1988-02|url=http://www.iso.org/iso/catalogue_detail.htm?csnumber=5688}}</ref> have been published regarding pyrometric cones.

Even though cones from different manufacturers can have relatively similar numbering systems, they are not identical in their characteristics. If a change is made from one manufacturer to another, then allowances for the differences can sometimes be necessary.