Flowserve Twin Screw Rotary - Manual (Page 48)

TWIN SCREW PUMPS. ORIGINAL USER INSTRUCTIONS. ENGLISH. 71569243 – 07/10
Page 45 of 53
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FAULT SYMPTOM
P u m p o v e r h e a t s a n d s e i z e s
⇓ ⇓ B e a r i n g s h a v e s h o r t l i f e
⇓ ⇓ P u m p v i b r a t e s o r i s n o i s y
⇓ ⇓ M e c h a n i c a l s e a l h a s s h o r t l i f e
⇓ ⇓ M e c h a n i c a l s e a l l e a k s e x c e s s i v e l y
⇓ ⇓ P u m p r e q u i r e s e x c e s s i v e p o w e r
⇓ ⇓ P u m p l o s e s p r i m e a f t e r s t a r t i n g
⇓ ⇓ I n s u f f i c i e n t p r e s s u r e d e v e l o p e d
⇓ ⇓ I n s u f f i c i e n t c a p a c i t y d e l i v e r e d
⇓ ⇓ P u m p d o e s n o t d e l i v e r l i q u i d
⇓ ⇓
PROBABLE CAUSES POSSIBLE REMEDIES
z z z z z Bearings worn Replace bearings.
z z z Wearing surfaces worn. Replace screw tip and body bore coatings
z z z
Screws damaged or eroded. Replace or CONSULT FLOWSERVE for improved
material selection.
z Leakage under sleeve due to joint failure. Replace joint and check for damage.
z z Shaft sleeve worn or scored or running off centre. Check and renew defective parts.
z z z
Mechanical seal improperly installed. Check alignment of faces or damaged parts and
assembly method used.
z z z
Incorrect type of mechanical seal for operating
conditions. CONSULT FLOWSERVE.
z z z z z Shaft(s) running off centre because of worn
bearings or misalignment. Check misalignment and correct if necessary. If
alignment satisfactory check bearings for excessive
wear.
z z z z z Shafts out of balance resulting in vibration.
z z z Abrasive solids in liquid pumped.
z z
Internal misalignment of parts preventing seal ring
and seat from mating properly.
Check and CONSULT FLOWSERVE.
z z
Mechanical seal was run dry. Check mechanical seal condition and source of dry
running and repair.
z z
Internal misalignment due to improper repairs Check method of assembly, possible damage or
state of cleanliness during assembly.
Remedy or CONSULT FLOWSERVE, if necessary.
z z z Worn bearings or timing gears Check condition of bearings and gears. Check oil
levels and condition of lubricant
z z z Excessive lubricant in housings (external pump) Check oil levels.
z z z Lack of lubrication for bearings. Check hours run since last change of lubricant, the
schedule and its basis.
z z z
Improper installation of bearings (damage during
assembly, incorrect assembly, wrong type of
bearing etc). Check method of assembly, possible damage or
state of cleanliness during assembly and type of
bearing used. Remedy or CONSULT
FLOWSERVE, if necessary.
z z z Damaged bearings due to contamination. Check contamination source and replace damaged
bearings.
C. MOTOR ELECTRICAL PROBLEMS
z z z z Wrong direction of rotation. Reverse 2 phases at motor terminal box.
z z Motor running on 2 phases only. Check supply and fuses.
z z z Motor running too slow. Check motor terminal box connections and voltage.