本文件规定了一种测量金属粉末填充层的透气性和孔隙率的方法，以及由此得出外壳比表面积值的方法。渗透性是在稳态流动条件下，使用压力接近大气压的层流空气确定的。本文件不包括用定容法测量渗透率。 已经提出了几种不同的方法用于该测定，并且有几种试验装置可在市场上买到。如果遵守本文件中给出的一般说明，且试验参数相同，则它们给出了类似的、可重复的结果。 本文件未规定特定的商业试验装置和相应的试验程序。 然而，为了方便用户，已包含一份资料性附录（见附录A），旨在提供关于三种具体方法的一些实用信息: -Lea和护士方法，包括可在实验室内制造的测试设备（见a.1）； -张瑞福法，使用类似的试验装置（见a.2）； -Gooden和Smith方法，涉及一个可以在实验室中建造的测试设备，但也存在一个商业测试设备。（现有两种商用测试设备；其中一种不再可供购买，但仍在使用，见A.3。） 这些方法仅作为示例给出。在本文件范围内，可接受各国提供的其他测试设备。 本试验方法适用于所有金属粉末，包括直径不超过1000μm的硬质合金粉末，但通常用于直径介于0.2μm和75.0μm之间的颗粒。 除非有关各方明确约定，否则其不适用于由形状远离等轴的颗粒组成的粉末，即薄片或纤维。 本试验方法不适用于不同金属粉末或含有粘合剂或润滑剂的粉末的混合物。 如果粉末中含有附聚物，测量的表面积可能会受到附聚程度的影响。如果粉末经过去团聚处理（见附录B），则所用方法应由有关各方商定。

This document specifies a method of measuring the air permeability and the porosity of a packed bed of metal powder, and of deriving therefrom the value of the envelope-specific surface area. The permeability is determined under steady-state flow conditions, using a laminar flow of air at a pressure near atmospheric. This document does not include the measurement of permeability by a constant volume method. Several different methods have been proposed for this determination, and several test devices are available commercially. They give similar, reproducible results, provided that the general instructions given in this document are respected, and the test parameters are identical. This document does not specify a particular commercial test device and corresponding test procedure. However, for the convenience of the user, an informative annex has been included (see Annex A) which is intended to give some practical information on three specific methods: — the Lea and Nurse method, involving a test device which can be built in a laboratory (see A.1); — the Zhang Ruifu method, using a similar test device (see A.2); — the Gooden and Smith method, involving a test device which can be built in a laboratory but for which a commercial test device also exists. (Two types of commercial test device exist; one of these is no longer available for purchase, but is still being used, see A.3.) These methods are given as examples only. Other test devices available in various countries are acceptable within the scope of this document. This testing method is applicable to all metallic powders, including powders for hardmetals, up to 1 000 μm in diameter, but it is generally used for particles having diameters between 0,2 μm and 75,0 μm. It is not intended to be used for powders composed of particles whose shape is far from equiaxial, i.e. flakes or fibres, unless specifically agreed upon between the parties concerned. This testing method is not applicable to mixtures of different metallic powders or powders containing binders or lubricant. If the powder contains agglomerates, the measured surface area can be affected by the degree of agglomeration. If the powder is subjected to a de-agglomeration treatment (see Annex B), the method used is to be agreed upon between the parties concerned.