Why fire pumps burn their motors and what needs to be noted for the right choice.
Nov 18, 2022
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Water pumps burn the motor mainly for the following reasons.
Starting with a load can cause damage to the motor, the actual use of head is too much lower than the pump nameplate head; submersible pumps without water working time is too long.
First of all, first figure out the motor burn is burned bearing (mechanical failure) or burned coil (electrical failure).
If the fault is burned coil, mainly due to overcurrent, sometimes the voltage is too high or too low can also cause the coil to heat short circuit, so first check whether the voltage when running is too much different from the rated voltage.
Overcurrent short circuit, there may be several reasons.
.JPG)
Equipment overload operation, so that the motor runs at or over rated current for a long time. Special attention should be paid to the fact that the starting current of the motor is 3-5 times the rated current, so you should try to avoid starting the equipment with a load or running at full load (it mainly depends on the matching margin between the rated current of the motor and the normal running current)
The motor works in a more humid working environment. Before starting the motor, the insulation of the coils should be checked for ground and phase insulation, the insulation requirements are different for different voltage levels and can be checked with reference to the relevant national standards. During the operation of the motor, attention should be paid to the waterproofing and moisture-proofing of the motor.
The mechanical failure of the pump machine causes the motor to be overloaded, the current is too high and the coil is burnt.
The heat dissipation of the motor goes wrong. General motor coils are air-cooled shells, submersible pumps are water-cooled shells. Large motors mostly use air-air heat exchangers, air-water heat exchangers for cooling. If the cooling water (air) is broken, so that the coil can not dissipate heat, are likely to burn the coil.
.JPG)
The head of the centrifugal pump is used to overcome the height and resistance, high head of the pump in the high head point of work when his flow is the design point of the flow, if the work at low head, equivalent to the pump outlet resistance is reduced, when the flow of the centrifugal pump will increase, the motor will be overloaded, super to a certain extent will burn the motor. For example, the head of a water pump is 50 meters, the flow is 50 cubic meters / hour, when it to 50 meters high to give water, its flow is 50 cubic meters / hour, when it to 40 meters high to give water, its height and resistance to reduce its flow may reach 80-90 cubic meters / hour or more, then the motor will be hot or burned.
1、Correctly choose the working point of the fire pump. Each kind of pump has a certain working pressure range, such as: 2BV series water ring vacuum pump working pressure range 760mmHg ~ 25mmHg (absolute pressure), in such a wide pressure range, the pump pumping speed with the pressure and change (detailed changes refer to the pump performance curve), its stable working pressure range of 760 ~ 60mmHg. Therefore, the working point of the pump should be selected within this range More suitable, and can not let it in 25 ~ 30mmHg under long-term work.
2, the working pressure of the fire pump should meet the limit of fire fighting equipment and working pressure requirements. For example, if a vacuum drying process requires a working vacuum of 10mmHg, the ultimate vacuum of the selected vacuum pump should be at least 2mmHg, and it is better to reach 1mmHg. Usually the ultimate vacuum of the selected pump should be half to one order of magnitude higher than the working vacuum of the vacuum equipment.
3、The correct combination of fire pumps. Because the fire pump has selective pumping, therefore, sometimes choose one kind of pump can not meet the pumping requirements, need several pumps combined, complement each other to meet the pumping requirements. For example, the titanium sublimation pump has high pumping speed for hydrogen, but cannot pump helium, while the three-pole sputtering ion pump, (or two-pole asymmetric cathode sputtering ion pump) has a certain pumping speed for argon, the combination of the two, it will make the vacuum device to get a better vacuum. In addition, some vacuum pumps can not work under atmospheric pressure, need pre-vacuum; some vacuum pumps export pressure is lower than atmospheric pressure, need pre-stage pump, so all need to use the pump combination.
4、The fire pump should be able to discharge the whole amount of gas produced in the process of fire fighting equipment under its working pressure.
.JPG)
5, fire fighting equipment on the requirements of oil pollution. If the equipment strictly requires no oil, you should choose a variety of oil-free pumps, such as: water ring pumps, molecular sieve adsorption pumps, sputtering ion pumps, cryogenic pumps, etc.. If the requirements are not strict, you can choose to have oil pumps, plus some anti-oil pollution measures, such as adding cold traps, baffles, oil traps, etc., can also achieve clean firefighting requirements.
6、How about the influence of oil vapour discharged from the fire pump on the environment. If the environment does not allow pollution, you can choose an oil-free fire pump, or discharge the oil vapour to the outside.
7、Know the composition of the gas being pumped, whether the gas contains condensable vapour, whether there are particles of dust, whether there is corrosiveness, etc. When choosing a fire pump, you need to know the composition of the gas and choose the appropriate pump for the pumped gas. If the gas contains vapour, particles, and corrosive gases, you should consider installing auxiliary equipment such as condensers and dust collectors on the inlet pipeline of the pump.
8. The vibration generated by the fire pump has no effect on the process and the environment. If the process does not allow, a vibration-free pump should be selected or anti-vibration measures should be taken.
9、The price, operation and maintenance cost of the fire pump.
Starting with a load can cause damage to the motor, the actual use of head is too much lower than the pump nameplate head; submersible pumps without water working time is too long.
First of all, first figure out the motor burn is burned bearing (mechanical failure) or burned coil (electrical failure).
If the fault is burned coil, mainly due to overcurrent, sometimes the voltage is too high or too low can also cause the coil to heat short circuit, so first check whether the voltage when running is too much different from the rated voltage.
Overcurrent short circuit, there may be several reasons.
Equipment overload operation, so that the motor runs at or over rated current for a long time. Special attention should be paid to the fact that the starting current of the motor is 3-5 times the rated current, so you should try to avoid starting the equipment with a load or running at full load (it mainly depends on the matching margin between the rated current of the motor and the normal running current)
The motor works in a more humid working environment. Before starting the motor, the insulation of the coils should be checked for ground and phase insulation, the insulation requirements are different for different voltage levels and can be checked with reference to the relevant national standards. During the operation of the motor, attention should be paid to the waterproofing and moisture-proofing of the motor.
The mechanical failure of the pump machine causes the motor to be overloaded, the current is too high and the coil is burnt.
The heat dissipation of the motor goes wrong. General motor coils are air-cooled shells, submersible pumps are water-cooled shells. Large motors mostly use air-air heat exchangers, air-water heat exchangers for cooling. If the cooling water (air) is broken, so that the coil can not dissipate heat, are likely to burn the coil.
The head of the centrifugal pump is used to overcome the height and resistance, high head of the pump in the high head point of work when his flow is the design point of the flow, if the work at low head, equivalent to the pump outlet resistance is reduced, when the flow of the centrifugal pump will increase, the motor will be overloaded, super to a certain extent will burn the motor. For example, the head of a water pump is 50 meters, the flow is 50 cubic meters / hour, when it to 50 meters high to give water, its flow is 50 cubic meters / hour, when it to 40 meters high to give water, its height and resistance to reduce its flow may reach 80-90 cubic meters / hour or more, then the motor will be hot or burned.
1、Correctly choose the working point of the fire pump. Each kind of pump has a certain working pressure range, such as: 2BV series water ring vacuum pump working pressure range 760mmHg ~ 25mmHg (absolute pressure), in such a wide pressure range, the pump pumping speed with the pressure and change (detailed changes refer to the pump performance curve), its stable working pressure range of 760 ~ 60mmHg. Therefore, the working point of the pump should be selected within this range More suitable, and can not let it in 25 ~ 30mmHg under long-term work.
2, the working pressure of the fire pump should meet the limit of fire fighting equipment and working pressure requirements. For example, if a vacuum drying process requires a working vacuum of 10mmHg, the ultimate vacuum of the selected vacuum pump should be at least 2mmHg, and it is better to reach 1mmHg. Usually the ultimate vacuum of the selected pump should be half to one order of magnitude higher than the working vacuum of the vacuum equipment.
3、The correct combination of fire pumps. Because the fire pump has selective pumping, therefore, sometimes choose one kind of pump can not meet the pumping requirements, need several pumps combined, complement each other to meet the pumping requirements. For example, the titanium sublimation pump has high pumping speed for hydrogen, but cannot pump helium, while the three-pole sputtering ion pump, (or two-pole asymmetric cathode sputtering ion pump) has a certain pumping speed for argon, the combination of the two, it will make the vacuum device to get a better vacuum. In addition, some vacuum pumps can not work under atmospheric pressure, need pre-vacuum; some vacuum pumps export pressure is lower than atmospheric pressure, need pre-stage pump, so all need to use the pump combination.
4、The fire pump should be able to discharge the whole amount of gas produced in the process of fire fighting equipment under its working pressure.
5, fire fighting equipment on the requirements of oil pollution. If the equipment strictly requires no oil, you should choose a variety of oil-free pumps, such as: water ring pumps, molecular sieve adsorption pumps, sputtering ion pumps, cryogenic pumps, etc.. If the requirements are not strict, you can choose to have oil pumps, plus some anti-oil pollution measures, such as adding cold traps, baffles, oil traps, etc., can also achieve clean firefighting requirements.
6、How about the influence of oil vapour discharged from the fire pump on the environment. If the environment does not allow pollution, you can choose an oil-free fire pump, or discharge the oil vapour to the outside.
7、Know the composition of the gas being pumped, whether the gas contains condensable vapour, whether there are particles of dust, whether there is corrosiveness, etc. When choosing a fire pump, you need to know the composition of the gas and choose the appropriate pump for the pumped gas. If the gas contains vapour, particles, and corrosive gases, you should consider installing auxiliary equipment such as condensers and dust collectors on the inlet pipeline of the pump.
8. The vibration generated by the fire pump has no effect on the process and the environment. If the process does not allow, a vibration-free pump should be selected or anti-vibration measures should be taken.
9、The price, operation and maintenance cost of the fire pump.
