NEWS

Troubleshooting

  1. Motor malfunction or power shortage：
    • motor shaft stuck
    • incorrect motor wiring
    • incorrect voltage or frequency
  2. Collision between fixed parts and rotating parts：
    • impeller and pump casing
    • impeller and suction ring
    • between wear rings
  3. Control setting：
    • cooling system not opened or malfunction
    • lubrication system not opened or malfunction
    • suction level too low

  1. Motor overload
  2. Collision between fixed parts and rotating parts：
    • impeller and pump casing　
    • impeller and suction ring
    • between wear rings
  3. Control setting：
    • cooling system malfunction
    • lubrication system malfunction
    • bearing temperature too high
    • vibration value too high
    • suction level too low

  1. Pump casing or suction piping not primed with water：
    • pump not prime
    • air bubble inside the suction piping
    • suction piping inlet does not have sufficient water immersion depth
    • suction piping pump liquid leakage
  2. Insufficient NPSHA：
    • suction head too high　
    • saturated steam pressure too high (pump liquid temperature too high)
    • insufficient atmospheric pressure (located at high altitude)
    • suction piping friction loss too high
      • suction diameter too small
      • piping too long
      • too many valves, elbows, or branches
  3. Suction and outlet piping closed：
    • suction piping closed
    • suction valve closed
    • impeller blocked by debris
    • pump blocked by debris
    • outlet piping closed
    • outlet valve closed
  4. Pump rotation speed too slow
  5. Incorrect rotating direction
  6. System total head higher than pump shut-off head

  1. Pump casing or suction piping not primed with water：
    • pump not prime
    • air bubble inside the suction piping
    • suction piping inlet does not have sufficient water immersion depth
    • suction piping pump liquid leakage or air bubble inside
    • too much air in the liquid (>0.5%)
  2. Insufficient NPSHA：
    • suction head too high
    • saturated steam pressure too high (pump liquid temperature too high)
    • insufficient atmospheric pressure (located at high altitude)
    • suction piping friction loss too high
      • suction diameter too small
      • piping too long
      • too many valves, elbows, or branches
  3. Suction and outlet piping blocked:
    • suction piping blocked
    • suction valve blocked
    • pump casing blocked by debris
    • outlet piping blocked
  4. Suction piping under turbulence conditions：
    • the layout distance between suction piping too close
    • suction valve not opened completely
    • elbow layout design error
  5. Too much internal leak：
    • damaged or worn out wear ring and suction ring
    • damaged gasket or O ring
    • too much stuffing box leakage
    • too much flow through bypass piping
  6. Damaged impeller：
    • impeller outside diameter error (outside diameter too small)
    • impeller corroded
    • broken impeller
    • distorted impeller (open type impeller)
  7. Discharge pressure too high：
    • system total head higher than pump's design head
    • outlet valve opening too small
  8. Pump rotating speed too slow
  9. Liquid property is different from the original design (Viscosity too high)
  10. Parallel operating pumps

  1. Air leak in：
    • suction piping inlet does not have sufficient water immersion depth
    • too much air in the liquid (>0.5%)
    • stuffing box has air leak in (washing liquid contains air)
  2. Insufficient NPSHA：
    • suction head too high
    • saturated steam pressure too high (pump liquid temperature too high)
    • insufficient atmospheric pressure (located at high altitude)
    • suction piping friction loss too high
      • suction diameter too small
      • piping too long
      • too many valves, elbows, or branches
  3. Suction piping under turbulence conditions：
    • the layout distance between suction piping too close
    • suction valve not opened completely
    • elbow layout design error
  4. Too much internal leak：
    • damaged or worn out wear ring and suction ring
    • damaged gasket or O ring
    • too much stuffing box leakage
    • too much flow through bypass piping
  5. Damaged impeller：
    • impeller outside diameter error (outside diameter too small)
    • impeller corroded
    • broken impeller
    • distorted impeller (open type impeller)
  6. Outlet pressure too low (Flow rate too high)：
    • system total head higher than pump's design head
    • outlet valve opening too large
  7. Pump rotating speed too slow
  8. Liquid property is different from the original design：
    • viscosity too high
    • specific gravity too low
  9. Parallel operating pumps
  10. Outlet pressure gauge installation error：
    • installed behind the valve　
    • pressure gauge blocked or malfunction

  1. Outlet pressure too low (Flow rate too high)：
    • system total head higher than pump's design head
    • outlet valve opening too small
  2. Liquid property is different from the original design：
    • viscosity too high
    • specific gravity too high
    • concentration too high
    • shown frozen condition
  3. Pump rotating speed too high：
    • frequency too high
    • use incorrect type of motor (Pole number error)
  4. Collision and rubbing between fixed parts and rotating parts：
    • impeller and pump casing
    • impeller and suction ring
    • between wear rings
    • bearing malfunction
  5. Internal leak：
    • damaged or worn out wear ring and suction ring
    • damaged gasket or O ring
    • too much stuffing box leakage
    • too much flow through bypass piping
  6. Impeller：
    • impeller outside dimension too large
    • debris blocked impeller
  7. Shaft：
    • poor shaft centerline alignment
    • main shaft distorted
  8. Gland packing：
    • gland packing cover lock too tight
    • incorrect gland packing installation

  1. Pump casing or suction piping not completely primed with liquid：
    • pump not primed
    • suction piping contains air bubbles
    • suction piping inlet does not have sufficient water immersion depth
    • suction piping liquid leakage
  2. Insufficient NPSHA：
    • suction head too high
    • saturated steam pressure too high (pump liquid temperature too high)
    • insufficient atmospheric pressure (located at high altitude)
    • suction piping friction loss too high
      • suction diameter too small
      • piping too long
      • too many valves, elbows, or branches
  3. Suction and outlet piping block：
    • suction piping block
    • debris blocked impeller
    • debris blocked pump casing
    • outlet piping block
  4. Collision and rubbing between fixed parts and rotating parts：
    • impeller and pump casing
    • impeller and suction ring
    • between wear rings　
    • bearing malfunction
  5. Poor centerline alignment：
    • poor center alignment
    • bent shaft
    • poor rotating body balance
  6. Operating at low flow rate
  7. Unstable foundation
  8. Damaged impeller
  9. Ineffective pump internal mechanics, or liquid balancing devices, lead to excessive thrust

  1. No bearing seal device：
    • gland packing not installed
    • large gap between shaft and casing causing gland packing enters pump casing
  2. Gland packing cover not locked tight
  3. Incorrect gland packing installation
  4. Tilted gland packing cover
  5. Washing liquid pressure too high
  6. Worn out shaft or shaft sleeve
  7. Excessive gland packing worn out：
    • poor centerline alignment
      • poor center alignment
      • bent shaft
      • poor rotating body balance
    • incorrect washing installation：
      • insufficient washing liquid flow into seal ring
      • incorrect lantern ring location, causing washing liquid cannot go in
      • washing liquid has contamination or debris
    • poor rotating body balance
    • damaged shaft or shaft sleeve
    • gland packing cover locked too tight
    • incorrect cooling water route for water jacket cover
  8. Gland packing type is not appropriate for operation：
    • incorrect selection of materials
    • inappropriate gland packing shaft sealing, should change to mechanical seal

  1. Lip end contact not sufficient
  2. Excessive stretches on lip end
  3. Nicking, cutting and stretch marks on the lip part
  4. Shaft surface has scars or too much deviation on machining process
  5. Oil seal has cutting marks
  6. Damaged spring or metal rings
  7. Damaged shaft

  1. Poor centerline alignment：
    • poor center alignment
    • bent shaft
    • poor rotating body balance
  2. Incorrect washing liquid installation：
    • insufficient suction lantern ring washing liquid
    • incorrect lantern ring location causing washing liquid cannot go in
    • washing liquid has contamination or debris
    • excessive high washing liquid pressure
  3. Damaged shaft or shaft sleeve
  4. Large gap between shaft and casing causing gland packing enters pump casing
  5. Gland packing type is not appropriate for operation：
    • incorrect selection of materials
    • inappropriate gland packing shaft sealing, should change to mechanical seal
  6. Incorrect gland packing installation
  7. Excessive tightness on gland packing cover
  8. Incorrect cooling water route for water jacket cover

  1. Improper handling of components：before or during assembly, components are damaged, such as nick, scratch or chip
  2. Incorrect assembly
  3. Improper materials or design：select inappropriate materials for current operating conditions, such as pressure, temperature, rpm or fluid properties
  4. Improper start up or operating procedure：did not feed cooling liquid to the seal causing dry run
  5. Contaminated fluid：hazardous solid particles enter the seal with the fluid
  6. Poor equipment conditions：rotating shaft has large longitudinal swing, deflection or vibration
  7. Worn-out sealing ring：sealing ring may reach it's life cycle

Leak Occurrence location Cause
Sliding area Poor contact area sealing ●incorrect assembled material  shape and dimension ● insufficient buffer with shaft, press too tight ● poor machining on contact surface
Abnormal worn contact area ● caused by dry run ● caused by material erosion ● foreign object enters
Poor installation ● loose and poor tighten ● vibration
Improper selection ● insufficient operating condition
Shaft circumference area Leak out from shaft circumference ● improper material and dimension ● same as above, damaged during installation ● poor machining for shaft surface tolerance
Seal cover circumference area Stuffing box contact surface ● poor machining ● tilted screw lock ● poor sealing gasket
Sealing ring ● poor installation ● seal cover distorted ● contact face overheat caused cracking ● flushing pressure is too high
Indirect causes Vibration and other abnormality ● pump ● shaft ● installation ● temperature condition change during operation

  1. Operating at low flow rate：
    • suction piping liquid leakage
    • system total head higher than pump's design head
    • outlet valve opening too small
    • parallel operating pumps
  2. Collision and rubbing between fixed parts and rotating parts：
    • impeller and pump casing
    • impeller and suction ring
    • between wear rings
  3. Poor centerline alignment：
    • poor alignment
    • bent shaft
    • poor rotating body balance
  4. Bearing damage：
    • insufficient lubrication, bearing resistance too high
    • incorrect low friction bearing installation
    • lubricant has contamination or poor quality
    • water inside the bearing caused rusting of bearings
    • water cool-type bearings, due to over-cooling, moisture in air condensed inside the bearing compartment.

  1. Operating at low flow rate：
    • suction piping liquid leakage
    • system total head higher than pump's design head
    • discharge valve opening too small
    • parallel operating pumps
  2. Poor centerline alignment：
    • poor alignment
    • bent shaft
    • poor rotating body balance
  3. Collision and rubbing between fixed parts and rotating parts：
    • impeller and pump casing
    • impeller and suction ring
    • between wear rings
    • bearing malfunction
  4. Pump not primed or dry operation
  • Headquarters Address：3 Cheng Kung 3rd St. Minshiung Industrial Park Chiayi County, Taiwan
  • Tel：886-5-2133888
  • Fax：886-5-2131888
  • E-mail : stpsales@santaipumps.com.tw
  • Copyrights © SAN TAI 2024 All Rights Reserved.