Raypak RAYTHERM 133-4001 - Manual (Page 37)

37
Pumps
Failure To Pump
1. Pump not properly primed.
2. Wrong direction of rotation.
3. Speed too low.
4. Total head too high.
Reduced Capacity And/Or Head
1. Air pockets or leaks in suction line.
2. Clogged impeller.
3. Foot valve strainer too small or clogged.
4. Excessive suction lift (over 15 ft.).
5. Insufficient positive suction head (for hot water).
6. Total head more than that for which pump is
intended.
7. Excessively worn impeller and wearing rings.
Rapid Wear Of Coupling
1. Misalignment or a bent shaft.
2. Sagging motor mounts (over-oiling).
Pump Loses Prime
1. Air leaks in suction line.
2. Excessive amount of air in water.
3. Water seal in stuffing box not functioning.
4. Excessive suction lift and pump operating too
near shut-off point.
Overloaded Driving Unit
1. Head much lower than that for which pump is
designed.
2. Speed too high or higher than that contemplated.
Mechanical Troubles and Noise
1. Misalignment.
2. Excessive suction lift or vapor binding (hot
water).
3. Bent shaft and/or damaged bearings.
4. Suction and discharge piping not properly sup-
ported and anchored.
Fig. 49: Tube Cleaning Procedure