其中P25頁的第6章Pressure Gauge Testing 有我們關心的內容
6.2.4.1(b) All Grade.Known pressure shall be applied at each test point on increasing(or vacuum). At each test point the gauge shall be read,lightly tapped, and then read again. The difference reading is friction error.
對于所有等級的壓力表。在升壓行程逐步施加已知壓力在每個測試點。讀取每個測試點上壓力表讀數，然后輕敲，再讀取一次。兩次讀數差值即為壓力表的摩擦誤差。
friction error 好像就是咱們國家的“輕敲位移”吧。
The same sequence shall be repeated on decreasing (or vacuum). The entire set of upscale and downscale reading shall then be repeated.
THe error can be determined from the data abtained in the two pressure cycles and is equal to maximum error at each test point, in either direction, after tapping.