Safety Hazard Prevention and Control in Centrifugal Pump Factories

Centrifugal pumps in factory operations involve potential safety hazards in mechanical, electrical, and medium leakage aspects, requiring strict prevention and control from dimensions such as operation, maintenance, and environment. The following are key safety hazards and prevention points worthy of attention:

I. Mechanical Operation Hazards: Risks from Rotating Parts and Vibration

1. Mechanical Injury from Impeller/Shaft

• Hazard:The impeller of a centrifugal pump rotates at high speed (usually over 2900 rpm). If the protective cover is missing, loose, or not locked, operators' limbs may be caught in the rotation, causing lacerations or fractures. For example, in a chemical plant, a worker suffered a comminuted fracture after their arm touched an operating impeller due to the protective cover not being reinstalled after maintenance.

• Prevention:

1. A fully enclosed metal protective cover must be equipped, fixed to the pump body with bolts, and operation without the cover is strictly prohibited.
2. Regularly inspect the fasteners of the protective cover and replace it immediately if deformation or cracks are found.

2. Secondary Risks Caused by Abnormal Vibration

• Hazard: Misalignment of the pump shaft, unbalanced impeller, or loose foundation can cause severe vibration, leading to loose bolts, pipeline rupture, or even pump body overturning. For instance, in a power plant, a centrifugal pump with worn bearings caused high-temperature steam leakage from the outlet pipeline flange due to vibration, scalding nearby personnel.
• Prevention:

1. Use a laser alignment tool to calibrate the shaft concentricity during installation, and fix the foundation bolts with secondary grouting.
2. Measure the vibration value of the bearing housing weekly with a vibration detector (allowable value ≤ 4.5 mm/s) and stop operation immediately for maintenance if the standard is exceeded.

II. Electrical and Explosion-Proof Hazards: Leakage and Spark Risks

1. Motor Electric Leakage and Electric Shock

• Hazard: When the motor insulation ages, the junction box is waterlogged, or the grounding is poor, the casing may carry mains voltage (220V/380V), causing electric shock if touched by operators. The risk of leakage is higher in humid environments (such as coal washing plants).
• Prevention:

1. The motor must be grounded (ground resistance ≤ 4Ω), and the winding insulation resistance should be tested monthly with an insulation meter (≥ 2MΩ).
2. The junction box must be sealed and waterproof, and outdoor pumps should be equipped with rain covers.

2. Spark Risks in Flammable and Explosive Environments

• Hazard: When transporting flammable media such as gasoline or ethanol, static electricity accumulation and discharge on the pump body, or a motor that does not meet explosion-proof standards (e.g., non-Ex certified), may ignite the vapor mixture. For example, in a refinery, an explosion occurred due to benzene leakage caused by sparking from a non-explosion-proof centrifugal pump motor during startup.
• Prevention:

1. Explosion-proof motors (explosion-proof grade ≥ Ex d IIB T4) must be used in explosive hazard areas (such as Zone 0 and Zone 1).
2. The pump body must discharge static electricity through a grounding wire (ground resistance ≤ 100Ω), and plastic pipes are prohibited for connection.

III. Medium Leakage and Toxic Hazards: Corrosion, Combustion, and Poisoning

1. Medium Leakage Caused by Seal Failure

• Hazard: Wear of mechanical seals, aging of O-rings, or cracks in the pump body can lead to medium leakage. If concentrated hydrochloric acid is transported, leakage will corrode equipment and personnel's skin; if liquefied petroleum gas is transported, leakage may cause combustion and explosion.
• Prevention:

1. Regularly inspect the pressure of the seal chamber (mechanical seals need to maintain 0.2-0.3MPa flushing fluid pressure).
2. When transporting strongly corrosive media, use fluoroplastic seal rings + Hastelloy pump bodies, and disassemble and inspect the seal surface wear every quarter (allowable wear ≤ 0.5mm).

2. Inhalation Risk of Toxic Media

• Hazard: When transporting toxic media such as aniline or formaldehyde, trace leakage of volatile gases inhaled may cause chronic poisoning of operators. For example, in a pesticide factory, a centrifugal pump seal leakage exposed workers to low-concentration organophosphate vapors for a long time, leading to nervous system damage.
• Prevention:

1. Install toxic gas alarms in the pump area (aniline alarm threshold ≤ 1ppm) and link them to the ventilation system.
2. Operators must wear gas masks (filter cartridges should match the media toxicity) and maintain a safe distance (≥ 1.5m) during patrols.

IV. Overpressure and Idling: Equipment Overload and Explosion Hazards

1. Overpressure Explosion Caused by Outlet Blockage

• Hazard: If the outlet valve is fully closed when starting the centrifugal pump, the liquid in the pump will heat up due to high-speed rotation, and the pressure can surge to 2-3 times the design pressure, causing the pump body to rupture. For example, in a chemical plant, an operator mistakenly closed the outlet valve, resulting in the centrifugal pump casing bursting, methanol splashing, and triggering a fire.
• Prevention:

1. The operation procedure specifies "open the inlet valve first, then start the motor, and then slowly open the outlet valve".
2. A safety valve must be installed on the outlet pipeline (set pressure to 1.1 times the working pressure) and calibrated annually.

2. Impeller Burning Caused by Idling

• Hazard: When the pump idles without medium, the impeller rubs against the pump casing, generating heat (temperature can reach over 300℃), which may burn the impeller or even ignite residual media. For example, in a wastewater treatment plant, due to low liquid level, the centrifugal pump idled for 30 minutes, causing the impeller to carbonize and smoke.
• Prevention:

1. Install a liquid level switch on the inlet pipeline, and interlock to stop the machine when the liquid level is lower than the minimum suction head (≥ 2m).
2. Open the exhaust valve before starting, and close the switch only after confirming that the pump body is full of medium.

V. High Temperature and Noise: Physical Injury Hazards

1. Scalding from High-Temperature Media

• Hazard: When transporting heat-conducting oil (temperature ≥ 200℃) or steam condensate, the pump body surface temperature is high, and operators touching it will suffer second-degree burns. For example, in a thermal power plant, the insulation layer of a centrifugal pump fell off, and a worker's arm touched the pump casing during patrol, resulting in large-area burns.
• Prevention:

1. The pump body and inlet/outlet pipelines must be wrapped with thermal insulation (surface temperature ≤ 50℃), fixed with aluminum sheets on the outer layer.
2. Set "No Touching" warning signs in high-temperature areas, and wear high-temperature-resistant gloves during patrols.

2. Hearing Damage Caused by Noise

• Hazard: The operating noise of centrifugal pumps usually reaches 85-100dB, and long-term exposure (8 hours per day) will cause permanent hearing loss. For example, in a mine concentrator without noise reduction measures, workers' hearing generally decreased by 20 decibels after 3 years of work.
• Prevention:

1. Install soundproof covers on the pump body (noise reduction ≥ 25dB) and mufflers at the motor fan.
2. Operators must wear earplugs (noise reduction value ≥ 30dB) and undergo regular hearing tests (once a year).

VI. Safety Blind Spots in Maintenance and Repair

1. Accidental Startup Caused by Unpowered and Unlabeled Equipment

• Hazard: Failing to cut off the motor power and lock the label during maintenance, and other personnel mistakenly closing the switch to start the equipment, which may cause injury to maintenance personnel by rotating parts. For example, when a fitter in a factory was repairing a centrifugal pump, an electrician mistakenly powered it on, causing a broken arm.
• Prevention:

1. Implement the "Lockout/Tagout" procedure (LOTO), lock the switch with a padlock after cutting off the power, and the key is kept by the maintenance personnel.
2. Use a multimeter to confirm that the motor has no voltage before maintenance, and mark "Under Maintenance" on the switch with chalk.

2. Chemical Injury Caused by Residual Media

• Hazard: Failing to replace the media in the pump before maintenance, residual strong acids, alkalis, or flammable liquids may burn the skin or explode when encountering open flame. For example, when disassembling a centrifugal pump in a chemical plant, residual ammonium nitrate solution came into contact with metal tools, generating sparks and causing an explosion.
• Prevention:

1. Replace the media in the pump with nitrogen before maintenance (oxygen content ≤ 1%), and detect the pH value of the residual liquid with pH test paper.
2. When working inside the pump body, wear protective clothing, goggles, and use copper tools (to avoid sparks).

VII. Environmental and Management Hazards: Poor Ventilation and Operation Errors

1. Asphyxiation Risk in Confined Spaces

• Hazard: When the pump is installed in a closed pump room or underground tank area, gases volatilized from medium leakage (such as carbon dioxide) may accumulate, causing the oxygen concentration to drop (< 19.5%), leading to personnel asphyxiation.
• Prevention:

1. The pump room must be equipped with a mechanical ventilation device (ventilation ≥ 12 times per hour) and an oxygen detector.
2. Before entering the underground pump area, use a gas detector to measure the oxygen content and wear a self-contained breathing apparatus after confirming safety.

2. Inadequate Training of Operators

• Hazard: Misoperation by untrained personnel (such as backflow startup, frequent start-stop) will accelerate equipment damage and cause safety accidents. For example, a new employee mistakenly fully opened the outlet valve of a concentrated sulfuric acid pump, leading to pipeline overpressure rupture.
• Prevention:

1. Operators must pass the centrifugal pump operation assessment (theory + practical) and work with a certificate.
2. Carry out emergency drills quarterly (such as leakage disposal, electric shock first aid) to improve risk response capabilities.

Conclusion

Teffiko always emphasizes that the safe operation of centrifugal pumps requires building a "technology + management + protection" trinity prevention and control system: from selecting explosion-proof and corrosion-resistant equipment hardware (such as Ex d IIC T6 explosion-proof motors, double-end mechanical seals) to deploying AI intelligent monitoring systems for fault early warning, and then implementing certified operation and emergency drills for operators, each link is the key to building a solid safety line. Teffiko suggests that enterprises regularly carry out equipment safety assessments, preferentially select centrifugal pumps in line with API 610 standards, and incorporate key parameters such as vibration and temperature into real-time monitoring networks through intelligent sensing technology. Only by taking technological innovation as the cornerstone and management norms as the guarantee can the safety accident risk of centrifugal pumps be minimized and a solid safety barrier be built for industrial production.