Double Flange Level Transmitter Usage Guidelines and Comprehensive Guide

Overview of Double Flange Level Transmitters

The double flange level transmitter is a highly reliable instrument based on the differential pressure principle, designed for complex industrial conditions. Nexisense products use high-quality international components, explosion-proof structure suitable for all-weather use, and output DC 4-20mA with HART protocol. Range adjustments and variable monitoring are stored in EPROM to ensure long-term stability.

In industrial automation, these transmitters are the first choice for monitoring liquid levels in closed tanks. Field feedback shows that standardized use significantly reduces failure rates and improves process control efficiency.

Measurement Method

Double flange level transmitters measure liquid level via differential pressure. The high-pressure flange is installed at the tank bottom, and the low-pressure flange at the top or gas space. Isolated diaphragms sense the pressure, transmitted via filled capillary tubes (e.g., silicone oil) to the sensor body. Differential pressure is calculated as ΔP = ρgh, where ρ is the medium density, g is gravitational acceleration, and h is liquid height.

This remote-sealed design prevents the sensor from contacting the medium directly, suitable for high-temperature, high-pressure, corrosive, or viscous liquids. Nexisense transmitters include temperature compensation to minimize capillary length and ambient temperature effects, ensuring accuracy. Compared with single flange transmitters, it eliminates gas-phase pressure fluctuations, especially in pressurized vessels.

The measurement process includes post-installation venting, zero migration, and span calibration. HART protocol allows remote configuration, avoiding the need to open covers and improving safety.

Application Scenarios

Double flange level transmitters are widely used in chemical, petroleum, pharmaceutical, and food industries.   In chemical reactors, they monitor corrosive liquid levels to prevent overflow or empty tanks. In oil storage tanks, they handle high-temperature crude oil with capillaries rated up to 400°C. In pharmaceutical fermentation tanks, the isolated design ensures sterility and prevents contamination. In power boiler steam drums, they withstand high-pressure steam with explosion-proof safety.   Other applications include sewage treatment pressure tanks and LNG storage tanks. Nexisense capillary lengths can be customized 1-15m, suitable for large equipment, and combined with IoT for remote monitoring and enhanced intelligence.

Usage Precautions

Attention to detail ensures performance and longevity of double flange level transmitters:

• Tighten sealing nuts during wiring to prevent rain or moisture ingress that could cause short circuits or corrosion.

• For outdoor winter installations, use anti-freeze measures like heat tracing or insulation to prevent ice expansion damage to the diaphragm.

• Install capillary tubes in areas with minimal temperature fluctuation to reduce thermal expansion errors.

• Avoid locations with liquid impact or water hammer; overpressure may damage the sensor—consider adding a buffer device.

• When measuring liquid pressure, place taps on the side of the pipe to prevent sediment blockage on the diaphragm.

• Other considerations: capillary bend radius ≥50mm to prevent kinking; verify medium compatibility before installation; use shielded cables with single-end grounding to reduce interference.

Technical Parameters

Typical parameters for Nexisense double flange level transmitters: measurement range 0–10m liquid column (0–100kPa differential pressure), accuracy ±0.075%FS, stability ±0.1%/year. Output 4–20mA + HART, power supply 12–36VDC, power consumption<1W.   Capillary length 1–15m, fill fluid temperature range -40°C to 400°C, overload 200%FS. Protection IP67, explosion-proof Exd II CT6. Flange standards ANSI/DIN, materials 316L/Hastelloy/Tantalum. Response time <200ms, temperature effect <0.1%/10°C.   Selection should consider medium density, temperature, and installation height for proper matching.

Maintenance

Regular maintenance is key. Check cable seals and flange connections monthly; clean diaphragm surface with a soft cloth and neutral solvent; avoid high-pressure washing.   Quarterly calibrate zero and span using HART communicator to verify deviation<0.5%FS. Inspect capillaries for leaks or deformation; replace fill fluid if necessary.   Annual maintenance includes full inspection of circuit boards and seals, storing spares dry. Test anti-freeze measures before winter, ensure proper heat dissipation in summer. Nexisense provides remote diagnostics to support preventive maintenance and reduce downtime risks.   Common issue handling: temperature compensate when signal drifts; vent air bubbles if fluctuation occurs and recalibrate.

Installation and Commissioning

Ensure correct connection of high and low-pressure sides to avoid negative span. Commissioning includes filling and venting, zero adjustment, and density calibration. Integrate with DCS systems for alarm threshold setup to enhance safety.

FAQ

Which media are suitable for double flange level transmitters?
Corrosive, high-temperature, viscous, or volatile liquids. Not recommended for open vessels.

Does capillary length affect accuracy?
Longer capillaries increase delay, but Nexisense optimized design keeps impact within 0.1%.

How to prevent freezing in winter?
Add electric heat tracing or insulation to keep pressure taps above freezing.

What are the advantages of HART protocol?
Supports remote configuration, diagnostics, and multi-variable output for higher efficiency.

Conclusion

Paying attention to sealing, anti-freeze, temperature stability, and impact protection allows double flange level transmitters to achieve high precision and reliability. Nexisense products provide comprehensive support from measurement methods to maintenance, helping users handle complex conditions. Proper operation extends equipment life and ensures production safety. Selecting according to site conditions and regular maintenance promotes intelligent industrial measurement.