A compression spring should be provided between the measuring element and the thermometer sleeve
Thread Content
The Specification for the Selection and Design of Automation Instruments in the Petrochemical Industry (SHT 3005-2016) states that \"a compression spring should be used between the measuring element and the thermometer sleeve.\" However, this issue is rarely taken into consideration in practical work. I would like to ask if anyone has structural diagrams related to this, and whether such requirements are mentioned when preparing plans
In some applications, springs are necessary. In the case of the temperature sensors used in the original polyethylene loop reactor, it was found that the thermistor elements were damaged after 5 months of operation; this was attributed to excessive vibration, and replacing them with ones equipped with springs resolved the issue. In my opinion, those with springs are suitable for measurement points subjected to excessive vibration.
The main goal is to reduce temperature lag; improved vibration resistance is a secondary benefit. To make a thermometer resistant to vibrations, it depends mainly on the strength of the protective tube – if there are springs in place, it’s less likely to get damaged, which indicates that the strength of the protective tube is insufficient
How to reduce temperature lag, and what is the principle behind it?
This is easy to understand: the spring ensures close contact between the temperature sensor and the protective sleeve