In-depth Analysis of the Technical Shortcomings of the ST-ST950 Pressure Transmitter Diffused Silicon Sensor

As a core component in industrial flow control, the diffused silicon sensor used in the ST-ST950 pressure transmitter has common shortcomings in practical applications, such as temperature drift and long-term stability issues. This article provides an in-depth analysis of the technical shortcomings of the ST-ST950 and similar series products, helping technical evaluators avoid procurement risks, providing key parameter comparisons for corporate decision-makers, and assisting financial approvers in making the most cost-effective choice.

I. Temperature Drift Issue: The Fatal Weakness of Diffused Silicon Sensors

The most prominent issue of diffused silicon pressure sensors in models such as the ST-ST950 is temperature drift. When the ambient temperature changes by more than ±10℃, the zero-point drift can reach 0.5% of span/55℃, which is particularly evident under high-temperature working conditions such as in electric power and metallurgy. In comparison, domestic capacitive pressure transmitter PQ70 high-accuracy intelligent differential pressure transmitter adopts digital temperature compensation technology to control temperature effects within ±0.25%/55℃, and its fully welded 316 stainless steel diaphragm structure is better suited to extreme environments of -40～100℃.

• Typical manifestation:Every 10℃ temperature change causes a 0.1%FS zero-point offset
• Industry comparison:The temperature stability of capacitive sensors is generally 3-5 times better than that of diffused silicon technology
• Solution:Choose models with automatic temperature compensation or switch to capacitive sensor technology

II. Long-term Stability Defect: Error Reaches 0.15% in Six Months

Our tracking tests on mainstream models in the market show that diffused silicon sensors, including LED-900 and HR-M2, exhibit an average accuracy degradation of 0.15% of span after 6 months of use. This is mainly due to the creep characteristics of silicon materials and the release of packaging stress. In contrast, the PQ70 transmitter featuring a fully solid-state design uses digital capacitive circuitry and sensor memory technology to control the six-month stability error within ±0.1%, making it particularly suitable for the long-cycle operation requirements of the petrochemical industry.

III. Medium Compatibility Limitations: Survival Challenges in Corrosive Environments

Diffused silicon sensors in models such as CY-CY3018 and HT-805 generally adopt a silicone oil-filled structure. When measuring corrosive media such as chlorine gas and ammonia gas, the diaphragm is prone to intergranular corrosion. The PQ70 series, however, provides multiple diaphragm options such as Hastelloy C and Monel, combined with fluororubber seals, enabling it to perfectly handle acid and alkali media. Measured data from a metallurgical enterprise show that under the same working conditions, the service life of the PQ70 is 2.3 times longer than that of traditional diffused silicon sensors.

IV. Cost-performance Analysis: The Art of Balancing Initial Cost and TCO

Although the purchase unit price of diffused silicon models such as BP-BP200 and SP-802 is lower (about 15-20% cheaper), considering factors such as replacement frequency and maintenance costs, the 3-year total cost of ownership (TCO) is instead 30% higher. This is especially true for high-precision scenarios such as instrument processing, where the labor cost brought by frequent calibration cannot be ignored. With its 40:1 turndown ratio and ±0.05% accuracy, the PQ70 can replace multiple traditional transmitters with a single unit, effectively reducing system integration costs.

Technical Decision-making Recommendations and Alternative Solutions

For different application scenarios, we provide the following professional recommendations:

1. High-temperature working conditions:Give priority to capacitive sensors with automatic temperature compensation, such as the PQ70 series
2. Corrosive environments:Choose a combined solution of Hastelloy diaphragm + fluororubber seal
3. Long-term stability requirements:Consider products with digital compensation technology and fully welded structure
4. Projects with limited budget:Economical diffused silicon models such as DG-DG1210 can be selected, but an additional 20% maintenance budget is required

As a national high-tech enterprise, Xi'an Shenghongchuang Instrumentation Co., Ltd.'s PQ70 series has passed IEC801 electromagnetic compatibility certification and has more than 200 successful cases in fields such as electric power and petrochemicals. This product adopts direct digital capacitive circuitry and remote range adjustment technology, perfectly solving the inherent defects of traditional diffused silicon sensors.

Contact our technical team now to obtain customized pressure measurement solutions, or learn more about the technical parameters and industry application cases of the PQ70 intelligent differential pressure transmitter.