【Q&A Question 212】2018.08.06

Reasons: (1) The packing was installed too tightly, causing overheating and smoking, which in turn ignited the oil vapor accumulated in the pump room. (2) The oil pump ran idle, resulting in high temperatures in the pump casing. (3) Air bubbles were present in the centrifugal pump’s ducts, causing violent vibrations in those ducts; this could even lead to the ducts breaking, allowing oil to leak out and catch fire. (4) The resistance of the static electricity conductors was too high (>100 ohms) or the conductors were broken and no longer functional. (5) Non-explosion-proof motors, electrical devices, and lighting fixtures were used, resulting in electric leakage and sparks. (6) Impact from metal objects or stray sparks.

Leakages at various sealing points of the hot oil pump; leaks in the cold oil pump caused by static electricity, sparks, or open flames

Seal leakage； The medium temperature is high; fire and combustion occur after a leak of the medium ； Deliberate destruction ；

Leak in the presence of an open flame (or sparks)

Reasons: (1) The packing was installed too tightly, causing overheating and smoking, which in turn ignited the oil vapor accumulated in the pump room. (2) The oil pump ran idle, resulting in high temperatures in the pump casing. (3) Air bubbles were present in the centrifugal pump’s ducts, causing violent vibrations in those ducts; this could even lead to the ducts breaking, allowing oil to leak out and catch fire. (4) The resistance of the static electricity conductors was too high (>100 ohms) or the conductors were broken and no longer functional. (5) Non-explosion-proof motors, electrical devices, and lighting fixtures were used, resulting in electric leakage and sparks. (6) Impact from metal objects or stray sparks.

1. Mechanical seal leakage； 2. Pump casing leakage

The following are the reasons for fires in oil pumps: (1) The packing is installed too tightly, causing it to overheat and smoke, which in turn ignites the oil vapor accumulated in the pump room. (2) The oil pump runs idle, causing the pump casing to overheat and igniting oil vapor. (3) Air pockets are present in the centrifugal pump pipeline, causing the pipeline to vibrate violently or even break, leading to oil leakage that can catch fire. (4) The resistance of the electrostatic wire is too high (greater than 100 ohms), or the wire is broken and non-functional. (5) Use non-explosion-proof electrical appliances. Arcing due to leakage current. (6) Sparking by striking iron. (7) The design materials of the oil pump are inappropriate and cannot withstand high temperatures. The oil pump inlet and outlet pipelines caught fire due to rupture caused by long-term erosion or corrosion. (8) An unreasonable selection of equipment – such as the use of mechanical seals, a cooling system, static electricity grounding, and explosion-proof motors – can help reduce the risk of fires occurring in oil pumps. (9) If it is high-temperature heavy oil, a leak can cause it to catch fire on its own; for example, in the case of a sealed leak ； A low amount of cooling water or a long interruption in its supply can cause the pump’s temperature to rise too high, leading to seal damage and subsequent fires, and so on

(1) The packing was installed too tightly, causing it to overheat and smoke, which in turn ignited the oil vapor accumulated in the pump room. (2) The oil pump runs idle, causing the pump casing to overheat and igniting oil vapor. (3) Air pockets are present in the centrifugal pump pipeline, causing the pipeline to vibrate violently or even break, leading to oil leakage that can catch fire. (4) The resistance of the electrostatic wire is too high (greater than 100 ohms), or the wire is broken and non-functional. (5) Use non-explosion-proof electrical appliances. Arcing due to leakage current. (6) Sparking by striking iron. (7) The design materials of the oil pump are inappropriate and cannot withstand high temperatures. (8) An unreasonable selection of equipment can increase the risk of fire in oil pumps; this risk can be reduced by using mechanical seals with cooling systems, implementing static electricity grounding, and selecting explosion-proof motors. (9) If it is high-temperature heavy oil, a leak can cause spontaneous combustion; for example, in the case of a seal leak ； A low amount of cooling water or a long interruption in its supply can cause the pump’s temperature to rise too high, leading to damaged seals and subsequent fires, among other issues

(1) The packing was installed too tightly, causing overheating and smoking, which in turn ignited the oil vapor accumulated in the pump room. (2) Idling of the oil pump causes excessive temperature in the pump casing ； (3) Excessively high resistance of the electrostatic wire or the wire is broken and non-functional ； (4) Impact by iron tools or external fire sources.

Fires are likely to occur when the oil pump motor cannot be properly maintained or is used for an extended period of time. To prevent fires in electric motors, it is first necessary to understand the potential hazards that cause such fires. As for the motor itself, there are several reasons for a motor fire. 1. Internal short circuit: When the windings become damp, the insulation ages, overvoltage causes breakdown, or mechanical damage occurs, the insulation can be damaged, leading to short circuits between phases, between turns, or to ground. This results in a sharp rise in the motor’s temperature, and may even cause arcing and discharge, which can lead to fires. 2. Operation with a missing phase: When a three-phase asynchronous motor operates with a missing phase, under rated load its current increases to 1.73 times the rated value ； The starting current of the motor when started under locked-rotor conditions is 4 to 7 times the rated value. The above time period is too long; the windings will burn out and catch fire due to overheating. 3. Frequent starting: Each time the motor starts, it is subjected to the impact of stall current; if it starts multiple times in a short period of time, the windings can catch fire due to the rapid rise in temperature. 4. Poor contact: When the internal and external wiring of the motor becomes loose, resulting in poor contact, the contact resistance increases, which causes the connections to overheat; in severe cases, arcing can occur, leading to the burning of the winding insulation as well as any flammable materials in the vicinity. 5. Core short circuit: Due to poor quality or manufacturing defects, the motor core may experience a short circuit, which leads to a significant increase in eddy current losses and overheating of the core, thereby causing the motor to catch fire. 6. Mechanical lock-up: When the motor is installed improperly or foreign objects get inside it, or when the bearing lubrication is insufficient or contaminated, the rotor can get stuck; similarly, if the machinery driven by the motor gets stuck, this can cause the current flowing through the motor to increase sharply, leading to an excessive rise in the temperature of the windings and eventual fire. 7. Poor heat dissipation or high ambient temperature: If the motor’s external fan is not installed or is damaged, or if the ambient temperature exceeds 40°C, it can cause the motor to overheat severely, leading to the burning of its windings. 8. Severe overload: When a hydraulic motor is severely overloaded or operates under overload conditions for an extended period, or when a motor designed for intermittent operation is used for continuous use, the high temperatures generated can cause the insulation of the windings to burn out. 9. Poor maintenance: When the routine maintenance of the motor is not properly carried out, and problems are not addressed in a timely manner but left unattended, such as dust and debris blocking the ventilation slots, dirty or loose connections, or foreign objects falling into the motor, these issues must be cleaned up promptly; otherwise, they will affect the proper functioning of the motor and lead to overheating of the windings and even fire.