Vacuum freeze-drying machine breakdown maintenance
  (A) failure of refrigerator
   1 The motor does not start up
    ① Power nowhere, the voltage is too low, too low starting voltage regulator (buck starts with a device), the thermal relay is still wood reset pressure switch contact is not closed, pressure is not reset after tripping relay contact , will not start bit cooler. At this point simply press the specification requirements, the power-on, the voltage is normal, so that the contacts can be reset.
    ② motor windings burned or inter-turn short circuit, such as on the power switch, causing the fuse blows, and other electrical circuit had no problems, it may be burned or turn the motor coil shorted.
    ③ transformer, relay, contactor coil burned or contacts being exposed, can cause the fuse has blown.
    2 motor not drag motor itself is no fault, because the load is too large refrigerator, far exceeding the rated power of the motor, resulting in compressor does not run or run significantly slower, and motor issued a "buzzing" sound, you should immediately turn off check out the power, first check whether the two phases have electricity, the supply voltage is normal. If the motor circuit without trouble, for the cooling systems.
    ① Compressor "bite evil" or "put evil." Its phenomena are hand drive flywheel or coupling (open type compressor), the compressor will not turn or rotate slightly stopped, this time should be disassembled compressor overhaul.
    ② motor drag is very difficult, speed is reduced, after stopping the flywheel or coupling plate moving, feeling significantly the severity of the points. When the disc to the most important position, as long as a relaxation, the flywheel will quickly reverse bounce around a half circle, indicating that there is a cylinder valve plate with severe leak. This time should be the lightest flywheel position to restart the motor, if you can drag the edge of running out inspection, normally to be confirmed only after put into use. If not drag or the motor must have "buzzing" sound, remove the valve plate for maintenance.
    3 chillers in operation a sudden stop if the power supply circuit is normal, and refrigerator in operation a sudden stop, it may be one of the following situations.
    ① suction pressure is too low, the low pressure cut off the power relay and parking. Suction pressure is too low will be consumed while the refrigerator is not cooling power and increase the amount of oil on the compressor, and even burn the motor. Reason causing low pressure system is generally poor in a partial obstruction, or lack of refrigerant.
    ② exhaust pressure is too high, the high-pressure relay and parking. Generate high discharge pressure of reasons: lack of cooling water or excessive temperature; water regulating valve failure; condenser fouling too thick; system components within the non-condensable gases; refrigerant perfusion too / left of the condenser condensing area; exhaust pipe and condenser pipe is not blocked and so on.
    ③ low oil pressure, turn off the power of the hydraulic relay and parking.
    ① motor overload, making installation of AC contactor or motor windings under thermal relay function at work, or a fuse blown surface parking.
    Since lyophilization process, especially during the first phase of drying, water vapor condenser refrigeration systems are generally not stop, otherwise the product will melt scrap. Therefore, the operator should always check whether the machine is operating normally. Eliminate the fault before they occur.
     4 cooling capacity is insufficient or no cold
    ① expansion valve opening is too large, then the shelf or a vapor condenser temperature drop is less than the set value, the compressor severe frost
    ② expansion valve opening is too small, then the temperature does not drop Ah go, but the compressor is hot. Suction valve at no frost.
    ③ insufficient refrigerant charge slip, then the temperature does not drop down, stoves low suction pressure, suction valve at no frost.
④ poor cooling system blockage, such as filtering hides clogged valves open late, solenoid valve failure, expansion valve blockage.
    ⑤ compressor valve plate portion or the lower part of the cylinder liner paper pad hit in Finland or rupture, or compressor suction and exhaust valve broken.
     3 heating system failure
    ① Direct thermal resistance wire break, resulting in energy plus does not go up.
    ② Ask thermal electric heater off, inadequate flow of circulating conveying fluid pump, the pump can not work normally hall, pipe blockage, insufficient heat carrying fluid, etc., can be added so that the heat does not go up.
    ③ Select the infusion pump design flow is too small, the head too high heat pipe diameter improperly, will not get the energy plus
    ④ original fault the material can overheat thermostat.
    4 water catching performance deterioration
    In addition to the refrigeration system cooling capacity decline, there may be for the following reasons
    ① vapor condenser defrost is not complete, so that the heat transfer performance deteriorated.
    ② product loading exceeds the specified value, or drying the water too much.
    ③ oven sublimation, excessive heat, excessive sublimation.
    5 Temperature, vacuum measurement error
    ① Select the table when designing the type and accuracy of unreasonable, for example, resistance thermometers with motivation Thermometer, hysteresis, serious, and when reading is 20 ℃, the actual temperature has exceeded 25 ℃
    ② Use the environment and adapt to the environment is not the same instrument such as thermocouple leads and connectors of different materials, is the main cause reading errors.
    ③ Some freeze-drying equipment used on Maxwell vacuum measurement, the measured vacuum of non-condensable gas partial pressure. Some freeze-drying equipment used on resistive vacuum gauge, the measured total pressure. Both on the same device measured the degree of vacuum is not asking to be normal.
④ Resistance to environmental temperature gauge, placed in different parts of the vacuum freeze-drying machine will be not the same degree of vacuum, the error caused by the temperature change is not conclusive quantitative relationship.

 

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