portant; word-wrap: break-word !important; font-size: 16px;">portant; word-wrap: break-word !important;">量器的容量随着温度而改变。量器在量入或量出其标称容量时的温度为标准温度。制造量器的玻璃，其体热膨胀系数约在10X 10portant; word-wrap: break-word !important; font-size: 16px; font-family: 宋体; vertical-align: super;">-6portant; word-wrap: break-word !important;">~30X 10portant; word-wrap: break-word !important; font-size: 16px; font-family: 宋体; vertical-align: super;">-5portant; word-wrap: break-word !important;">Kportant; word-wrap: break-word !important; font-size: 16px; font-family: 宋体; vertical-align: super;">-portant; word-wrap: break-word !important; font-size: 16px; font-family: 宋体; vertical-align: super;">1portant; word-wrap: break-word !important;">的范围内。一个体热膨胀系效为30X 10portant; word-wrap: break-word !important; font-size: 16px; font-family: 宋体; vertical-align: super;">-6portant; word-wrap: break-word !important;">Kportant; word-wrap: break-word !important; font-size: 16px; font-family: 宋体; vertical-align: super;">-portant; word-wrap: break-word !important; font-size: 16px; font-family: 宋体; vertical-align: super;">1portant; word-wrap: break-word !important; font-size: 14px; font-family: 宋体;">portant; word-wrap: break-word !important;">的(portant; word-wrap: break-word !important;">用钠钙玻璃制造的portant; word-wrap: break-word !important; font-size: 16px; font-family: Calibri;">)portant; word-wrap: break-word !important;">量器在portant; word-wrap: break-word !important; font-size: 16px; font-family: Calibri;">20portant; word-wrap: break-word !important;">℃下校准，portant; word-wrap: break-word !important;">而在27℃下使用时只显示portant; word-wrap: break-word !important; font-size: 16px; font-family: Calibri;">0.02% portant; word-wrap: break-word !important;">的附加误差，它小于大多数量器的极限误差，由此可见，标准温度在实际使用中是不重要的，但是为了提供良好的校准基准，规定一个标准温度并在校准前使量器在该温度下达到均衡是很重要的。
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portant; word-wrap: break-word !important; font-size: 16px;">portant; word-wrap: break-word !important; font-family: 宋体; font-weight: bold;">2）portant; word-wrap: break-word !important; font-family: 宋体;">液体的温度
portant; word-wrap: break-word !important; font-size: 14px; font-family: 宋体;">portant; word-wrap: break-word !important;">测量校准量器用水的温度的准确度应为±portant; word-wrap: break-word !important; font-size: 16px; font-family: Calibri;">0.1portant; word-wrap: break-word !important;">℃，在使用量器时，应保证其所有液体在测量其容积时都应在同一室温下。
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portant; word-wrap: break-word !important; font-size: 16px;">portant; word-wrap: break-word !important; font-size: 14px; font-family: 宋体; font-weight: bold;">3）portant; word-wrap: break-word !important;">玻璃表面的清洁度
portant; word-wrap: break-word !important; font-size: 16px; font-family: 宋体;">量器在量入或量出液体的容量时与其内表面的清洁度有关，清洁度差会使弯液面畸形而引起误差，这种弯液面的缺陷有两种。玻璃表面不完全湿润，即液体表面与玻璃以明显的角度接触，而不是形成曲线与玻璃表面相切。由于液体表面污染而减少了表面张力，使曲率半径增加。用于量出液体的量器，内壁不清洁则可使内壁上的液膜分布不规则或不完整而引起误差。若有化学沽污，即使不影响容量，也可能因化学反应使浓度变化而产生误差。配有磨口塞的容器应特别注意清洗研磨区。
portant; word-wrap: break-word !important; font-size: 14px; font-family: 宋体;">portant; word-wrap: break-word !important;">要确定量器是否彻底清洗干净，应在充液时进行观察(portant; word-wrap: break-word !important;">量出式的量器最好从液面以下充液，即从滴定管的旋塞阀下部，或从吸量管的流液口portant; word-wrap: break-word !important; font-size: 16px; font-family: Calibri;">)portant; word-wrap: break-word !important;">，弯液面升高而不变形portant; word-wrap: break-word !important; font-size: 16px; font-family: Calibri;">(portant; word-wrap: break-word !important;">即在其边缘处不起皱portant; word-wrap: break-word !important; font-size: 16px; font-family: Calibri;">)portant; word-wrap: break-word !important;">。在充液超过标称容量后，应将多余液体放出portant; word-wrap: break-word !important; font-size: 16px; font-family: Calibri;">(portant; word-wrap: break-word !important;">量出式量器应通过流液口排液，量入式量器应使用吸管吸出portant; word-wrap: break-word !important; font-size: 16px; font-family: Calibri;">)portant; word-wrap: break-word !important;">。上部的玻璃表面应保持湿润均匀，在边缘处弯液面不应起皱变形。
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portant; word-wrap: break-word !important; font-size: 16px;">portant; word-wrap: break-word !important; font-size: 14px; font-family: 宋体; font-weight: bold;">4）portant; word-wrap: break-word !important;">弯液面的调定
portant; word-wrap: break-word !important; font-size: 16px; font-family: 宋体;">弯液面是指待测容量的液体与空气之间的界面。
portant; word-wrap: break-word !important; font-size: 14px; font-family: 宋体;">portant; word-wrap: break-word !important;">大多数量器都可采用对照基准线或分度线来调定和读取弯液面。弯液面应该这样调定:
portant; word-wrap: break-word !important; font-size: 16px;">portant; word-wrap: break-word !important;">弯液面的最低点应与分度线上边缘的水平面相切，视线应与分度线上边缘在同一水平面上。然而水银弯液面应按其最高点与分度线下边缘水平相切当使用不透明液体，视线的水平线应通过弯液面的上边缘，必要时应做适当的校准portant; word-wrap: break-word !important; font-size: 14px; font-family: 宋体;">(portant; word-wrap: break-word !important;">见图portant; word-wrap: break-word !important; font-size: 16px; font-family: Calibri;">)
portant; word-wrap: break-word !important; font-size: 16px;">portant; word-wrap: break-word !important; font-size: 14px; font-family: 宋体;">
portant; word-wrap: break-word !important; font-family: 宋体; font-size: 16px;">适当安排光线可以使得弯液面暗淡且轮廓清晰，为此，应衬以白色背景，并遮去不需要的杂光。例如，可以在量器定位液面以下不大于1mm处，放置一条黑色纸带或用一小段切开的黑色厚胶管箍在量器管壁上。
portant; word-wrap: break-word !important; font-family: 宋体; font-size: 16px;">当分度线的长度足以同时从量器前后观察时，视线应处于上边缘前后部分重合的位置上，可以避免视差。量器只在前面具有分度线时，使用黑色遮光带来调定分度线上边缘，视差可以忽略不计，但也应注意，眼睛应与分度线上边缘在同一水平面内读数。
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portant; word-wrap: break-word !important; font-size: 16px;">portant; word-wrap: break-word !important; font-family: 宋体; font-weight: bold;">5）portant; word-wrap: break-word !important; font-family: 宋体;">流出时间
portant; word-wrap: break-word !important; font-family: 宋体; font-size: 16px;">对于量出式量器，由于量器内壁上遗留的液膜而使量出的容量总是小于量入的容量。液膜的容量与液体流出的时间有关。当流出时间超过一定值后，剩余液膜的容量就极小而且不变，因此，量出液体容量误差的影响可忽略不计。
portant; word-wrap: break-word !important; font-family: 宋体; font-size: 16px;">流出时间被分成若干段并有一定的等待时间也可以达到同样的效果，当流液口破损或堵塞，以及任何为了增快流速而改变流液口尺寸的做法都会引起读数误差。这种误差降低了读数的准确性，而且不能估算。
portant; word-wrap: break-word !important; font-family: 宋体; font-size: 16px;">流出时间适用于量出式以水作为液体的玻璃量器。实际流出时间在该范围内变化将不会有不合理的容量差异，但为安全起见，应规定出流出时间范围。流出时间仍可标在A 级滴定管和吸量管上，使用者可以通过测量流出时间来检查流液口是否堵塞或损坏。
小结
portant; word-wrap: break-word !important; font-size: 16px;">实验室玻璃量器准确度的这些影响因素，真的不是小题大做，在某些时候，这些影响因素会成为总不确定度的主要贡献，一定要引起重视。
