
Home » Products » Level Measuring Instruments » Bi Color Level Gauge for Boilers

The observation windows of the bi color level gauge are arranged in two straight lines along the length of the gauge body. By adopting a staggered combination of observation holes, the central blind area is effectively eliminated, ensuring continuous and clear level visibility.
Red and green light emitted by the built-in light-emitting diodes are separately directed toward the observation window. In the vapor phase section of the gauge body, the red light travels directly toward the viewing direction, while the green light is refracted toward the chamber wall and absorbed.
In the liquid phase section, due to the refraction effect of the liquid, the green light is directed straight toward the observation window, while the red light is deflected toward the wall and absorbed. As a result, when viewed from the front, the vapor phase appears red and the liquid phase appears green, providing a clear and intuitive bi-color level indication.
Level Measuring Instruments Description
Bi-Colour Level Gauges-Features
Direct visual indication of the actual liquid level, allowing real-time observation without electrical power or signal conversion.
Equipped with an automatic quick shut-off mechanism that isolates vapor and liquid flow in case of leakage or glass damage, enhancing operational safety.
Well-engineered mechanical structure with standard connections, enabling simple installation, convenient maintenance, and reliable long-term operation.
Durable construction with minimal moving parts, resulting in low maintenance requirements and reduced operating costs.
Bicolor Level Gauge-Applications
The bi color level gauge is ideal for industrial systems where precise and reliable liquid level monitoring is required. Its dual-color display allows operators to quickly distinguish between liquid and vapor phases, making it suitable for a wide range of demanding environments:
Chemical & Petrochemical Plants: Monitors corrosive or hazardous liquids in reactors, storage tanks, and process vessels with high visibility and safety.
Boilers & Steam Systems: Provides accurate water level indication in boiler drums and steam vessels, resistant to high temperatures and pressure fluctuations.
Water Treatment & Industrial Tanks: Ensures clear and continuous observation of water or process liquid levels in filtration, storage, and circulation systems.
Food & Pharmaceutical Processing: Supports sanitary and clean operations where precise level indication is critical for production quality.
Oil & Gas Storage & Transportation: Enables safe, real-time monitoring of tanks, pipelines, and fuel storage under varying operational conditions.
This gauge is particularly effective in applications involving high temperature, high pressure, or steam conditions, offering stable performance and clear visual feedback even under challenging industrial conditions.
Level Measuring Instruments Parameter
| Bi Color Level Gauge-Type | INBI113 |
| Medium | liquid or material that is generally or slightly corroded |
| Measuring Range | 5m, 10m, 15m, 30m, 50m, 60m,120m |
| Transducer Material | Ceramic |
| Measurement Error | 0.5%. 1.0% |
| Accuracy | ±3mm (no wave calm water surface) |
| Resolution | 3~5mm or 0.1% (take large value) |
| Display Mode | LCD, parameters can be set through the panel buttons |
| Signal Output | 4~20mADC |
| Relay Output | 2 groups are optional, and the relay status is programmable |
| Working Temperature | -25~80℃ |
| Communication Interface | RS232, RS485/Modbus |
| Electrical Interface | M20*1.5, 1/2″NPT |
| Explosion-proof Grade | ExiaIICT6Ga/ExdIICT6Gb |
| Protection level: | IP67 |
| Shell material: | engineering-plastics, aluminum alloy, SS304 |
| Ambient temperature: | (meter) -20-60℃; (sensor) -20~80℃ |
| Relative Humidity | 95% |
Instrava OEM/ODM
As your trusted supplier and sourcing partner, we bridge the gap between your custom requirements and China’s vast manufacturing capabilities.
Finding the right product in a massive supply chain can be challenging. That is where we step in.
As a curated industrial supplier, our core value is simple: we stand in your shoes to help you procure the most optimal products. Whether you are an EPC contractor needing specialized technical compliance, an OEM equipment manufacturer looking for custom branding, or an industrial distributor/trader seeking competitive edge, we customize and tailor products to fit your exact procurement needs.
For EPC Contractors & Engineers: We custom-configure instruments and devices to match your precise datasheets—tailoring process connections, exotic materials, signal protocols, and managing third-party calibration and testing so you get project-ready solutions.
For OEM Equipment Manufacturers: We provide comprehensive OEM/ODM customization, including custom housing, labeling, branding (private labeling), and tailored technical specifications to seamlessly integrate with your machinery.
For Industrial Distributors & Traders: We offer flexible customization in packaging, product ranges, and technical parameters, helping you differentiate your portfolio and win more local bids.
One-Stop Engineering Alignment: You don’t have to deal with multiple factories. We translate your technical requirements into precise manufacturer blueprints.
Strict Quality & Compliance Safeguard: We oversee the entire customization and production process in China, ensuring the final customized product meets your local standards and certifications.
Our Ultimate Value: We don’t just sell what’s on the shelf. We find, customize, and deliver the most suitable and cost-effective product for your unique application.
What is a bi color level gauge and how does it work?
A bi color level gauge, also called a sight glass level indicator, is a visual instrument for monitoring liquid levels in tanks and vessels. It uses dual-color optical technology to distinguish liquid (green) and vapor (red) phases, providing instant, real-time level observation without electrical power. This makes it ideal for chemical, boiler, and industrial process applications.
What types of bi color level gauges are available?
Bi color level gauges are available in transparent, reflex, and mirror-type configurations. Transparent gauges are best for clear liquids, reflex types improve visibility in steam or high-temperature systems, and mirror-type gauges enhance readability in low-light or medium-pressure vessels.
Which industries commonly use bi color level gauges?
Bi color level gauges are widely used in chemical, petrochemical, boiler, water treatment, food, pharmaceutical, and oil & gas industries. They are especially suitable for high-temperature, high-pressure, or steam conditions where reliable liquid level monitoring is critical for process safety and efficiency.
How should a bi color level gauge be installed and maintained?
The gauge should be installed via standard flanges or threaded connections to the vessel. Before operation, pressure testing is required. During use, valves should be opened gradually, and the gauge should be checked regularly for leaks. Contaminated glass can be safely cleaned after draining the medium and relieving pressure, ensuring long-term reliable performance.
How does the safety mechanism of a bi color level gauge work?
Most bi color level gauges feature a built-in safety steel ball. If the glass plate breaks or vapor/liquid pressure exceeds the rated threshold, the steel ball automatically seals the flow path. This prevents media leakage, protects personnel, and ensures safe operation in chemical, boiler, and industrial vessels.
How does a bi color level gauge perform under extreme temperature and pressure conditions?
Bi color level gauges are designed for high-temperature and high-pressure industrial applications. The dual-color optical system ensures clear visual differentiation between liquid and vapor phases, even under steam or superheated conditions. High-strength borosilicate or quartz glass and corrosion-resistant metal housings provide mechanical stability, while the built-in safety steel ball prevents media leakage if the glass is damaged, ensuring reliable and safe operation in demanding chemical, boiler, or industrial processes.
We select manufacturers from a neutral, impartial standpoint, always with your best interests in mind.
Our very existence depends on helping you source the products that are the perfect fit for your needs.
Based in China, we are able to conduct on-site inspections of production environments and product quality firsthand.
We help you avoid intermediaries posing as factories.
We facilitate smoother after-sales support, eliminating time zone issues and the delays often associated with dealing directly with factories.
Our multilingual team ensures effective communication.
For a trading startup, every interaction with a client is a precious opportunity—a sign that you are willing to place your trust in us and give us the chance to prove ourselves.
In the digital age, while information is easily accessible, misconceptions often cloud the trust between people.
Instrava relies entirely on trust; it is our core philosophy and the foundation of our existence in society. It is the fundamental basis for our long-term growth and our commitment to serving the community.
Please place your trust in us.
Submit your manufacturing requirements, and our team will get back to you with professional solutions within 24 hours.