DPD-3 Thermal Conduction Vacuum Dryer  
Issues > Check/Troubleshooting
Secondary Convey Alarm is displayed on the Alarm Screen.
  1. No materials in the drying hopper.
  2. Proximity Switch is defective or its sensitivity is not adjusted properly.
  3. Material is "bridged" in suction hopper for secondary conveying.
  4. The discharge valve is not functioning normally (close).
  5. The delay time for full load in the secondary convey is not set at a sufficient time.
  6. Convey capabilities are in decline.

1. No materials in the drying hopper.
This is a situation when full load (demand signal OFF) is not indicated on the hopper within the specified time.
  1. Check to see if material is in the drying hopper. Also, check to see if the primary hopper is functioning normally.
If the Primary Conveying is abnormal
If problem persists
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2. Proximity Switch is defective or its sensitivity is not adjusted properly.
Proximity Switch is defective or its sensitivity is not adjusted properly.
  1. Check to see if the switch is functioning normally.
  2. Adjust the sensitivity of the switch or replace when necessary.
How to adjust the proximity switch
If problem persists
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3. Material is "bridged" in suction hopper for secondary conveying.
If material in the suction hopper is "bridging", the materials cannot be loaded into the glass tubes and cause a secondary convey alarm.
  1. Check the condition of the suction hopper.
  2. Clear the material bridging. If this happens frequently, conduct a secondary grinding or reduce material loading.
If problem persists
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4. The discharge valve is not functioning normally (close).
  1. Check the condition of the discharge valve. If using while loading granulated materials, see if any particles or spool runners are trapped.

    [Point] Use extra caution not to scratch the seal of the valve.
    [Point] If the spool runner is too long, grind twice.

  2. Clean the valve if any materials are caught. Also, if materials are accumulating in the valve, adjust the secondary convey blow time or the secondary convey air. If the discharge valve (solenoid valve) is damaged, please repair or replace.
If problem persists
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5. The delay time for full load in the secondary convey is not set at a sufficient time.
If the time settings for full load is long and causes too much material to be sent, it may lead to a decline in conveying abilities.
  1. Display the secondary convey settings on the touch panel and check the settings.

    [Point]
    Convey - Set the increasing time from the point where the conveying stops after the material in the receiving hopper exceeds full load (i.e. Demand Signal OFF) on secondary conveying.
    Blow - Set the time for the completion of transfer of the remaining materials in the pipings after loading during timer setting time.

  2. Input the setting time suitable for the quatity of the suction hopper.
If problem persists
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6. Convey capabilities are in decline.
  1. See Material clog occuring in the secondary convey hose (decline of conveying).
If problem persists
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