How are the flat diaphragm and convex diaphragm chosen for differential pressure level gauges?
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This post was last edited by jlj913 on 2022-1-14 at 11:30. May I ask that the types of remote transmission diaphragms for differential pressure level gauges are flat diaphragms and convex diaphragms. Question: 1. Is it only media that crystallize easily that use convex diaphragms? 2. What are the advantages of choosing a flat diaphragm or a convex diaphragm? 3. How should the length of the capillary be calculated?
This post was last edited by hxch150804 on January 14, 2022, at 13:02. The protruding-diaphragm type is mainly designed for situations where the outlet pipe of the equipment is too long, making it difficult to provide insulation and heat tracing; this can cause the material to solidify within the outlet pipe, leading to measurement errors or even damage to the equipment. Therefore, the diaphragm is placed directly against the inner wall of the equipment, thereby preventing any solidification from occurring. If you have measures in place for insulation and heat tracing, you may also opt to use a flat-flange diaphragm. The protruding-flange diaphragm requires minimal maintenance; however, if it gets damaged, production must be halted for replacement. One advantage of the diaphragm flat flange is that it allows for the installation of a valve; in case of problems, the valve can be closed to enable maintenance at any time.
The pressure-sensing element of the transmitter is a diaphragm. Since there are dead corners in the measurement pipeline at a certain distance from where the medium reaches the diaphragm, as long as the measurement medium does not deposit in those sections of the pipeline, it will not have an impact on pressure transmission; in such cases, a flat diaphragm can be used； If the measuring medium tends to crystallize and clog the pressure lead sections at the interface, thereby affecting pressure transmission, a convex membrane is used; that is, the membrane tip is extended further into the measuring connection, eliminating any dead zones for pressure measurement. The capillary is used to measure the distance from the diaphragm to the transmitter, and its selection requires careful consideration of the location of the measurement interface as well as the installation location of the transmitter.
There are three types of remote diaphragms: Flush, Extended, and In-line Saddle. The latter two are preferred for materials that tend to crystallize. The length of the capillary should be as short as possible depending on the installation location; generally, it is advisable not to exceed 10 meters.