Challenging the Limits: A Comprehensive Guide to Gas Safety Monitoring in High-Temperature Furnaces and Industrial Ovens

In the field of industrial manufacturing, high-temperature furnaces and industrial ovens are core equipment for processes such as powder coating, metal heat treatment, composite material curing, and food processing. However, during the operation of these devices, solvents, adhesives, or organic components in the raw materials undergo thermal decomposition under high-temperature baking, releasing large amounts of flammable and explosive combustible gases.

When these gases accumulate in closed or semi-closed oven spaces, once the concentration reaches the explosion limit, it is extremely easy to trigger devastating fire or explosion accidents under the catalysis of the high-temperature environment, which serves as a natural "ignition point." How can reliable gas monitoring be achieved in such extreme high-temperature environments? Nexisense reveals the "protective shield" for industrial high-temperature environments.

The Threat of Combustion: Safety Hazard Analysis in High-Temperature Environments

As is well known, the occurrence of combustion requires the fulfillment of the "three elements": combustibles, an oxidant (oxygen), and an ignition point. Inside a high-temperature furnace, these three conditions are often on the edge of a dangerous balance:

1. High-concentration combustibles: Volatile organic compounds (VOCs) or hydrocarbon gases released by raw materials decomposing at high temperatures.

2. High-temperature trigger points: Electrical heating elements, gas nozzles, or the high-temperature inner walls of the oven itself provide excitation energy far exceeding that of a room-temperature environment.

3. Accumulation risk: If the ventilation system has insufficient air volume or fails, combustible gases will quickly accumulate at the top or in corners of the oven, and the concentration can instantly break through the Lower Explosive Limit (LEL).

Therefore, in the high-temperature furnace and oven industry, real-time monitoring of combustible gas concentrations and the implementation of automated linkage warnings are the "lifeline" for safe production in enterprises.

Nexisense High-Temperature Resistant Gas Detection Technology: Breaking the Temperature Shackles

Traditional general-purpose gas detectors can usually only work between -40°C and +70°C. Once they enter a high-temperature furnace exceeding 100°C, ordinary sensors will quickly experience thermal drift or even suffer physical damage.

SGA-500 Series Online High-Temperature Resistant Combustible Gas Detector

To address this technical pain point, Nexisense has developed the SGA-500 series high-temperature resistant specialized detection system. Its core advantages lie in:

• Original imported high-temperature resistant sensors: The core sensing components use special packaging processes and heat-resistant materials, enabling them to capture gas molecules directly in extreme environments without relying on external cooling systems.

• 250°C extreme endurance: Through Nexisense's secondary development and circuit optimization, this device can support continuous and stable operation in high-temperature environments up to 250°C with accurate data output.

• Split design with high-temperature extension line: Equipped with an 80cm specialized high-temperature resistant extension line. The ingenuity of this design allows the high-sensitivity sensor probe to penetrate deep into the core area of the oven while installing the processing transmitter in an external low-temperature zone, protecting electronic components while ensuring instantaneous detection.

• Industrial-grade explosion-proof and reliability: The entire unit has passed strict explosion-proof certification, and the circuit has undergone signal amplification and anti-interference optimization to effectively filter out electromagnetic noise at industrial sites.

  
  

Smart Monitoring: From Single Alarms to System Linkage

Nexisense provides not just an instrument, but a complete automated safety logic.

1. Automatic Alarms and Pre-warnings

When the combustible gas concentration in the oven is detected to reach 25% LEL (low alarm), the system automatically starts the sound and light alarm and forces an increase in the ventilation fan speed; when it reaches 50% LEL (high alarm), the system can immediately cut off the heating power supply to prevent the accident from escalating.

2. Remote Data Transmission

Supports 4-20mA analog signal or RS485 Modbus RTU digital signal output. Data can be transmitted in real-time to the PLC or DCS system in the central control room, allowing O&M personnel to master the safety status of high-temperature ovens across the plant from a large screen.

3. Multi-point Coverage Strategy

For large coating assembly lines or tunnel furnaces, Nexisense recommends placing points at the feed inlet, discharge outlet, and internal exhaust branch pipes to achieve full-scale risk coverage.

Why Choose Nexisense High-Temperature Solutions?

• Excellent Stability: After long-term high-temperature aging tests, the sensor's zero drift in high-temperature environments is extremely small.

• Rapid Response: The specially designed gas chamber structure ensures fast gas diffusion, with a response time of T90 < 20s.

• Convenient Maintenance: The split design allows for the replacement of the sensor probe without disassembling the entire unit, greatly shortening maintenance downtime.

• Customized Service: Material selection can be matched according to the customer's specific oven temperature (e.g., 150°C, 200°C, or 250°C).

To meet the professional technical needs of the high-temperature industrial field, the following is the FAQ section deeply optimized for Nexisense high-temperature furnace and industrial oven gas detection solutions. This part focuses on the identification of thermal decomposition products, sensor thermal drift handling, explosion-proof linkage logic, and lifespan maintenance under complex working conditions.

High-Temperature Baking Environment Gas Monitoring: In-Depth Analysis and Frequently Asked Questions (FAQ)

Q1: Why is monitoring LEL (Lower Explosive Limit) in high-temperature ovens more urgent than in room-temperature environments?

A1: According to physicochemical principles, the Lower Explosive Limit (LEL) of combustible gases decreases as temperature rises. This means that inside a 200°C oven, the concentration of solvent vapor required for an explosion is lower than at room temperature. Furthermore, high temperature itself is close to the auto-ignition point of many organic solvents. Nexisense's high-temperature resistant detectors can capture minute concentration fluctuations before danger occurs, triggering ventilation linkage before the gas reaches its thermal auto-ignition point, nipping accidents in the bud.

Q2: How does the SGA-500 series overcome the common "thermal drift" phenomenon of sensors in high-temperature environments?

A2: Thermal drift is the main cause of unstable sensor output in environments with large temperature differences. Nexisense adopts a three-level temperature control and compensation mechanism: first, special high-temperature resistant catalytic elements are selected, whose physical structure remains highly stable during thermal expansion and contraction; second, the transmitter has a built-in high-precision temperature sensor to correct zero point and sensitivity offsets caused by temperature in real-time via algorithms; finally, the circuit board is installed separately, ensuring electronic components work in a low-temperature zone, eliminating electromagnetic interference from environmental heat on the processing circuit at the source.

Q3: In coating drying furnaces, will the generated paint mist and resin volatiles clog the high-temperature resistant probe?

A3: This is a typical pain point in the high-temperature baking industry. Nexisense's high-temperature resistant probe comes standard with a double-layer stainless steel powder metallurgy sintered filter element. This structure allows gas molecules to diffuse freely into the sensing chamber while effectively blocking large particles of paint mist and viscous resin deposits. Regarding maintenance, we recommend periodic cleaning of the filter element with industrial solvents or using compressed air for back-blowing to restore the probe's permeability.

Q4: What are the technical requirements for installing the 80cm high-temperature resistant extension line?

A4: During installation, ensure the sensor probe is located at the "return air outlet" of the oven's air circulation or at top dead corners where gases easily accumulate, while the transmitter host should be installed on the outer wall of the oven where the temperature difference is small. The extension line provided by Nexisense is wrapped in high-strength stainless steel braided mesh and a fluoroplastic insulation layer. During installation, avoid running it parallel with high-voltage cables to prevent electromagnetic coupling interference in high-temperature environments.

Q5: If my oven involves silane or silicon-containing materials, will it affect the sensor?

A5: This is a very professional safety question. Silicon-containing compounds decompose at high temperatures to produce silicon dioxide, which forms a "glass-like" film on the surface of catalytic combustion sensors, leading to sensor "poisoning" and failure. For such working conditions, Nexisense recommends using high-temperature resistant Non-Dispersive Infrared (NDIR) sensors. The infrared principle is a non-contact measurement, unaffected by silicon poisoning, and can still accurately monitor combustible gas concentrations in oxygen-deficient environments.

Q6: How does the system's relay alarm output achieve multi-level safety protection?

A6: Nexisense recommends a dual-level linkage logic:

• Level 1 Alarm (e.g., 20% LEL): Relay closes, forcing the start of the oven's top fresh air supply fan and exhaust fan to reduce concentration.

• Level 2 Alarm (e.g., 50% LEL): Relay opens, directly cutting off the heating tube power supply or closing the gas proportional valve, and triggering the emergency shutdown program of the workshop's central control system to ensure the equipment enters a safe state.

Q7: Is the diffusion type or pump-suction type better for the sampling method of high-temperature detectors?

A7: For environments within 250°C, Nexisense recommends using the diffusion type (with extension line), which has a simple and reliable structure, no pump-wearing parts, and low maintenance. If the oven is under negative pressure or the temperature exceeds 250°C, a pump-suction sampling scheme is required, cooperating with a specialized high-temperature resistant sampling pump and metal cooling sampling tubes to lead the sample gas out of the furnace for cooling before detection.

Q8: How to determine if a high-temperature resistant detector has failed and needs replacement?

A8: Users can observe via the Nexisense transmitter's "Self-diagnosis Report":

• Sensitivity attenuation: During calibration, if it is found that extreme gain is required to compensate the indicated value, it means the sensor activity has declined.

• Response time: If the time for the reading to rise to 90% after introducing standard gas significantly exceeds 30 seconds, it is usually a signal of filter element clogging or sensor aging.

• Alarm self-check: Use the remote control monthly to simulate an alarm output, ensuring the back-end linkage devices (fans, valves) respond normally.

Summary

Safety monitoring of high-temperature furnaces and industrial ovens is a precision technical task that must account for multiple factors such as extreme temperature endurance, chemical poisoning, thermal drift, and explosion-proof linkage. With the SGA-500 series high-temperature resistant combustible gas detector, Nexisense provides customers with a safety guarantee system that can both operate stably in "intense heat" and "make a final decision" at critical dangerous moments.

Are there safety blind spots in your high-temperature equipment? Contact Nexisense technical engineers, and we will provide you with one-stop technical consultation from heat treatment process analysis to sensor selection and installation wiring, guarding your production line far away from explosion risks.