AU0340 Pump Troubleshooting Pocket Assistant_Replacement Front Cover_LORES.pdf
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Transcript of AU0340 Pump Troubleshooting Pocket Assistant_Replacement Front Cover_LORES.pdf
7/27/2019 AU0340 Pump Troubleshooting Pocket Assistant_Replacement Front Cover_LORES.pdf
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Pump Troubleshooting Pocket Assistant
™
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Table of Contents Table of Contents
Pump Troubleshooting Symptoms
Hopper Overflows 1
Overheating or seizure of pump 2
Short bearing life 3
Vibration & noise from pump 4Packing has short life 5
Leakage from stuffing box 6
Excessive motor power required 7
Pump loses prime 8
Insufficient pressure 9
Reduced discharge delivery 10
Failure to discharge 12
Pump Troubleshooting for Glands
Problem | Cause | Solution 13
Basic Pumping Formulae
Calculating quantity to be pumped from weight of solids 16
Calculating slurry sg (sm) 17
Calculating slurry Cv (solids concentration by volume) 17
Durand’s settling velocity chart 18
Calculating average velocity through a circular pipe 19
Calculating limited settling velocity 19
Calculating static head 20
Copyright © 2011, Weir Minerals Australia Ltd. All rights reserved.
CAVEX, WARMAN, HAZLETON and MULTIFLO are registered trademarks of Weir Minerals Australia Ltd; LEWIS PUMPS is a registered trademark of Envirotech PumpsystemsInc; GEHO is a registered trademarks of Weir Minerals Netherlands bv; FLOWAY is a registered trademark of Weir Floway Inc.; VULCO is a registered trademark of Vulco S.A.;
ISOGATE is a registered trademark of Weir do Brasil Ltda; LINATEX is a registered trademark of Linatex Limited (UK).”
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1
Pump Troubleshooting
2
Pump Troubleshooting
SYMPTOMS - Hopper Overows
Pump not primed
Excessive amount of air or gas in liquid
Inlet of suction pipe insufficiently submerged
Blocked suction line
Suction valve closed
Inlet pipe diameter too small or length of inlet pipe
too long
Speed too slow or wrong direction of rotation
Coupling or drive belts not transmitting power
Total head of system higher than design
Specific gravity of liquid different from design
Entrained air in pump, pump hopper requires baffles
Badly installed pipe line or gaskets partly blocking pipe
Foreign matter in impeller
SYMPTOMS - Overheating or seizure o pump
Pump not primed
Insufficient margin between suction pressure and
vapour pressure
Operation at very low capacity
Drive misalignment
Lack of lubrication
Improper installation of bearings
Rotating part rubbing on stationary part
Impeller out of balance, resulting in vibration
Excessive thrust caused by a mechanical failure inside the
pump
Excessive amount of lubricant in bearing housing causing
high bearing temp
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3
Pump Troubleshooting
4
Pump Troubleshooting
SYMPTOMS - Short bearing lie
Drive misalignment
Shaft bent
Rotating part rubbing on stationary part
Bearings worn
Impeller out of balance, resulting in vibration
Shaft running off-centre because of worn bearings or misalignment
Lack of lubrication
Excessive amount of lubricant in bearing housing causing high bearing temp
Improper installation of bearings
Dirt getting into bearings
Rusting of bearings due to water getting into housing
SYMPTOMS - Vibration & Noise from Pump
Pump or suction pipe not completely filled with liquid
Suction lift too high
Insufficient margin between suction pressure and vapour pressure
Foot valve too small
Foot valve partially clogged
Inlet of suction pipe insufficiently submerged
Operation at very low capacity
Badly installed pipe line or gaskets partly blocking pipe
Drive misalignment
Rotating part rubbing on stationary part
Shaft running off-centre because of worn bearings or misalignment
Foreign matter in impeller
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5
Pump Troubleshooting
6
Pump Troubleshooting
SYMPTOMS - Packing has short life
Misalignment
Shaft bent
Shaft or shaft sleeves worn or scored at the packing
Packing improperly installed
Shaft running off-centre because of worn bearings or misalignment
Gland sealing water flow inadequate due to worn shaft seal components
Gland sealing water pressure inadequate
Dirt or grit in sealing liquid, leading to scoring shaft sleeve
Expeller worn or blocked
Excessive clearance at bottom of stuffing box, forcing packing into pump
SYMPTOMS - Leakage from stuffing box
Misalignment
Shaft bent
Shaft or shaft sleeves worn or scored at the packing
Packing wrong size
Packing improperly installed
Incorrect type of packing for operating conditions
Shaft running off-centre because of worn bearings or misalignment
Gland sealing water pressure too high causing packing extrusion
Dirt or grit in sealing liquid, leading to scoring shaft sleeve
Expeller worn or blocked
Excessive clearance at bottom of stuffing box, forcing packing into pump
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7
Pump Troubleshooting
8
Pump Troubleshooting
SYMPTOMS - Excessive motor power required
Speed too high
Wrong direction of rotation
Total head of system higher than design
Total head of system lower than design
Specific gravity of liquid different from design
Viscosity of liquid differs from that for which designed
Misalignment
Shaft bent
Rotating part rubbing on stationary part
Packing improperly installed
Gland too tight, resulting in no flow of liquid to lubri cate packing
SYMPTOMS - Pump loses prime
Pump or suction pipe not completely filled with liquid
Suction lift too high
Excessive amount of air or gas in liquid
Air pocket in suction line
Air leaks into suction line
Air leaks into pump through stuffing box
Inlet of suction pipe insufficiently submerged
Blocked suction line
Foreign matter in impeller
Inlet pipe diameter too small or length of inlet pipe too long
Entrained air in pump. Pump hopper requires baffles
Badly installed pipe line or gaskets partly blocking pipe
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9
Pump Troubleshooting
10
Pump Troubleshooting
SYMPTOMS - Insufficient pressure
Excessive amount of air or gas in liquid
Speed too slow
Total head of system higher than design
Viscosity of liquid differs from that for which designed
Entrained air in pump. Pump hopper requires baffles
Badly installed pipe line or gaskets partly blocking pipe
Impeller damaged or worn
Casing gasket defective, permitting internal l eakage
Foreign matter in impeller
SYMPTOMS - Reduced discharge delivery
Pump or suction pipe not completely filled with liquid
Suction lift too high
Insufficient margin between suction pressure and vapour
pressure
Excessive amount of air or gas in liquid
Air pocket in suction line
Air leaks into suction line
Air leaks into pump through stuffing box
Foot valve too small
Foot valve partially clogged
Inlet of suction pipe insufficiently submerged
Blocked suction line
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11
Pump Troubleshooting
12
Pump Troubleshooting
SYMPTOMS - Reduced discharge delivery (cont)
Inlet pipe diameter too small or length of inlet pipe too long
Speed too slow - slippage of vee belts
Speed too slow – incorrect size pulleys
Speed too slow – incorrect “pole” of electric motor
Speed too high
Wrong direction of rotation
Total head of system higher than design
Viscosity of liquid differs from that for which designed
Entrained air in pump. Pump hopper requires baffles
Badly installed pipe line or gaskets partly blocking pipe
Foreign matter in impeller
SYMPTOMS - Failure to discharge
Pump not primed
Pump or suction pipe not completely filled with liquid
Suction lift too high
Insufficient margin between suction pressure and vapour pressure
Air pocket in suction line
Inlet of suction pipe insufficiently submerged
Blocked suction line
Inlet pipe diameter too small or length of inlet pipe too long
Speed too slow
Total head of system higher than design
Impeller damaged or worn
Foreign matter in impeller
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13
Pump Troubleshooting - Glands
14
Pump Troubleshooting - Glands
Problem Cause Solution•Short packing lie
•Short sleeve lie
•Slurry exits gland
•Slurry wears packing
•Slurry wears shat sleeve
•Packing over heating and burning
due to low GSW pressure
• Increase gland sealing water (GSW) pressure
• Increase GSW owrate
•Loosen gland to increase ow
•Stop, cool down, repack and then restart with
correct GSW pressure and ow
•Flow rom gland too
low, in worst case
steam exits rom gland
•Pressure too high causing packing
extrusion and ow restriction
•Gland too tight
•Packing too sot or high pressure
•Stop, cool down, repack and then restart with
correct, GSW pressure and ow
•Loosen gland
•Review packing type
•Use packing retainer ring
•Reduce GSW pressure
•GSW ows around
outside o packing rings
•Packing rings wrong size or ft-up
wrong
•Repack gland with correct packing
•Review order o assembly
•Too much ow rom
gland
•Shat sleeve worn
• Wrong size o packing
• Worn packing
•Disassemble and reurbish gland with new parts
Caution1. On no account should the gland be loosened to such an extent that it disengages from the stuffing box.
2. Putting more things into a stuffi ng box when problems occur will only be a short-term fix. Extra packing will exacerbate any general wear and
eventually lead to excessive leakage.
3. Corrosion by saline GSW may be minimised by the use of appropriate alloys. The leakage of saline GSW from the gland must be trapped and
conveyed to waste to avoid corrosion of the pump base and other components.
Steps for the correct fitting of packings into the stuffing box.
1. Packing is normally available in pre-cut and formed rings, or alternatively the user can cut rings from a roll.
2. It is critical that each packing ring is cut to the correct length.
3. The packing cut should be at an angle of 450, ie, a scarf joint.
4. The packing should fill the annulus. A length of key steel or similar should be used to push the packing into
the stuffing box. Care should be taken to start fitting the packing on the joint side and then work around the
ring to the opposite side. This should prevent stretching the ring, which could lead to overlap at the cut.
5. The packing should push in easily. If not, check the section dimensions. If incorrect the packing should be
replaced. Do not roll formed rings.
6. Each packing should be tamped into position before fitting the next packing. Optimum arrangements for multiple rings of packing are shown below.
7. When all packing rings have now been fitted, assemble the gland and nip the bolts to flatten packing rings
evenly. Do not tighten fully.
8. Run the pump. If excessive leakage occurs, tighten the bolts slightly and leave for at least an hour. Repeat
if excessive leakage continues. Note that a good steady even drip or constant stream is desirable to cool and
lubricate the gland.
PACKING CUT
DETAIL
450
GLAND
PACKING
4 RING ARRANGEMENT 3 RING ARRANGEMENT
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15
Basic Pumping Formulae
16
Basic Pumping Formulae
Calculating quantity to be pumped from weight of solids
Weight o solids in slurry = 65 tonnes (at SG = 2.65/hr)
Weight o volume o water = 65 = 24.5tequal to solids volume 2.65
Weight o water in slurry = 70% x 65t = 151.7t
o 30% Cw 30%
Total weight o equal volume = 24.5 + 151.7 = 176.2t/hr o water to slurry
Given 1 tonne o water = 1m3
then slurry ow = 176.2m3/hr = 49 litres/second
Example: Sand slurry
65 tonnes per hour of sand
Solids SG = 2.65
Particle d50 = 211mm
Cw of solids = 30%
Zd static discharge head = 20m
zS
Dz
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17
Basic Pumping Formulae
18
Basic Pumping Formulae
Calculating slurry sg (sm)
Total weight o slurry = 65t solids + 151.7t water = 216.7t/hr (from previous calculation)
Total weight o equal volume = 24.5 + 151.7 = 176.2 t/hr o water to slurry
Sm = actual weight of slurry
weight o equal volume o water = 216.7tph176.2tph
= 1.23
Calculating slurry Cv (solids concentration by volume)
For Cv apply a simple ormula:Cv = [(Sm - Sl) / (S-Sl)] x 100
= [(1.23 - 1) / (2.65 - 1)] x 100= [0.23 / 1.65] x 100
Cv = 13.9% (solids concentration by volume)
Durand’s SettlingVelocity Chart
Where:
Sm = SG mixture
SI = SG liquid
S = SG solidsd
50= AVERAGE PARTICLE SIZE μm
EXAMPLE:
VALUES OF FL
FOR
D50
= 0.6mm
Cv
= 5% TO 40%
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19
Basic Pumping Formulae
20
Basic Pumping Formulae
Calculating static head
Static head is the dierence in vertical heighto the inlet liquid level and the dischargeliquid level at the air interace.
It is given by the formula:Z = Zd - Zs
Where: Zd and Zs are the static discharge head from pump centreline to discharge liquid level and static inlet (suction) head from pumpcentreline to inlet liquid level respectively. Suction Lift applications have negative valuesfor Zs.
In this instance, by substitution:Z = 20 - 1
= 19 m
Calculating average velocity through a circular pipe
V = (Q X 1273) / d2
= (49 x 1273) / 1502
V = 2.8 m/s
Calculating limiting settling velocity
VL = FL 2gD (S -Sl)Sl
= 1.04 x [2 x 9.81 x 0.15 ((2.65-1)/1]
VL = 2.3 m/s
Therefore, the 150mm pipe is suitable as:
V > VL (ie 2.8 m/s actual velocity > 2.3 m/s settling)
Where:
V = flow velocity m/s
Q = flow rate in l/s
d = pipe diameter in millimetres
Durand’s Formula:
VL = FL 2gD (S -Sl)Sl
Where:
VL = critical velocity m/s
FL = Durand’s Settling Factor (from chart)
g = gravitational constant
D = pipe inside diameter m
S = SG solids
Sl = SG liquid
zS
Dz
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Weir Minerals Australia Ltd
Tel: +61 2 9934 5100
Fax: +61 2 9934 5201
www.weirminerals.com
1 Marden Street
Artarmon NSW 2064
Australia
ExcellentMineralsSolutions
AU0340 01.03.11