DPD-3 Thermal Conduction Vacuum Dryer  
Issues > Check/Troubleshooting
Vacuum Alarm is displayed on the Alarm Screen.
  1. Vacuum pump not functioning normally.
  2. The discharge plate at the bottom of the drying hopper is not closed securely.
  3. The discharge valve is not functioning (closing) normally.
  4. The open valve is not functioning (closing) normally.
  5. The plug in the lower part of the air filter is not closed securely.
  6. Air leak on the vacuum air route.
  7. Vacuum pressure switch is not working properly.

1. Vacuum pump not functioning normally.
  1. Vacuum pump not functioning normally.
  2. If either is occuring, the vacuum pump is defective. Either replace the pump or contact the local Matsui service office.
If problem persists
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2. The discharge plate at the bottom of the drying hopper is not closed securely.
The discharge plate at the bottom of the drying hopper is not closed securely.
  1. Check the discharge plate and O-ring.
  2. Close the discharge plate securely. If the O-ring has fallen off or is worn, either put the ring back or replace.
How to discharge material from the drying hopper
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3. The discharge valve is not functioning (closing) normally.
If material is clogging and the valve is not completely closed, an air leak will cause the vacuum alarm to start.
  1. Check the condition of the valve. Especially during use of mixed materials of granulating materials, check to see if particles or spool runner parts are caught or not.

    [Point] Use extra caution to avoid scratching the seal of the valve.
    [Point] If the spool runner parts are long, break part down twice.

  2. If material is caught, clean the valve. Also, if material is clogging the valve, adjust the secondary convey blow time and the secondary convey air. If the valve (solenoid valve) is damaged, repair or replace.
How to clean the discharge valve
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4. The open valve is not functioning (closing) normally.
If the open valve is not completely closed, an air leak will start the vacuum alarm.
  1. Check the condition of the open valve (solenoid valve).
  2. Repair or replace the open valve (solenoid valve).
If problem persists
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5. The plug in the lower part of the air filter is not closed securely.
If the plug is not completely closed, an air leak will start the vacuum alarm.
  1. If the plug is not completely closed, an air leak will start the vacuum alarm.
If problem persists
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6. Air leak on the vacuum air route.
  1. Check the vacuum pipings and drying hopper conditions. Please repair if there is an air leak. If the packing is badly worn, please replace.
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7. Vacuum pressure switch is not working properly.
If the switch, which checks the vacuum pressure, is not functioning normally, the vacuum alarm will light up even if the pressure is within the specified range.
  1. Check to see if the switch is functioning at -0.04 MPa. Also, remove the pressure switch to see if any powder or oil from the gas has penetrated the sensor.

    (References) The specified pressures are as follows:
    0MPa ~ -0.046MPa (maintenance zone)
    -0.046MPa ~ -0.07MPa (caution zone)
    -0.07MPa ~ 0.096MPa (normal zone)
  2. In certain cases, please remove the switch to have it repaired or replaced.
If problem persists
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