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Shanghai Chaohui Pressure Instrument Co., Ltd
How to choose the diaphragm for high-temperature melt pressure transmitter?
Date: 2025-11-20Read: 1
In special environments such as molten metal, petrochemicals, or nuclear industries, ChaohuiHigh temperature melt pressure transmitterIt is the core component for measuring key parameters. Its weakest and most important component is the diaphragm - it directly withstands high pressure, high temperature, and strong corrosive media, and is the "first line of defense" of the entire sensing system. 
1. What isHigh temperature melt pressure transmitterWhy is the membrane so important?
Working principle: The diaphragm is located in front of the measuring chamber (or "gas chamber"), and when a medium (such as molten metal, petroleum liquid, or steam containing acid or alkali) is pressed on it, the diaphragm undergoes deformation. This deformation is converted into an electrical signal to achieve pressure measurement.
Challenge:
High temperature (>300 ° C, sometimes up to 800-1000 ° C).
High pressure (1030 MPa or higher).
Strong corrosive media (sulfur-containing, chloride, acid-base, etc.).
Mechanical fatigue: Prolonged cyclic loading leading to membrane cracking or failure.
Therefore, the material selection of the diaphragm determines whether the sensor can work stably for a long time.
2. Performance Comparison - Indicators You Need to Pay Attention to
indicator
174PH 155PH C276
Yield strength (25 ° C)
510–850 MPa 410–770 MPa 730–1000 MPa
tensile strength
690–930 MPa 580–830 MPa 1000–1250 MPa
elongation
20–40 % 25–35 % 15–30 %
Hardness (HRC)
28–34 24–32 32–38
Corrosion resistance (seawater/sulfide)
Medium to high
Maximum available temperature
~350 ° C~350 ° C 400-800 ° C (depending on post-processing)
main points:
Strength vs. Elongation: The membrane needs to be able to withstand high pressure without being brittle due to being too hard.
Corrosion resistance: C276 performs best in sulfur-containing or chloride containing melts.
Maximum temperature: If the operating temperature exceeds 400 ° C, 174PH/155PH will lose structural integrity.
3. Dimensions and Geometry:
The thickness of the membrane is generally 0.5-3mm; too thin is prone to breakage, while too thick reduces sensitivity.
The surface should be smooth and free of notches to avoid localized stress concentration.
4. Installation:
Ensure the matching between the sealing ring and the pressure plate; Poor contact can lead to air leakage and measurement errors.
Regularly inspect welds or bolt connections to prevent loosening under high temperatures.
5. Installation and maintenance: tight coordination, regular inspection, and prevention of corrosion.
As long as the above five key steps are strictly monitored during the selection stage, it can be achievedHigh temperature melt pressure transmitterThe membrane works stably in harsh environments for a long time, avoiding expensive downtime and maintenance costs.
Remember: the diaphragm is the weakest but most important component in the measurement system; The choice of materials directly determines whether the sensor can withstand wind and rain.