Greetings! Today our fuel pressure sensor on the boiler failed. We found out about this as a result of the malfunction of the boiler and the alarm “Abnormal fire” on the panel. This problem is quite critical and requires an immediate solution.
According to the instructions, the pressure in the line to the fuel spray nozzles should be about 20 kg, the pressure switch setting should be about 14 kg (low pressure protection).
Below I propose to figure out what this problem is and what it can lead to in the future.
What is an abnormal fire?
When the pressure switch is triggered, the fuel supply is cut off and the boiler stops. If this does not happen, then at low pressure in the line (14 kg and below), the fuel will not be immediately cut off, but will be incorrectly sprayed (poured) into the firebox and “torn” pieces of flame will form. For this reason, the "Abnormal fire" alarm will sound and the boiler will stop.
Another problem may arise if the burner has nozzles without non-return valves; in such situation, if the pressure switch is not working, small amount of fuel will leak to the boiler furnace, which can lead to fire and flame pops.
.JPG "Old pressure switch (calibration attempt)")
This problem was discovered as a result of the “Abnormal fire” alarm, which is a general alarm and the engineer on duty for a long time could not understand what the “wrong flame” problem was. This could be a lack or, on the contrary, a large amount of air supplied to the nozzles, it could be a problem with the photocell, temperature or fuel pressure (but there is no low pressure alarm and at the same time the engineer did not pay attention to the pressure gauge, which already had insufficient pressure).
Low fuel pressure protection helps the engineer quickly understand the problem, but even if it does not work, there is still the end protection for the “wrong flame” in the boiler furnace.
As a result, it was not possible to restore the old pressure switch, and calibration also did not help. Therefore, I had to replace the pressure switch with a new one. The pressure setting according to the instructions should be 14 kg and the differential should be about 1 kg.
After installing a new pressure switch, the low fuel pressure protection was tested with a positive result.
The fuel pressure switch on a boiler is a crucial safety device designed to monitor the pressure of the fuel being supplied to the boiler. Its primary function is to ensure that the fuel pressure stays within safe and efficient operating limits. Here's an overview of how it works and its importance:
Function and Operation
- Monitoring Pressure: The fuel pressure switch continuously monitors the fuel pressure in the system.
- Activation: If the fuel pressure falls outside the pre-set safe range (either too high or too low), the switch activates.
- Safety Response: Upon activation, the switch can trigger various safety mechanisms:
- Shutting Down the Boiler: This prevents the boiler from operating under unsafe conditions, reducing the risk of damage or accidents.
- Alerting Operators: It may trigger alarms or alerts to notify maintenance personnel of the issue.
Importance
- Safety: Maintaining the correct fuel pressure is critical to preventing dangerous situations such as explosions, fires, or equipment damage.
- Efficiency: Correct fuel pressure ensures the boiler operates efficiently, providing optimal combustion and heat generation.
- Maintenance: Early detection of pressure issues can help in diagnosing and addressing potential problems before they escalate, leading to more effective maintenance and longer equipment lifespan.
Types of Fuel Pressure Switches
- Low-Pressure Switches: These are designed to shut off the boiler if the fuel pressure drops too low, preventing inefficient combustion or potential flameouts.
- High-Pressure Switches: These switches shut off the boiler if the fuel pressure is too high, protecting the system from overpressure conditions that could damage components or create hazardous situations.
Installation and Maintenance
- Proper Installation: Ensure the switch is correctly installed according to the manufacturer’s guidelines and boiler specifications.
- Regular Testing: Periodically test the switch to verify it is functioning correctly. This can involve simulating pressure changes and observing the switch’s response.
- Routine Inspections: Regularly inspect the fuel lines, pressure switch, and associated components for signs of wear, damage, or blockages.
Troubleshooting Common Issues
- False Tripping: If the switch trips without a genuine pressure issue, check for electrical faults, sensor malfunctions, or incorrect pressure settings.
- No Response: If the switch does not activate under unsafe conditions, inspect the switch and wiring for faults, and verify the pressure sensor is functioning correctly.
- Calibration: Ensure the switch is calibrated to the correct pressure settings for your specific boiler model and fuel type.
Understanding and maintaining the fuel pressure switch is essential for the safe and efficient operation of a boiler system. Regular checks and proper maintenance can help prevent accidents and ensure reliable performance.
Boiler model: Miura GK-2230-1400.
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