Copper alloy tube for pressure gauge
Copper alloy tubes for pressure gauges are precision tubing specifically designed for pressure measuring components in instruments such as pressure gauges and pressure sensors. Featuring excellent airtightness, corrosion resistance, and processability, they are indispensable for pressure measurement in industries such as industry, chemical engineering, and medicine. Common materials include brass (H62, H65), tin bronze (QSn6.5-0.1), and phosphor bronze (QSn4-3). H62 brass tubes offer high cost-effectiveness and are suitable for general industrial environments; QSn6.5-0.1 tin bronze tubes offer excellent corrosion resistance and elasticity, making them suitable for high-precision pressure gauges; and phosphor bronze tubes offer increased strength (tensile strength ≥500 MPa) and are used in high-pressure applications (≥10 MPa). Tubing typically has an outer diameter of 3-20 mm and a wall thickness of 0.5-2 mm. Extreme dimensional accuracy is required, with an outer diameter tolerance of ±0.02 mm and a wall thickness tolerance of ±0.01 mm to ensure accurate pressure measurement.
The production process for copper alloy tubes used in pressure gauges requires multiple precision machining steps to ensure dimensional accuracy and performance stability. First, high-quality copper alloy ingots or hot-rolled bars are selected as raw material and punched through a piercing machine to form a rough tube. The outer diameter of the rough tube is 5-10 mm larger than the finished product. Subsequently, the rough tube undergoes multiple cold rolling or cold drawing passes, gradually reducing the rough tube to the target size at a cold rolling speed of 5-10 m/min. Diamond dies are used during cold drawing to ensure a smooth surface finish (Ra ≤ 0.4 μm). Intermediate annealing temperatures range from 300°C to 500°C, depending on the material, to eliminate work hardening and restore the material’s plasticity. For high-pressure tubes, a hydraulic pressure test (pressure ≥ 1.5 times the working pressure) is required to ensure leak-free operation. After being cut and flattened, the finished tube undergoes airtightness testing (helium mass spectrometry leak detection, leak rate ≤ 1×10⁻⁹Pa・m³/s ) and mechanical property testing to ensure product quality.
In industrial pressure measurement, copper alloy tubes for pressure gauges are core pressure-measuring components. Common industrial pressure gauges utilize H62 brass tubes, bent into a C-shape or spiral. When pressure is applied, they elastically deform, driving the pointer to rotate. A pressure gauge from an instrument manufacturer achieves a measurement accuracy of ±0.5% FS. Pressure sensors for chemical pipelines utilize QSn6.5-0.1 tin bronze tubes, which are resistant to corrosion from acidic and alkaline media. This has extended the service life of a pressure measurement system at a chemical plant to five years. Pressure gauges in hydraulic equipment utilize phosphor bronze tubes, which can withstand high pressures up to 30 MPa. This has reduced the pressure control error of a hydraulic press to ±0.1 MPa.
The medical and food industries have stringent requirements for the safety and cleanliness of copper alloy tubes used in pressure gauges. Blood pressure gauges used in medical equipment utilize H65 brass tubes with electrolytically polished inner surfaces (Ra ≤ 0.2μm) to prevent bacterial growth. A medical equipment manufacturer’s blood pressure gauges have achieved ISO 13485 certification. Pressure measuring instruments in food processing equipment utilize lead-free brass tubes (lead content ≤ 0.01%), complying with FDA standards. The pressure measurement system in a beverage production line is free of metal ion migration contamination. Pressure gauges in pharmaceutical sterilization equipment utilize tin bronze tubes, capable of withstanding high-temperature steam sterilization at 121°C. This has improved the pressure control accuracy of a pharmaceutical company’s sterilization equipment by 10%.
With the advancement of industrial automation and precision measurement technology, the performance of copper alloy tubes used in pressure gauges continues to improve. Manufacturers have developed ultra-fine copper alloy tubes (outer diameter 1-3mm) for use in miniature pressure sensors, improving the blood pressure measurement accuracy of a smart wearable device to ±2mmHg. Heat-resistant copper alloy tubes (such as Cu-Cr-Zr alloy) have been developed for high-temperature and high-pressure environments. These tubes maintain stable performance at 200°C and 20MPa, making them suitable for aircraft engine pressure measurement. This has reduced the failure rate of engine pressure sensors at one airline by 40%. Laser processing technology has been used to achieve a dimensional accuracy of ±0.005mm, reducing pressure measurement error at a precision instrument manufacturer to ±0.1% FS. In the future, with the development of the Internet of Things and intelligent manufacturing, copper alloy tubes used in pressure gauges will become more miniaturized, more precise, and more intelligent. They will be integrated with sensors to form integrated pressure measurement units, improving the efficiency and reliability of pressure measurement.
