Technical Specifications

FAQ

1. What is the main function of the 350800-01-180 Hazardous Gas Sensor?

The 350800-01-180 is designed for continuous detection of combustible gases in hazardous industrial environments. It uses a catalytic bead sensing element to detect gases such as methane and hydrogen and works together with the Bently Nevada 3500/63 Hazardous Gas Detection Monitor. The sensor detects changes in combustible gas concentration and produces a corresponding electrical response that can be processed by the monitoring module. This arrangement allows the 3500 system to provide continuous gas monitoring, alarm functions, and safety-related responses when hazardous gas concentrations increase.

2. Which gases can the 350800-01-180 detect?

The 350800 sensor is specified as a catalytic bead CH₄ and H₂ sensor. The catalytic bead is treated with a catalyst that promotes oxidation of combustible gas, while a reference bead provides compensation for environmental effects. When combustible gas reaches the sensing element, the oxidation process changes the temperature and resistance of the active bead. The resulting imbalance in the sensing bridge is proportional to the concentration of combustible gas and can be interpreted by the 3500/63 monitoring system.

3. How does the catalytic bead sensing principle work?

The sensor uses a catalytic bead and a reference bead configured as part of a Wheatstone bridge. The catalytic bead contains a catalyst that promotes oxidation when combustible gas reaches the sensing surface. This reaction raises the temperature of the active bead relative to the reference bead and changes its electrical resistance. The resulting bridge imbalance corresponds to the concentration of combustible gas. This signal is then processed by the 3500/63 Hazardous Gas Detection Monitor. Because the sensing element relies on catalytic oxidation, sensor condition and calibration are important for maintaining accurate gas detection.

4. What is the response time of the 350800-01-180?

The 350800 hazardous gas detection system has a specified step-change response performance of T50 ≤10 seconds, T60 ≤12 seconds, and T90 ≤30 seconds when exposed to a sudden 100% LEL gas concentration. These response characteristics allow the system to detect a significant increase in combustible gas concentration relatively quickly. Actual response in an installed system can also be affected by gas flow, sensor location, environmental conditions, and the way gas reaches the sensing element. Correct positioning of the sensor is therefore important when designing a hazardous gas detection system.

5. How often should the 350800-01-180 be calibrated?

Calibration requirements depend on the application, environmental conditions, operating history, and applicable site safety procedures. The sensor supports manual calibration using a gas flow rate of 0.5 L/min and remote calibration at 2.0 L/min when the appropriate remote calibration arrangement is used. Calibration should be performed using the specified calibration gas and the procedures established for the 3500/63 hazardous gas detection system. If sensor sensitivity decreases significantly, calibration may no longer be possible, which can indicate that the sensing element has become spent or poisoned and requires replacement.

6. What sensitivity should be expected from a new 350800 sensor?

The initial sensitivity of the sensor, as viewed through the 3500 verification screen, is specified as greater than 15 mV/%LEL. A sensor with sensitivity reduced below approximately 6 mV/%LEL will not calibrate correctly and may be considered spent or poisoned. Long-term sensitivity drift is specified at less than 2.5% of signal per month under the stated reference conditions. Monitoring sensor sensitivity during routine maintenance is therefore useful for identifying gradual degradation before the sensor becomes unable to perform a proper calibration.

7. Can the 350800-01-180 be calibrated remotely?

Yes. The 350800 sensor can be used with the Bently Nevada 350810 Remote Haz Gas Calibrator. This arrangement is particularly useful when the sensor is installed in a hazardous area, a confined location, or another position that is difficult or undesirable for maintenance personnel to access directly. The remote calibrator uses calibration gas to control the gas exposure at the sensor without requiring electronics at the calibrator itself. When remote calibration is used, the specified calibration flow rate is 2.0 L/min, and the complete installation should be configured according to the hazardous-area requirements of the system.

8. What should be checked if the 350800-01-180 fails calibration?

If the sensor cannot complete calibration, first check the calibration gas, gas flow rate, tubing, connections, and calibration procedure. For manual calibration, the specified flow rate is 0.5 L/min, while remote calibration uses 2.0 L/min. The sensor wiring and connection to the 3500/63 module should also be inspected. If the calibration setup is correct but the sensor sensitivity remains below the required level, the sensing element may be spent or poisoned. A sensitivity below approximately 6 mV/%LEL can prevent successful calibration. In this situation, replacing the sensor may be necessary rather than repeatedly attempting calibration.