Low Water Level:

• Low water level risks overheating of boiler tubes, leading to tube failure. The low water level sensor detects this condition. The sensor signals the master controller, which activates the relay unit, ultimately shutting off the fuel solenoid valve, stopping fuel supply to the burners. A low-low water level triggers a complete boiler trip.

High Steam Pressure:

• High steam pressure exceeds the boiler's design limits, risking rupture of the steam drum or safety valve failure. The high-pressure switch senses the overpressure. The signal from the switch to the master controller triggers the fuel shutoff via the relay unit and solenoid valve. The boiler will also trip at the high-high pressure level.

Air Failure:

• Insufficient air leads to incomplete combustion, resulting in the production of harmful gases, unburnt fuel build-up and a potential boiler backfire or explosion. The air failure sensor detects insufficient airflow. It signals the master controller, activating the relay and solenoid valve, halting fuel flow.

Flame Failure:

• If the flame goes out, fuel continues to flow into the burner, creating a dangerous situation with the possibility of fuel buildup and explosion. The flame failure sensor detects the absence of a flame. This signal is sent to the master controller to shut off the fuel via the relay unit and solenoid valve.

Water Level Alarms (Low and High):

• Low-Level Test: Close the steam valve (1) and water valve (2), then open the drain valve (3). As the water level drops, the low-level alarm should activate, and the boiler should trip at the low-low water level.
• High-Level Test: Close the drain valve (3) and keep the steam valve (1) closed. Open the water valve (2) to raise the water level. The high-level alarm should sound when the high-level is reached, and the boiler will trip at the high-high level.

Steam Pressure Alarm:

• The steam pressure switch setting is adjusted to a lower pressure than normal operating pressure. This will trigger the high-pressure alarm and a boiler trip.

Flame Failure Alarm:

• The boiler is started. Then, the flame sensor (flame eye) is temporarily removed or obstructed. This simulates a flame failure, activating the alarm and causing a boiler trip. Remember to restore the flame sensor immediately after testing.