Common troubleshooting of fire pressure gauges: What to do if the pointer is stuck, leaking, or the scale is blurred?

1. Pointer stuck: unable to indicate pressure normally

Cause of fault

Internal mechanical damage: The gears, hairsprings, or spring tubes inside the pressure gauge are deformed or broken.

Impurity blockage: Rust, scale, or foreign matter in the pipeline enters the pressure gauge and jams the pointer mechanism.

Overpressure shock: The system pressure exceeds the range instantly (such as the water hammer effect), causing the mechanical parts to deform.

Potential risks

The inability to monitor the system pressure in real time may delay the start of the fire protection system or the fault alarm.

Misjudgment of the system status leads to safety hazards.

Solution

Tap the case: Tap the case with a rubber hammer to try to loosen the stuck pointer (temporary emergency only).

Disassembly and cleaning:

Close the valve, remove the gauge head after venting the pressure.

Clean up the internal impurities with alcohol or a special cleaner.

Replace a new gauge: If the internal gears or spring tubes are damaged, it is recommended to replace them directly (the repair cost may be higher than that of a new gauge).

2. Oil leakage (oil-immersed pressure gauge)

Cause of failure

Aging of the seal ring: After long-term use, the rubber seal ring hardens and cracks.

Case damage: External impact or corrosion causes cracks in the case.

Oil evaporation: High temperature environment causes silicone oil to gradually evaporate and the liquid level drops.

Potential risks

After oil leakage, the pointer damping fails, and the readings shake or are inaccurate.

Oil stains may contaminate fire pipes or equipment.

Solution

Replace the seal ring:

Remove the gauge head and replace the oil-resistant rubber seal ring (must match the original factory specifications).

Refill silicone oil:

Use high-viscosity silicone oil (such as DC200) and fill it to the standard liquid level through the oil filling hole.

Overall replacement: If the case is broken, a new gauge must be replaced (select a protection level of IP65 or above).

3. Blurred or faded scale

Cause of failure

Ultraviolet radiation: Long-term direct sunlight causes the dial printing to fade.

Chemical corrosion: Acid-base environment or detergent erodes the dial coating.

Water vapor penetration: The humid environment causes the dial to fog and mold.

Potential risks

It is difficult to accurately read the pressure value, affecting the operation judgment.

It may be mistaken for the dial to be damaged, resulting in unnecessary replacement.

Solution

Cleaning the dial:

Use a soft cloth dipped in alcohol to gently wipe to avoid scratches.

Replace the dial:

Contact the manufacturer to provide the same model dial (some pressure gauges support separate replacement).

Add a protective cover:

Install a UV-proof acrylic cover or metal sheath.

4. Other common faults

5. Daily maintenance and preventive measures for fire pressure gauges

 Inspection items

• Regular calibration (once every 6 months)

Calibration method

Close the valve: isolate the pressure gauge from the system and exhaust the residual pressure.

Connect the standard gauge: use a standard pressure gauge with higher accuracy (0.25 grade or above) to compare the readings.

Pressure test: gradually apply 25%, 50%, 75%, 100% of the range pressure and record the error.

Allowable error: ≤±2% of the range (such as 1.6MPa gauge, the error must be ≤0.032MPa).

Adjust or replace: If the error is out of tolerance, try to adjust; if it cannot be repaired, replace the new gauge.

Note

The calibration must be performed by a certified person and records must be kept.

The digital pressure gauge needs to check the status of the sensor and display simultaneously.

• Environmental protection measures

Temperature and humidity

Avoid high temperature: ambient temperature ≤60℃ (high temperature will accelerate the volatilization of silicone oil or the aging of mechanical parts).

Moisture and condensation prevention: use a stainless steel shell (such as 316L material) or install a moisture-proof cover in humid places.

UV and corrosion

Shading treatment: add metal sheath or UV protection cover when installing outdoors.

Anti-corrosion selection: acid-resistant and alkali-resistant coating or all-stainless steel pressure gauges are selected in chemical areas.

Vibration and shock

Shock-absorbing installation: rubber pads or pulse dampers are installed in locations with large vibrations such as pump rooms.

Shock-resistant pressure gauges: oil-filled (glycerol or silicone oil buffer) or spring tube reinforced types are preferred.

• Installation specifications (preventive maintenance)

Installation location

Easy to observe: installation height 1.5-1.8 meters, avoid dead angles.

Avoid interference: avoid electromagnetic equipment (such as frequency converters), high-temperature pipes or corrosion sources.

Connection method

Buffer device: install a buffer tube ("S" bend) or throttle valve after the pump outlet or valve.

Isolation valve: install a three-way valve or needle valve for easy disassembly and maintenance.