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Lowara 10SV 05F022 1015L1191 — понимание кавитации и её влияние на насосные системы [64/72]
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64
The minimum operating values that can be reached at the
pump suction end are limited by the onset of cavitation.
Cavitation is the formation of vapour-filled cavities within
liquids where the pressure is locally reduced to a critical value,
or where the local pressure is equal to, or just below the
vapour pressure of the liquid.
The vapour-filled cavities flow with the current and
when they reach a higher pressure area the vapour
contained in the cavities condenses. The cavities collide,
generating pressure waves that are transmitted to the
walls. These, being subjected to stress cycles, gradually
become deformed and yield due to fatigue. This
phenomenon, characterized by a metallic noise
produced by the hammering on the pipe walls, is called
incipient cavitation.
The damage caused by cavitation may be magnified by
electrochemical corrosion and a local rise in
temperature due to the plastic deformation of the
walls. The materials that offer the highest resistance to
heat and corrosion are alloy steels, especially austenitic
steel. The conditions that trigger cavitation may be
assessed by calculating the total net suction head,
referred to in technical literature with the acronym
NPSH (Net Positive Suction Head).
The NPSH represents the total energy (expressed in m.)
of the liquid measured at suction under conditions of
incipient cavitation, excluding the vapour pressure
(expressed in m.) that the liquid has at the pump inlet.
To find the static height hz at which to install the
machine under safe conditions, the following formula
must be verified:
hp + hz ≥ (NPSHr + 0.5) + hf + hpv
where:
hp is the absolute pressure applied to the free liquid
surface in the suction tank, expressed in m. of
liquid; hp is the quotient between the barometric
pressure and the specific weight of the liquid.
hz is the suction lift between the pump axis and the
free liquid surface in the suction tank, expressed
in m.; hz is negative when the liquid level is
lower than the pump axis.
hf is the flow resistance in the suction line and its
accessories, such as: fittings, foot valve, gate
valve, elbows, etc.
hpv is the vapour pressure of the liquid at the
operating temperature, expressed in m. of
liquid. hpv is the quotient between the Pv vapour
pressure and the liquid’s specific weight.
0,5 is the safety factor.
The maximum possible suction head for installation
depends on the value of the atmospheric pressure
(i.e. the elevation above sea level at which the pump
is installed) and the temperature of the liquid.
To help the user, with reference to water temperature
(4° C) and to the elevation above sea level, the
following tables show the drop in hydraulic pressure
head in relation to the elevation above sea level, and
the suction loss in relation to temperature.
Friction loss is shown in the tables at pages 66-67 of
this catalogue. To reduce it to a minimum, especially
in cases of high suction head (over 4-5 m.) or within
the operating limits with high flow rates, we
recommend using a suction line having a larger
diameter than that of the pump’s suction port.
It is always a good idea to position the pump as close
as possible to the liquid to be pumped.
Make the following calculation:
Liquid: water at ~15°C γ = 1 kg/dm
3
Flow rate required: 25 m
3
/h
Head for required delivery: 70 m.
Suction lift: 3,5 m.
The selection is an 33SV3G075T pump whose NPSH
required value is, at 25 m
3
/h, of 2 m.
For water at 15 °C
hp = Pa / γ = 10,33m, hpv = Pv / γ = 0,174m (0,01701 bar)
The Hf flow resistance in the suction line with foot
valves is ~ 1,2 m.
By substituting the parameters in formula with the
numeric values above, we have:
10,33 + (-3,5) ≥ (2 + 0,5) + 1,2 + 0,17
from which we have: 6,8 > 3,9
The relation is therefore verified.
Water
temperature (°C) 20 40 60 80 90 110 120
Suction
loss (m) 0,2 0,7 2,0 5,0 7,4 15,4 21,5
Elevation above
sea level (m) 500 1000 1500 2000 2500 3000
Suction
loss (m) 0,55 1,1 1,65 2,2 2,75 3,3
NPSH
1
1
TECHNICAL APPENDIX
Содержание
- Enntech p.1
- Lowara e sv hydrovar xylect are trademarks of xylem inc or one of its subsidiaries all other trademarks of registered trademarks are property of their respective owners p.2
- E sv series hydraulic performance range at 50 hz p.2
- Contents p.3
- Water treatment plants p.5
- Wash systems p.5
- Vertical multistage electric pumps p.5
- Specifications pump p.5
- Pressure boosting and water supply systems p.5
- Pharmaceutical food beverage industries p.5
- Irrigation systems p.5
- I alert p.5
- Handling of water free of suspended solids in the civil industrial and agricultural sectors p.5
- Handling of moderately aggressive liquids demineralised water water and glycol etc p.5
- E sv series p.5
- Circulation of hot and cold water for heating cooling and conditioning systems p.5
- Boiler feed p.5
- Arket sectors p.5
- Applications p.5
- Available on request p.6
- Characteristics of 33 46 66 92 125sv series p.6
- Characteristics of 1 3 5 10 15 22sv series p.6
- Version diagram p.7
- Versioni 33 46 66 92 125sv p.7
- Versioni 1 22sv p.7
- General characteristics 2 pole sv p.7
- Caratteristiche generali 1 3 5 10 15 22 33 46 66 92 125 sv 2 poli 50 hz p.7
- Available for p versions see specific catalogue p.7
- 46 66 92 125sv versions p.7
- 3 5 10 15 22sv versions p.7
- H number of impellers 10 f version aisi 304 round flanges rated motor power 11 kw 50 hz frequency three phase p.8
- F 10 sv p.8
- Example 22sv10f110t sv series electric pump flow rate 22 p.8
- Example 125sv8 2ag550t sv series electric pump flow rate 125 p.8
- 46 66 92 125sv series p.8
- 3 5 10 15 22sv series p.8
- L 550 t p.8
- L 110 t p.8
- Identification code p.8
- H number of impellers 8 2 of which with a smaller external diameter type a g version aisi 304 cast iron round flanges rated motor power 55 kw 50 hz frequency three phase p.8
- Rating plate p.9
- Legend p.9
- 22sv pump 33 125sv pump p.9
- 22sv electric pump 33 125sv electric pump p.9
- N v c k versions p.10
- Materiali 1 22sv versioni n v c k p.10
- Materiali 1 22 sv versioni f t r p.10
- Kw electric pump cross section and main components p.10
- F t r versions p.10
- 3 5sv series and 10 15 22sv series p.10
- 5 kw electric pump cross section and main components p.11
- 15 22sv series p.11
- N v c k versions p.11
- Materiali 10 22sv versioni n v c k p.11
- Materiali 10 22 sv versioni f t r p.11
- F t r versions p.11
- N versions p.12
- Materiali 33 92sv versioni n p.12
- Materiali 33 92sv versioni g p.12
- G versions p.12
- 46 66 92sv series electric pump cross section and main components p.12
- Sv series electric pump cross section and main components p.13
- N versions p.13
- Materiali 125sv versioni n p.13
- Materiali 125 sv versioni g p.13
- G versions p.13
- E sv series mechanical seals according to en 12756 p.14
- 15 22sv 4 kw 10 15 22sv 5 5 kw 33 46 66 92 125sv p.14
- Type of seal p.14
- Pressure temperature application limits for complete pump applicable with any of the seals listed above p.14
- List of materials p.14
- Tabella di compatibilita dei materiali a contatto con i principali liquidi p.15
- Compatibility chart for materials in contact with most commonly used liquids p.15
- Single phase motors at 50 hz 2 pole p.16
- Motori monofase per serie 1 22 sv 50 hz 2 poli p.16
- Erp 2009 125 ec p.16
- E sv series motors p.16
- Motori trifase per serie 1 125 sv 50 hz 2 poli fino a 22 kw motori trifase per serie 1 125 sv 50 hz 2 poli fino a 22 kw motori trifase per serie 1 125 sv 50 hz 2 poli fino a 22 kw motori trifase per serie 1 125 sv 50 hz 2 poli fino a 22 kw p.17
- E sv series three phase motors at 50 hz 2 pole up to 22 kw p.17
- Rumorosita motori sv 2 poli 50hz p.18
- Motori trifase per serie 1 125 sv 50 hz 2 poli da 30kw fino a 55kw motori trifase per serie 1 125 sv 50 hz 2 poli da 30kw fino a 55kw motori trifase per serie 1 125 sv 50 hz 2 poli da 30kw fino a 55kw motori trifase per serie 1 125 sv 50 hz 2 poli da 30kw fino a 55kw p.18
- Motor noise 2 pole motors p.18
- E sv series three phase motors at 50 hz 2 pole from 30 to 55 kw p.18
- Available voltages sm and plm motors for e sv series 2 pole p.19
- W22 motors for e sv series 2 pole p.19
- Surface motors standard voltages offering motori di superficie specchietto tensioni disponibile p.19
- Surface motors standard tensions offering p.19
- Erp 2009 125 ec p.20
- E sv series pumps p.20
- Special features benefits p.21
- Special configurations p.21
- Identification code p.21
- E sv series version with hydrova p.21
- Benefits of e svh with hydrova p.21
- Background and context p.21
- Typical example of energy savings p.22
- Operating principle p.22
- Lowara p.22
- E sv series version with hydrova p.22
- Heating ventilation and air conditioning hvac p.23
- Water treatment p.23
- Water supply and pressure boosting p.23
- Typical applications of e sv series electric pumps p.23
- Pharmaceutical and food beverage industries p.23
- Light industry p.23
- Irrigation and agriculture p.23
- Iso 9906 2012 grade 3b p.24
- E sv series hydraulic performance range at 50 hz 2 poles p.24
- 2900 rpm e sv p.24
- Tabella di prestazioni idrauliche serie 1sv 3sv 5sv 2p 50 hz p.25
- 3 5sv series hydraulic performance table at 50 hz 2 poles p.25
- Tabella di prestazioni idrauliche serie 10sv 15sv 22sv 2p 50 hz p.26
- 15 22sv series hydraulic performance table at 50 hz 2 poles p.26
- Tabella di prestazioni idrauliche serie sv33 46 2 poli 50 hz p.27
- 46sv series hydraulic performance table at 50 hz 2 poles p.27
- 92sv series hydraulic performance table at 50 hz 2 poles p.28
- Tabella di prestazioni idrauliche serie 66 92sv 2 poli 50 hz p.28
- Tabella di prestazioni idrauliche serie 125sv 2p 50 hz p.29
- Sv series hydraulic performance table at 50 hz 2 poles p.29
- Sv series 2 to 15 stages dimensions and weights at 50 hz 2 poles p.30
- Dimensioni e pesi serie 1sv 2 poli 50 hz p.30
- Sv series 2 to 15 stages operating characteristics at 50 hz 2 poles p.31
- Iso 9906 2012 grade 3b p.31
- 2900 rpm p.31
- Sv series 17 to 37 stages dimensions and weights at 50 hz 2 poles p.32
- Dimensioni e pesi serie 1sv 2 poli 50 hz p.32
- Sv series 17 to 37 stages operating characteristics at 50 hz 2 poles p.33
- Iso 9906 2012 grade 3b p.33
- 2900 rpm p.33
- Sv series dimensions and weights at 50 hz 2 poles p.34
- Dimensioni e pesi serie 3sv 2 poli 50 hz p.34
- 2900 rpm p.35
- Sv series operating characteristics at 50 hz 2 poles p.35
- Iso 9906 2012 grade 3b p.35
- Sv series dimensions and weights at 50 hz 2 poles p.36
- Dimensioni e pesi serie 5sv 2 poli 50 hz p.36
- Sv series operating characteristics at 50 hz 2 poles p.37
- Iso 9906 2012 grade 3b p.37
- 2900 rpm p.37
- Sv series dimensions and weights at 50 hz 2 poles p.38
- Dimensioni e pesi serie 10sv 2 poli 50 hz p.38
- Sv series operating characteristics at 50 hz 2 poles p.39
- Iso 9906 2012 grade 3b p.39
- 2900 rpm p.39
- Sv series dimensions and weights at 50 hz 2 poles p.40
- Dimensioni e pesi serie 15sv 2 poli 50 hz p.40
- Iso 9906 2012 grade 3b p.41
- 2900 rpm p.41
- Sv series operating characteristics at 50 hz 2 poles p.41
- Sv series dimensions and weights at 50 hz 2 poles p.42
- Dimensioni e pesi serie 22sv 2 poli 50 hz p.42
- Sv series operating characteristics at 50 hz 2 poles p.43
- Iso 9906 2012 grade 3b p.43
- 2900 rpm p.43
- Sv series dimensions and weights at 50 hz 2 poles p.44
- Dimensioni e pesi serie 33sv 2 poli 50 hz p.44
- Sv series operating characteristics at 50 hz 2 poles p.45
- Iso 9906 2012 grade 3b 2900 rpm p.45
- Iso 9906 2012 grade 3b p.45
- 2900 rpm p.45
- Sv series dimensions and weights at 50 hz 2 poles p.46
- Dimensioni e pesi serie 46sv 2 poli 50 hz p.46
- Iso 9906 2012 grade 3b p.47
- 2900 rpm p.47
- Sv series operating characteristics at 50 hz 2 poles p.47
- Iso 9906 2012 grade 3b 2900 rpm p.47
- Sv series dimensions and weights at 50 hz 2 poles p.48
- Dimensioni e pesi serie 66sv 2 poli 50 hz p.48
- Sv series operating characteristics at 50 hz 2 poles p.49
- Iso 9906 2012 grade 3b p.49
- 2900 rpm p.49
- Sv series dimensions and weights at 50 hz 2 poles p.50
- Dimensioni e pesi serie 92sv 2 poli 50 hz p.50
- Sv series operating characteristics at 50 hz 2 poles p.51
- Iso 9906 2012 grade 3b p.51
- 2900 rpm p.51
- Sv series dimensions and weights at 50 hz 2 poles p.52
- Dimensioni e pesi serie 125sv 2 poli 50 hz p.52
- Iso 9906 2012 grade 3b p.53
- 2900 rpm p.53
- Sv series operating characteristics at 50 hz 2 poles p.53
- Sensors p.55
- Accessories p.55
- Specifications p.56
- Sensor for detecting the presence of water based on the optoelectronic principle therefore non invasive and with no moving parts the sensor features an electronic contact on off which stops the pump if there is no water in the seal area the sensor opens the electric contact if there is no water after they factory set delay 10 seconds elapses the sensor is supplied as a kit complete with 2 metres of cable an epdm o ring gasket and a stainless steel adapter p.56
- Revisione a p.56
- Protection sensor against dry running p.56
- Operating principle p.56
- Note deriva dasol_m0004_a_sc p.56
- Modello sensore ottico di livello p.56
- General operating features p.56
- Disegnatore m caldarde p.56
- Data 26 novembre 2012 p.56
- Codice sol_m0005_a_sc p.56
- Available in two power versions depending on foreseen use p.56
- Pumps for the 33 46 66 92 125sv series the 3 8 x 1 2 adaptor ring included in the kit must also be mounted p.57
- Wiring diagram p.57
- The sensor can be directly mounted on the filling plug of the e s p.57
- Sensor kit drp hv sensor kit drp hv code 109394600 p.57
- Sensor kit drp gp sensor kit drp gp code 109394610 p.57
- Vibration monitor p.58
- Specifications p.58
- Serie e s p.58
- I aler p.58
- Vibration monitoring p.59
- Serie e s p.59
- I aler p.59
- Dimensions of oval counterflanges sv t p.60
- Dimensioni controflange ovali per 1 2 p.60
- Counterflange p.60
- According to en 1092 1 p.60
- 3sv 25 rp 1 85 10 115 16 14 4 25 5sv 32 rp 1¼ 100 13 140 16 18 4 25 10sv 40 rp 1½ 110 14 150 19 18 4 25 15 22sv 50 rp 2 125 16 165 24 18 4 25 33sv 65 rp 2½ 145 16 185 23 18 4 16 46sv 80 rp 3 160 17 200 27 18 8 16 66sv 92sv 100 rp 4 180 18 220 31 18 8 16 p.60
- Sv g n according to en 1092 1 p.60
- Dimensions of weld on round p.60
- Dimensions of round threaded counterflanges sv f n r g p.60
- Dimensions of victauli p.61
- Dimensions of clamp couplings sv c p.61
- Dimensioni giunti victaulic sv2 p.61
- Dimensioni giunti clamp 1 22 sv p.61
- Couplings sv v p.61
- Special versions on request p.62
- Technical appendix p.64
- Vapour pressure vapour pressure ps and ρ density of water table p.65
- Tensione di vapore tabella tensione di vapore ps e densita ρ dell acqua p.65
- Technical appendix p.65
- Technical appendix p.66
- Table of flow resistance in 100 m of straight cast iron pipeline hazen williams formula c 100 p.66
- Tabella perdite di carico per 100 m tubazione diritta in ghisa formula hazen williams c 100 p.66
- The table is valid for the hazen williams coefficient c 100 cast iron pipework for steel pipework multiply the values by 1 41 for stainless steel copper and coated cast iron pipework multiply the values by 1 85 when the equivalent pipeline length has been determined the flow resistance is obtained from the table of flow resistance the values given are guideline values which are bound to vary slightly according to the model especially for gate valves and non return valves for which it is a good idea to check the values supplied by manufacturers p.67
- The flow resistance is calculated using the equivalent pipeline length method according to the table below p.67
- Technical appendix p.67
- Tabella lunghezza di tubazione equivalente p.67
- Flow resistance table of flow resistance in bends valves and gates p.67
- Volumetric capacity p.68
- Volume p.68
- Temperature p.68
- Technical appendix p.68
- Pressure and head p.68
- Length p.68
- Technical appendix p.69
- Further product selection and documentation xylec p.69
- Technical appendix p.70
- Further product selection and documentation xylec p.70
- Enntech p.72
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