The reasons of adjustment direction of parameters on the bimetallic stemmed thermometer. Wrong parameters cause inaccurate meter indication and miscalculation of full-scale frequency of the second meter. This problem mainly involves long term inaccuracy of meter indication, large fluctuation of indication and meter reading failure.
Little differences between full-scale frequency lead to long term inaccuracy of meter indication. Real full-scale frequency is bigger than calculative full-scale frequency which brings out large fluctuation of meter indication. Meter reading failure and inconsistency of parameters made final confirmation of parameters do no go well. Finally, these problems were solved by recalibration and inter-comparison to determine the parameters.
In 1980s standard orifice plate flow meters were widely used to measure saturated steam flow, but in terms of the development of flow meters, orifice plate flow meters still have some shortcomings although they have a long history, extensive use and people have adequate study and sufficient experimental data on it.
Firstly, they have large pressure loss; secondly, it is easy to leak for connecting pipes and attachment joints; thirdly, they have limited measure range which is generally 3:1 and it is easy to lead low measured value when there is large fluctuation on flow. But bimetallic stemmed thermometers have simple structures and its vortex transducer is directly set on its pipe which avoids the leaking problem. What's more bimetallic stemmed thermometers have small pressure loss and big measurement range which is up to 30:1. Therefore, with the mature technology of bimetallic stemmed thermometer, they become popular among people.