The article mainly introduces the error analysis, calculation of uncertainty in measuring the error of indication of needle DC voltmeter by DVM.
主要介绍采用“数表法”检定指针式电压表示值的误差分析及测量的不确定度的计算。
2
Needle valve: it is an important instrument measuring piping system components, mainly cut-off valve and ball valve, its purpose is to open or cut off access by pipeline.
针型阀：是仪表测量管路系统中重要组成部分，主要有截止阀和球阀，其功用是作开启或切断管道通路用。
3
A new device for measuring run out error of needle valve seat′s cone surface is proposed. The calculating and estimating methods of the error are also described in the paper.