usp32 616 BULK DENSITY AND TAPPED DENSITY 堆密度和振实密度 ——中英对照

616BULK DENSITY AND TAPPED DENSITY

松密度和紧密度

The bulk density of a solid is often very difficult to measure since the slightest disturbance of the bed may result in a new bulk density. Moreover, it is clear that the bulking properties of a powder are dependent on the “history” of the powder (e.g., how it was handled), and that it can be packed to have a range of bulk densities. Thus, it is essential in reporting bulk density to specify how the determination was made.

固体的松密度的测量很困难，测量时，轻微的震动就会导致松密度的不同。因此，可以知道粉末的松散性取决于粉末的来历。而且压紧之后，会有一个密度范围。因此，报告松密度时，必须说明结果是如何得到的。

Because the interparticulate interactions that influence the bulking properties of a powder are also the interactions that interfere with powder flow, a comparison of the bulk and tapped densities can give a measure of the relative importance of these interactions in a given powder. Such a comparison is often used as an index of the ability of the powder to flow. The bulk density often is the bulk density of the powder “as poured” or as passively filled into a measuring vessel. The tapped density is a limiting density attained after “tapping down,” usually in a device that lifts and drops a volumetric measuring cylinder containing the powder a fixed distance.

微粒的相互作用不仅影响粉末的松散性，而且影响粉末的流速。粉末的松密度和紧密度的比较，可以看出微粒的相互作用的相对重要性的量度标准。这样一个比较常被用于粉末流动能力的一个指标。粉末的松密度的测量就是直接将粉末倾入一个量器。紧密度是被叩后的极限密度，通常使用一个设备，将一个装有固定高度粉末的量筒举起，落下。

BULK DENSITY

Bulk density is determined by measuring the volume of a known mass of powder sample that has been passed through a screen into a graduated cylinder (Method I) or through a volume-measuring apparatus into a cup (Method II).

松密度的测量是将已知质量的样品的粉末过筛进入一个量筒（方法Ⅰ）或通过一个体积测量器进入一个容器（方法Ⅱ）。

Method I—Measurement in a Graduated Cylinder

方法Ⅰ:用量筒测量

Procedure— Unless otherwise specified, pass a quantity of material sufficient to complete the test through a 1.00-mm (No. 18) screen to break up agglomerates that may have formed during storage. Into a dry 250-mL cylinder introduce, without compacting, approximately 100 g of test sample, M, weighed with 0.1% accuracy. If it is not possible to use 100 g, the amount of the test sample and the volume of the cylinder may be modified and the test conditions specified with the results. Select a sample mass having an untapped apparent volume of 150 to 250 mL. A 100-mL cylinder is used for apparent volumes between 50 mL and 100 mL. Carefully level the powder without compacting, if necessary, and read the unsettled apparent volume, V o, to the nearest graduated unit. Calculate the bulk density, in g per mL1, by the formula:

步骤：除非有特殊说明，先将足够量的样品过筛（1.00-mm 编号18）去除存储时可能形成的大块。称取约100g（精确至0.1%）的样品置250-mL的量筒，不要压实。如果不可能用100g样品，样品量和量筒大小可以改变。报告结果时说明测试条件。样品的质量的选择为不叩实外观体积为150至250mL.一个100-mL的量筒可用于的外观体积为50mL 和100mL之间。小心地夷平样品粉末不要压实，如果需要，读取未处理的外观上的体积，V0至最接近的刻度。计算松密度，g/mL ,用下列公式：

(M) / (V o).

Generally replicate determinations are desirable for the determination of this property.

一般需重复测量。

Method II—Measurement in a Volumeter

方法Ⅱ：用体积计测量

The apparatus (Fig. 1),