catalog pentax

8/12/2019 Catalog Pentax

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CNG TY TNHH T-M324A/10 Phan nhPhng, P.1, Q.PN, TP.HCMWeb: www.tm-pccc.com - Mail: [email protected]: 3.845.2126 Fax: 3.995.3027

I. The pump > Introduction

When a fluid, be it hot or cold, has to be "moved" in a system, pumps are used. In other words, and in atechnically more appropriate manner, the pump is a hydraulic working machine which has the function ofincreasing the total (mechanical) energy of a liquid; this means that the pump transfers to the fluid, which flowsthrough it, to the extent allowed by its performance, part of the energy that it receives from the driving motor.At this point we can already make an important distinction based on the driving motor:- we speak of an electropump when the mechanical energy necessary for the pump to turn is provided by an

electric motor;- we speak of a motor pump when this mechanical energy is provided by a heat engine (combustion engine, dieselengine, etc.).

Here we shall deal exclusively with electropumps - and further on we shall pause to describe the most importantcharacteristics of the electric motors that drive them - because:

1) Electric motors are the most widely used;2) PENTAX produces and markets electropumps.

Considering the definition, we may proceed with our description of the pump, starting with the fundamental

factors that describe its operation: flow rate;1. head;2. power;3. efficiency;4. speed;5. NPSH.

1. The Pump > Flow Rate

The flow rate of the pump is defined as the useful volume of liquid distributed by the pump in the time unit.It is generally indicated with the letter Q and is measured in m3/s, or in m3/h, or in l/min.

2. The Pump > Head

The (total) head of the pump represents the increase in energy acquired by 1 kg of liquid between the input andthe output section of the pump itself; this is generally indicated with the letter H and is measured in J/kg or inmetres of carried liquid (m. C.L.). It is much more convenient to speak not of the head but of the manometrichead, indicated as Hman and measured in m C.W. (metres of column of water): saying that a certain pump gives aflow rate of 3 m3/h with a manometric head of 12 m C.W. means that pump can lift a quantity of water amountingto 3 m3/h up to a maximum height of 12 m. The applicable equation is: Hman [m C.A.] = H[m C.L.] * ?[kg/dm3],where ? = volume of the liquid transported.

All pumps are provided with a data plate which clearly indicates, among the other data, the flow rate, manometrichead and their interconnection. However these two parameters are not fixed, but vary inversely to one another:when one increases, the other decreases and vice versa. If the various points of operation of a pump are plotted ona graph, on which the X-axis represents the flow rate and the Y-axis the manometric head, the so-calledcharacteristic curve Q-Hman of the pump is obtained. (fig. 1)


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The characteristic curve may be "flat" or "steep", depending on how the pump has been designed and on thesystem in which the pump is to be fitted. As may be seen in figure 2, the pumps that have a flat characteristiccurve give rise to slight variations in head for strong variations of flow rate, while pumps with a steepcharacteristic curve give rise to slight variations in flow rate for high variations in head. So pumps of the first typewill be preferable when a more or less constant head is desired with a flow rate varying within ample margins(this is the case, for example, of pumps for fire-fighting installations); vice versa, pumps of the second type will be preferable when a more or less constant flow rate is desired with a head varying within a relatively wide field(for example in the case of pumping from wells, where constant flow rates are generally desired even in the presence of high variations in the geodetic difference in level).

Figure 2 - Flat and steep characteristic curves. Figure 1

3. The Pump > Power There is the power supplied by the pump to the liquid, expressed as:Pu[W] = g[m/s2] * ?[kg/m3] * Q[m3/s] * H[m C.L.], where g[m/s2] is the acceleration of gravity, generally equalto 9,81 m/s2.

Then there is the power Pnom absorbed by the pump, that is, in the case of electropumps, the power transferred bythe electric motor to the pump axle.

Then there is the electric power Pabs absorbed by the electric drive motor from the power mains.

Figure 2

4. The Pump > Efficiency

There is the efficiency ? p of the pump, defined as the ratio between the power Pu supplied to the fluid and the power Pnom aabsorbed by the pump (that is the mechanical power transferred by the electric motor): ? p = Pu / Pnom.

Then there is the efficiency ?mot of the electric motor, defined as the ratio between the power absorbed by the pump and that absorbed by the motor:?mot = Pnom / Pass.


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In the case of electropumps we frequently speak of the efficiency of the unit, defined as the ratio between the power supplied to the fluid and the power absorbed by the motor: ?gr = Pu / Pass = ? p* ?mot. It must be stressed thatthe efficiency ?gr of the unit is a very important parameter for an electropumps: the higher its value the less thecost, in terms of electric energy and in money in the long run, that must be borne to have the electropump performa certain job.

5. The Pump > Speed The rotation speed is the number of revolutions performed by the pump in the time unit; this is generally indicatedwith the letter n and measured in rpm.All PENTAX electropumps are fitted with a 2-pole induction motor; considering the average running of themotors and the fact that the electric energy distributed in the mains generally has a frequency of 50 or 60 Hz, thisgives roughly n(50 Hz) = 2750 - 2950 rpm and n(60 Hz) = 3300 - 3550 rpm.

6. The Pump > NPSH (Net Positive Suction Head)

This parameter indicates the pump's inability to create an absolute vacuum, that is the inability of all centrifugal pumps to suck at a height equal to or higher than 10.33 m (which generally corresponds to the value ofatmospheric pressure at sea level).

From the physical point of view, the NPSH indicates the absolute pressure that must exist at the pump intake to

prevent the occurrence of cavitation phenomena. When a pump tries to suck up a certain amount of liquid from adepth greater than that allowed by its characteristics, cavitation occurs: the impeller interrupts the flow of liquidand, as a result, small vapour bubbles are formed; these bubbles implode shortly after being formed, making aloud noise similar to metallic hammer and causing severe damage to the hydraulic parts of the pump.

That is why it is important for every pump manufacturer to indicate clearly, among the characteristics of hismachines, the maximum suction depth, or to supply the curve of the NPSH as a function of flow rate. Themaximum suction depth Hmax and NPSH are linked by the relationship:

Hmax = A - NPSH - Hasp - Hr (m)

dwhere:A = absolute pressure in m on the free surface of the fluid in the suction tank; if fluid is being sucked from an

"open" tank, that is in contact with the atmosphere, A is equal to the atmospheric pressure;Hasp = load loss in the suction pipe in m;Hr = vapour tension of the liquid transported in m.

The NPSH is influenced by the flow rate value: it grows as the latter increases; as a result, in order to return the pump to regular operation it is often sufficient to choke the delivery gate valve suitably, thus reducing the flowrate of the pump.

As may be seen from the equation above, to increase the maximum suction depth of a certain pump the load lossesHsuc of the suction pipe may be decreased: that is why it is always convenient to fit a pipe with the largest possibleinternal diameter at suction.

II. Characteristic Curve of the System - Working Point Curva caratteristica dell'impianto - Punto di lavoro

In a (hydraulic) pumping system, the following may be distinguished:

The suction channel or tank, that is the "environment" from which the pump takes the liquid; The suction duct or pipe through which the liquid is led to the pump (missing only in systems where

the pump body is immersed); The delivery duct or pipe into which the pump sends the liquid; The delivery channel or tank, that is the "environment" into which the pump sends the liquid that it

has lifted.


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The energy required to carry 1 kg of liquid from the suction tank to the delivery tank is:

Hi = (Hm - Ha) + Hg + H p (m)

where:

* Hm e Ha, expressed in C.L., are the pressures on the free surface of the liquid in the delivery tank and in thesuction tank respectively. If both tanks are at atmospheric pressure, the term (Hm - Ha) is equal to zero;

* Hg is the geodetic difference in level, in metres, of the system: the examples given in figure 3 show how itshould be measured;

* H p is the total load losses, in metres, of the suction pipe (if fitted) and of the delivery pipe. Load losses are theenergy losses that take place during movement of the liquid; they may be "continuous" or "accidental". Theformer are those due to friction between the fluid and the pipe whereas accidental losses are due to a variation inspeed (widening or narrowing of the section, mouths and outlets, valves, etc.) and to changes in direction (curves,elbows, etc.). To calculate load losses, graphs and/or tables are generally used that may be easily found in good books on hydraulics or on pumping systems.

While Hm, Ha, Hg generally remain constant as the flow rate varies, the load losses H p increase as the flow rateincreases following a fairly quadratic law: as a result the value of Hi also increases as the flow rate increases.

If a graph is drawn showing the values of Hi as a function of flow rate, the so-called "line of total resistance orcharacteristic curve of the system" is obtained (figure 4). Generally the characteristic curve of the system is plotted by joining a certain number of coordinate points (Q, Hi), bearing in mind that, as we have said, only theterm H p varies as Q varies.


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Figure 3 - A few examples of installation with respective indication of the geodetic difference in level.

Figure 4 - Characteristic curve of the system.

If on the same diagram we show the characteristic curve of a certain system and the characteristic curve of acertain pump, a point of intersection of the two curves is found which defines the working point of that pump inthat system (figure 5).

Figure 5 - Working or operating point of a pump.

From this brief description it may already be deduced that the working point does not depend only on the pump'scharacteristics, but is also a function of the type of system in which the pump is fitted: it is sufficient tomanoeuvre a gate valve fitted on the pump delivery, thus varying the load losses there, or to vary the level of theliquid in the suction or delivery tank, thus varying the geodetic difference in level Hg, to shift the working point toa different capacity.

III. Dimensions and Arrangements of Special Pipes and Pieces


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1) The rated diameters of the pump mouths do not give any reference for establishing the diameters ofthe suction and delivery pipes.

For delivery pipes of limited length, the flow rate and capacity may be fixed according to the following table(approximate values supplied as a guide):

internal diameter (mm): 25 32 40 50 65 80 100 150 200flow rate (m/s) 1,4 1,4 1,5 1,6 1,7 1,8 1,9 2,0 2,1capacity (m3/h): 2,5 4,1 7 11 20 33 54 127 237

For delivery pipes of considerable length (therefore for high power pumping systems), the diameter is chosenaccording both technical and economic criteria.

It is advisable for the delivery pipe to be provided with a check valve and with a regulating valve. The former,which should be upstream from the latter so that it may be inspected and replaced if necessary without emptyingthe delivery pipe, must protect the pump against water hammer and prevent inverse flow though the impeller inthe event of sudden stopping of the unit. The regulating valve, on the other hand, is used to vary the power raised by the machine and therefore to satisfy the requirements of the user.

2) The suction pipe requires greater attention than the delivery pipe, as a mistake in its installation or inchoosing its dimensions may cause serious problems (the major one being cavitation, with all the problems thataccompany it).

To guarantee the best and most efficient suction conditions, this pipe must be as short as possible, vertical orrising towards the pump (so as to avoid air pockets which could cause the pump to become unprimed), withoutchoking or sudden changes in direction.

Save in the exceptional case of complex systems, along the suction pipe there must not be valves of any kindexcept the foot valve fitted at the immersed end of the suction pipe; in the case of Jet self-priming pumps, the footvalve may be replaced by a check valve fitted directly on the suction mouth.

It must also be remembered that, in order to guarantee suction of the liquid to be pumped, this pipe must behermetically closed, especially if there is a high geodetic difference in level at suction. At the same time theremust be no high points where the air and/or gases dissolved in liquid can gather, thus causing an interruption inthe flow; it is therefore best to fit flanged or threaded couplings, discarding solutions that consider cup or bellcouplings which frequently cause an imperfect seal.

To avoid the formation of vortices, and the consequent intake of air with the liquid to be pumped, the input sectionof the suction pipe must be about 0.4 - 1 m below the free suction surface, depending on the dimensions of thesystem.

For short suction pipes the flow rate and capacity values indicated above may be chosen, multiplied by 0.8;however, the internal diameter must never be smaller than the diameter of the pump suction mouth.

3) Each pump should, if possible, have its own suction pipe so that it may be easily excluded from the system ifthe need arises, and also to prevent the entry of air in the suction manifold when the pump is stopped. If a singlesuction pipe has to be designed for several pipes, the delivery check valves must be eliminated and fitted on thesuction mouths instead.

4) Special pieces (such as curves, elbows, derivations and connections, etc.) and various valves should be usedonly if built suitably: for further information on this subject, consult a good book on hydraulics or on pumpingsystems. In all cases remember that:

a. the connections must be accurate so to avoid air re-entry and to prevent the gaskets from reducing theworking section of the pipe passage, increasing its resistance;

b. to choke the capacity, regulate only the gate valves fitted on the delivery pipe and never those on suction.


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IV. Notion on electric motors for electropumps

Electropumps are generally fitted with 2 or 4-pole induction electric motors. Each PENTAX electropump isdriven by an induction motor with a short-circuited rotor (squirrel cage), enclosed and self-ventilated, suitable forcontinuous duty, with 2 poles. The special characteristics of these motors are their simplicity and safety ofoperation, while they are particularly sturdy and inexpensive to run. They may be of the three-phase type or, forlimited power ranges (roughly less than 3 Hp), even single-phase; the latter are generally produced with a permanently in-circuit capacitor.

The characteristics of an electric motor are:

a. rated power and rated current ; b. rated voltage and frequency ; c. power factor ; d. speed ; e. type of duty ; f. insulation class ; g. degree of protection .

1. Electric Motors > Rated Power - Rated Current

The rated power of an electric motor is the mechanical power available to the shaft; it is expressed in Watt (W), inhorse power (1 Hp = 745.7 W) or in metric horse power (1 CV = 736 W): for the sake of convenience it isfrequently presumed that 1 CV = 1 Hp = 750 W.

The rated current is the current absorbed by the motor, fed at rated voltage and frequency, when it supplies therated power.

The rated power differs from the absorbed power depending on the performance of the motor. It must beremembered that the rated power, or current, characterizes a well defined point of operation of the motor: the ratedoperation point. The actual power, or current, absorbed by the electric motor that drives an electropump dependson the point of work of the electropump: in centrifugal pumps, for example, the higher the flow rate, the greaterthe absorbed power.

Due to problems of overheating, and frequently to avoid cavitation, it is of fundamental importance to use anyelectropump within the limits recommended by its manufacturer: only in this way can we be sure of notendangering the efficient functionality and long life of the machine.

2. Electric Motors > Rated Voltage and Frequency

The rated voltage is the line voltage, or voltage between two phases, on the motor terminals at rated power. Itsvalue is considered by the designer when planning the dimensions of the machine: for correct motor function, andtherefore for that of the electropump, the mains voltage must not differ much from this value: on this subject,international regulations require that motor-driven appliances be able to supply their rated power, and therefore tofunction correctly, when they are fed at a voltage that may vary by 5% (6%) of the rated value.

If in a given country the mains voltage has a wide field of variation around a rated value, it is advisable to pointthis out to the manufacturer who may consider the possibility of designing a motor specially to deal with thesecharacteristics.

Other important data which must always be indicated on the machine plate are the rated frequency - generally 50Hz or 60 Hz - and the number of phases; generally single-phase or three-phase induction motors are used. Asspecified above, single-phase induction motors are almost always of the type with permanently in-circuitcapacitor: in this case the data plate will show the capacity of the capacitor and the maximum voltage that it canwithstand.

3. Electric Motors > Power Factor
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The power factor (p.f.) or cos f, generally not known or not considered by "non-technicians", indicates the phasedifference between the vectors representing voltage, on the motor terminals, and the vectors representing thecurrent that it absorbs. This is a very important parameter for an induction motor as, together with the performance, it indicates the quality of the motor: its value is all the higher when the designer establishes "good"dimensions without speculating too much on cost (using good quality laminations, allowing for ample dimensionsof the pack and the number of leads in the winding, etc.).

It must also be remembered that, in the various countries, the electric energy distribution company requires that

users have a minimum value of power factor: for values below this limit the user has to pay an excess charge forthe energy consumed. The distribution company also has the power to enforce the user to alter his systems so as to bring the p.f. to a value that is not below the set limit: the lower the p.f. of a system, the higher the cost that must be incurred to bring it up to the minimum set value (or, to use the technical term, to correct the power factor of thesystem).

4. Electric Motors > Speed

See the paragraph on Pump Speed .

5. Eclectric Motors > Type of Duty

By duty of any electric machine is meant (the definition of) the load to which the machine is subjected, including(if applicable) the time intervals devoted to starting, electric braking, idling and pause time, their duration andsequence in time.

Without pausing to describe the various types of duty defined by the standards (continuous, limited duration,intermittent, etc.), we shall simply stress that each PENTAX electropump is driven by an induction motor, whichmay be single-phase or three-phase depending on the model, of enclosed and self-ventilated type, suitable forcontinuous duty, that is able to supply the performance declared on the data plate without interruption.

6. Electric Motors > Insulation Class

During operation a dielectric declines, that is it gradually loses its ability to perform the task for which it isintended. We therefore speak of the life of an insulation, by which we mean the time during which the insulation's properties are kept above set values so that it can perform the functions for which it was intended.

The life of the materials used for the insulation of electric machines depends on numerous factors of differentkinds: thermal, chemical, mechanical and electrical factors. Among these the most important are thermal andelectrical stress.

As regards the machines, the value of the working temperature is highly important because the length of itsefficient working life depends on this. In fact, although the insulations each need a limit operating temperaturethat must never be exceeded, the length of their efficient working life is all the greater the lower the temperature atwhich they are made to operate.

On the basis of these concepts, solid insulating materials are divided into classes that are conventionally identified

by a letter and distinguished by the maximum acceptable temperature during operation.

The most widespread insulation classes and their respective maximum temperatures are the following:

insulation class: A E B F Hlimit temperature (C): 105 120 130 155 180

Since, at the same power, the temperature of the various parts of an electric machine depends on the ambienttemperature, the international standards refer more frequently not to limit temperature but to the maximumadmissible overtemperature with respect to ambient temperature. More precisely, with regard to electric machines,a conventional ambient temperature is defined and limits are fixed for the overtemperatures of the windings, onthe basis of the insulation class used.
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Standard IEC 335-1 / 335-2-41, referring to electric pumps for domestic and similar uses, sets an ambienttemperature of 25C (which may occasionally reach 35C) and defines the following limits for the overtemperatures of the windings:

insulation class: A E B F Hlimit temperature (C): 75 90 95 115 140

Standard IEC 34-1, referring to rotating electric machines and therefore applicable to electric motors, sets aconventional ambient temperature of 40C and defines the following limits for the overtemperatures of thewindings:

insulation class: A E B F Hlimit temperature (C): 60(65) 75 80(85) 105(110) 125(130)The values in brackets refer to machines with a power of less than 600 W.

To conclude we may sum up by saying that the insulation class of a given electric motor is indicative of themaximum overtemperature, with respect to the ambient temperature, that may be reached by the windings of the

motor: a high admissible overtemperature indicates the use of "quality" insulating material in machineconstruction, making the machine suitable for use in particularly severe installations.

PENTAX electropumps are driven by electric motors with class B or class F insulation, depending on the size ofthe motor.

7. Electric Motors > Degree of Protection

Like other electric machines, electric motors too - and therefore electropumps - are classified according to theclosing system, that is the protection against the entry of solid and liquid bodies.

The degree of protection of the casings of rotating electric machines is defined by the Standard with the initials IP(International Protection) plus two figures which may (at the manufacturer's discretion) be followed by one or twoletters. As summed up in figure 6, each position in the code has a value of its own.

Figure 6 - Structure of the IP code according to international standards. The letter "X" replaces one, the other, orboth figures when these are not requested or where, in a text, they do not influence the topic dealt with.

- The first characteristic figure serves as dual indication:

a) protection of persons against access to dangerous parts, that is electrically active parts or moving mechanical parts; b) protection of the machine against the penetration of solid foreign bodies.

In progression, the figures indicate gradually higher degrees of protection. It is also understood that a machinewith, for example, degree 4 also complies with the lower degrees of protection (from 0 to 3).

- The second characteristic figure indicates protection against the harmful penetration of water.


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- The purpose of the additional letter is to designate the level of inaccessibility of the machine casing to fingers orhands, or objects held by a person; this letter also denotes a strictly accident-prevention function and must be usedonly if the protection against access is higher than that defined with the first characteristic number.

- The purpose of the supplementary letter is to indicate particular conditions concerning the type of machine or itsuse.

All PENTAX electropumps are characterized by degree of protection IP44, that is they are protected against the

access, to dangerous parts, of a wire or of solid bodies with dimensions higher than or equal to 1 mm (1stnumber), and against splashes of water coming from any direction (2nd number).

PHN DCH I. bm> Gii thiu

Khi mt cht lng, c th l nng hoc lnh, c "chuyn" trong h thng, my bm c s dng. Nicch khc, v mt cch thch hp hn v mt k thut, bm l mt my thy lc lm vic m c chc nng t(tng s c kh) nng lng ca mt cht lng; ny c ngha l bm chuyn n cc cht lng, chy qua n, tr phm vi c cho php bi hiu qu ca n, mt phn ca nng lng m n nhn c t ng c l

Ti thi im ny chng ti c th thc hin mt s phn bit quan trng da trn ng c li xe:

- Chng ti ni v electropump mt khi nng lng c hc cn thit cho vic bm chuyn c cung cpmt ng c in;

- Chng ti ni v ng c mt my bm khi nng lng c hc ny c cung cp bi mt ng c nhit (c t trong, ng c, vv).

y chng ta phi i ph vi c quyn electropumps- v thm vo, chngti s tm dng m t cc cim quan trng nht ca ng c in m a - v:

1) ng c in ang c s dng rng ri nht;

2) Pentax sn xut v th trng electropumps.

Xem xt cc nh ngha, chng ti c th tin hnh vi m t ca chng ti bm, bt u vi nhng yu t cm t hot ng ca mnh:

Lu lng;

1. ng u; 2. in; 3. hiu qu; 4. tc ;

5. NPSH. 1. Cc bm> Flow Rate

T l dng chy ca bm c nh ngha l khi lng hu ch ca cc cht lng phn phi bi cc my bmcc n v thi gian.

N thng c ch nh vi Q l th v c o bng m3 / s, hay trong m3 / h, hoc trong l / pht.

2. The bm>. Trng

The (tng cng) ng u bm i din cho tng nng lng mua 1 kg cht lng gia phn u vo v u ra camy bm t; ny thng c ch nh vi ch H v c o bng J / kg hoc trong mt thc cht lng (m. C


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N c nhiu thun tin hn ni chuyn khng phi ca ngi ng u nhng manometric ca ngiu, ch l Hngi n ng v o bng m CW (mt ct nc): ni rng mt my bm mt t l nht nh cho dngchy ca 3 m3 / h vi u manometric ca 12 m CW c ngha l bm c th tng ln mt lng nc chim nm 3 / h ln n mt cao ti a 12 m. Phng trnh p dng l: Hngi n ng [m CA] = H [m CL] *? [Kg / dm3], u? = Khi lng vn chuyn cht lng.

Tt c cc my bm c cung cp vi mt tm d liu m r rng cho thy, trong s cc d liu khc, t llng, u manometric v kt ni ca h Tuy nhin hai thng s khng c nh,. Nhng khc nhau nghch vi

nhau: khi mt tng, vic gim khc v ngc li. Nu nhng im khc nhau ca hot ng ca mt my bmc v trn mt th, m trn cc trc X i din cho t l lu lng v Y cc trc u manometric, cl ngi n ng QH ng cong c trng ca bm l c ly. (Hnh 1)

Cc ng cong c tnh c th c "phng" hay "dc", ty thuc vo cch bm c thit k v trnthng my bm, trong l c trang b. Nh c th c nhn thy trong hnh 2, cc my bm c mt ngcong phng c trng cho n cc bin th tng nh trong u cho cc bin th mnh ca tc dng chy, tkhi my bm vi mt ng cong c trng dc cho n cc bin th tng nh mc lu lng cao cho ccth trong u . V vy, my bm ca cc loi hnh u tin s c a thch hn khi mt nhiu hn hay t lin tng u l mong mun vi t l lu lng khc nhau trong vng ra d dt (y l trng hp, v d, cc m bm cha chy ci t); ngc li, my bm ca Loi th hai s thch hp hn khi c nhiu hn hoc t hnhng s t l lu lng c mong mun vi mt u khc nhau trong mt lnh vc tng i rng (v d ttrng hp bm t ging, ni m t gi dng chy lin tc ni chung l mong mun ngay c trong s hin dinca cc bin th cao S khc nhau trc a cp ).

Hnh 2 - phng v dc ng cong c trng.

Hnh 1

3. 3 Cc bm>. Power

C l ngun cung cp bi cc my bm cht lng, biu hin nh: P u [W] = g [m/s2] *? [Kg / m3] * Q [m3 / s] * H [m CL], ni g [m / s2] l s tng tc ca trng lc, ni chung l

nh nhau n 9,81 m / s2.

Sau , c Pnom hp th nng lng bng cch bm, c ngha l, trong trng hp electropumps, chuyn giaoquyn lc ca ng c in bm trc.

Sau , c P inabs hp th bi cc ng c in t ngun in nng.

Hnh 2

4. Cc bm> Hiu qu

Khng c hiu qu khng?P ca bm, nh ngha l t s giau P ngun cung cp n cc cht lng v P innom aabsorbed bng bm ( l s chuyn giao quyn lc c kh ca ng c in): p =? Pu / P nom.

Sau , c hiu qumot ca ng c in, nh ngha l t l gia s hp th nng lng bng my bm v? Rhp th bng xe my:mot =? Pnom / ass P.

Trong trng hp ca electropumps chng ti thng xuyn ni v hiu qu ca n v, nh ngha l t l gin cung cp cho cc cht lng v quyn lc hp th bng xe my:gr =? Pu / ass P = p *??Mot. N phi c nhnmnh rng hiu qugr ca n v? L mt tham s rt quan trng cho mt electropumps: gi tr ca n cng caocng t chi ph, v nng lng in v tin bc v lu di, m phi chu c electropump thc hin mt cng nht nh.


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trong :

* H m e H mt, biu hin CL, l nhng p lc trn b mt min ph ca cc cht lng trong cc bn cha v ph phi ti cc b ht tng ng. Nu c hai thng l lc p sut khng kh, thut ng ny (Hm - H mt) l bng skhng;

* H g l s khc bit cp trc a, trong mt, ca h thng: v d c a ra trong 3 con s hin th nhno cn c o lng;

* H p l tng s cc khon l ti, trong mt, ca ng ht (nu c trang b) v cc ng ng phn phi. Loadtn tht nng lng l nhng thit hi xy ra trong qu trnh chuyn ng ca cht lng; h c th c "linhay "tnh c". iu th nht l nhng ngi do ma st gia cc cht lng v ng ng trong khi thit hi do nn l do mt bin th tc (m rng hay thu hp ca b phn, ming v cc ca hng, van, vv) v nhngi trong ch o (ng cong, ci ch, vv). tnh ton thit hi ti, th v / hoc cc bng ny thng cs dng c th d dng tm thy trong cun sch tt v thy lc, hoc trn h thng bm.

Trong khi Hm, H a, H g ni chung vn khng i khi t l lu lng khc nhau, nhng thit hi ti tng p H khitl tng lu lng sau mt lut kh bc hai: kt qu l gi tr ca Hi cng lm tng nh lm tng t l lu lng .

Nu mt th c rt ra cho thy gi tr ca Hi nh l mt chc nng t l lu lng, ci gi l "dng khng

tng s hoc ng cong c trng ca h thng" l c (hnh 4). Ni chung cc ng cong c trng ca hthng l v bng cch gia nhp mt s lng nht nh, phi hp cc im (Q, Hi), mang rng, nh chng ti ni, ch c p H thut ng khc nhau nh Q khc nhau.

Hnh 3 - Mt vi v d v ci t tng ng vi cc du hiu ca s khc bit cp ta.

Hnh 4 - c im ng cong ca h thng.

Nu trn cng mt s chng ti hin th cc ng cong c trng ca mt h thng nht nh v ng

c tnh ca mt my bm nht nh, mt im giao nhau ca hai ng cong c tm thy trong xc im lm vic ca my bm m trong h thng (hnh 5).

Hnh 5 - Lm vic hoc im iu hnh ca mt my bm.

T ny m t ngn gn n c th c suy lun rng cc im lm vic khng ch ph thuc vo c tnhmy bm, nhng cng l mt chc nng ca loi h thng my bm, trong c trang b: l mt vn uyn van trang b trn cc ca khu Bm phn phi, do thay i cc thit hi c ti, hoc thay i mccht lng trong thng ht hoc giao hng, v th khc nhau S khc nhau trc a trong Hg cp, chuyn ilm vic cho mt cng sut khc nhau.

Kch thc v III. Sp xp cc ng c bit v Pieces

1) Cc ng knh nh gi cao nht ca ming bm khng a ra bt k ti liu tham kho chvic thit lp cc ng knh ca ng ht v giao hng. i vi ng ng phn phi di hn ch, t l lu lng v kh nng c th c c nh theo bng sau

tr gn ng nh hng dn cung cp mt):

ni b, ng knh (mm): 25 32 40 50 65 80 100 150 200 Lu lng (m / s) 1,4 1,4 1,5 1,6 1,7 1,8 1,9 2,0 2,1 cng sut (m3 / h): 2,5 4,1 7 11 20 33 54 127 237

i vi ng ng phn phi di ng k (do cho nng lng cao, h thng bm), ng knh l c hai chn theo tiu ch k thut v kinh t.


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l khuyn khch cho cc ng ng phn phi c cung cp vi mt van kim tra v vi mt van tit. iu th nht, cn c thng ngun t sau n c th c kim tra v thay th nu cn thit m kh cc ng phn phi, phi bo v cc my bm nc chng li ba v ngn chn dng chy ngc ca Cntrong trng hp dng t ngt ca n v. Van iu tit, mt khc, c s dng thay i quyn lc ln ln bng my v do p ng cc yu cu ca ngi s dng.

2) Cc ng ng ht i hi s ch ln hn cc ng phn phi, nh l mt sai lm trong tin trnh ci thoc trong vic la chn kch thc ca n c th gy ra vn nghim trng (thnh phn chnh l cavitation,

tt c cc vn m i km vi n). m bo cc iu kin ht tt nht v hiu qu nht, ng ny phi c cng ngn cng tt, dc hoc t

pha my bm ( trnh cc ti kh no c th lm cho my bm tr thnh unprimed), m khng nght th hthay i t ngt hng.

Tit kim trong trng hp c bit ca cc h thng phc tp, dc theo cc ng ng ht khng phi lca bt c loi tr cc van chn trang b m mnh vo cui ca ng ht; trong trng hp ca Jet t l p sn lotmy bm, van chn c th c thay th bng mt van kim tra c gn trc tip vo ming ht.

N cng phi nh rng, m bo ht ca cht lng c bm, ng ng ny phi c hermetically ca, c bit l nu c mt s khc bit trong trc a cao cp ti ht. ng thi phi c khng c im cao mkhng kh v / hoc cc kh ha tan trong cht lng c th thu thp, gy gin on trong mt dng chy, n l d tt nht ph hp bch hoc khp ni ren, discarding gii php xem xt vic tch hoc chung khp ni thng xuyn gy ra mt con du khng hon ho.

trnh s hnh thnh ca vortices, v tiu th cc consequent ca khng kh vi cht lng c bm, phn vo ca ng ht phi c khong 0,4-1 m di mt ht min ph, tu theo kch thc ca h thng.

i vi ng ht ngn t l lu lng v kh nng gi tr ch nh trn c th c chn, nhn vi 0,8, tuy nhng knh ni b khng bao gi phi nh hn ng knh ca ming ht bm.

3) Mi my bm nn, nu c th, c ng ht ring ca mnh n c th d dng b loi tr khi h thng,cn thit, v cng ngn chn vic nhp cnh ca khng kh trong cc ng ht khi bm c ngng li. Numt ng ht n phi c thit k cho mt s ng ng, vic phn phi cc van kim tra phi c loi c gn vo ming ht thay th. 4) c bit ming (nh l ng cong, ci ch, derivations v kt ni, vv) v van khc nhau nn c s d

ch khi c xy dng ph hp: cho bit thm thng tin v ch ny, tham kho kin mt cun sch tthy lc, hoc trn h thng bm. Trong mi trng hp, hy nh rng:

a. Cckt ni phi chnh xc nh vy trnh ti ha khng kh, nhp cnh v ngn chn cc Phe M vic gim phn lm vic ca qua ng ng, tng sc khng ca n;

b. To choke nng lc, iu chnh cc van ca khu ch c trang b trn ng ng phn phi v khn bao gi nhng ngy ht.

IV. Khi nim v ng c in cho electropumps

Electropumps thng c gn vi 2 hoc 4- pole ng c cm ng in. Mi electropump Pentax l li xe camt ng c cm ng vi mt rotor ngn mch (lng sc), km theo v t thng gi, ph hp vi nhim v lintc, vi 2 cc. Nhng c im c bit ca cc ng c ca h l n gin v an ton ca hot ng, c bitrong khi chng c vng chc v r tin chy. H c th l trong ba pha loi, hoc, i vi cc phm viquyn lc hn ch (khong hn 3 Hp), giai on-thm ch duy nht; ci sau ny thng c sn xut vi mtvnh vin trong-t mch.

Cc c tnh ca mt ng c in l:

a. c nh gi cao nng lc v nh gi cao nht hin nay; b. c nh gi cao in p v tn s; c. cng sut;
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d. tc ; e. loi thu; f. lp cch nhit; g. vn bng bo h.

1. Electric Motors> Rated Power - Rated Current

c nh gi cao sc mnh ca mt ng c in l nng lng c hc c sn trc ca n c thtrong Watt (W), trong sc nga (1 HP = 745,7 W) hoc in nga s liu (1 CV = 736 W): cho v li ch ca stin li n thng c coi l 1 CV = 1 HP = 750 W.

Cc nh gi cao nht hin nay l hin ti hp th bng xe my, n in p v tn s nh gi cao nht, khingun cung cp sc mnh nh gi cao nht.

c nh gi cao sc mnh khc vi quyn nng hp th tu thuc vo hiu sut ca ng c ny. N phic ghi nh rng sc mnh nh gi cao nht, hoc hin ti, characterizes mt im c xc nh r hot ca xe my: im hot ng nh gi cao nht. Quyn lc thc t, hoc hin ti, hp th bi cc ng c in cmt a electropump ph thuc vo im lm vic ca cc electropump: trong bm ly tm, v d, cao hn tdngchy, cng ln sc mnh hp thu.

Do cc vn ca qu nng, v thng xuyn trnh cavitation, n c tm quan trng c bn s dng belectropump trong gii hn khuyn co ca nh sn xut ca mnh: ch bng cch ny chng ta c th chc ckhng gy nguy him cho cc chc nng hiu qu v cuc sng lu di ca my.

2. 2. Electric Motors> in p v tn s

in p nh gi cao nht l in p ng dy, hoc in p gia hai giai on, trn cc nh ga xe in ti gi cao nht. Gi tr ca n c coi l ca nh thit k khi lp k hoch kch thc ca my: cho chc nng cang c chnh xc, v do cho rng ca cc electropump, in p ng ng khng phi khc vi nhiu t tr ny: trn ch ny, cc quy nh quc t yu cu c -khin thit b gia dng c kh nng cung cp in ca hnh gi cao nht, v do n chc nng chnh xc, khi chng c nui ti mt hiu in th m c th knhau bi 5% (6%) ca gi tr nh gi cao nht.

Nu mt quc gia c in p ng ng c mt lnh vc rng ln ca cc bin th xung quanh mt gnh gi cao nht, bn nn n thi im ny ra cc nh sn xut nhng ngi c th xem xt kh nng thimt ng c c bit i ph vi nhng c trng ny.

D liu quan trng khc m lun lun phi c ghi trn cc tm my c tn s nh gi cao nht- thng 50Hz hoc 60 Hz- v s lng ca giai on; thng n pha hoc ba giai on c cm ng c s dng. Theoquy nh trn, n ng c giai on gn nh lun lun cm ng ca cc loi vi vnh vin trong mch t -:trong trng hp ny cc tm d liu s cho thy nng lc ca cc t in v in p ti a m n c th c.

3. Electric Motors> Power Factor

Cc s cng sut (pf) hoc cos f, thng khng c bit hoc khng c xem l do "phi k thut", ch rakhc bit gia cc giai on vect i din cho in p, trn bn xe, v cc vector i din cho hin ti m nth. y l mt tham s rt quan trng cho mt ng c cm ng nh, cng vi hiu nng, n cho thy chlng ca xe my: gi tr ca n l tt c nhng cao hn khi thit k cc thit lp "tt" kch thc m khngsuy on qu nhiu vo chi ph (s dng laminations cht lng tt , cho php kch thc phong ph ca cc gv s lng dn u trong quanh co, vv).

N cng phi nh rng, trong cc quc gia khc nhau, cc cng ty phn phi in nng lng yu cu ngidng c gi tr ti thiu ca mt s cng sut: cho cc gi tr di gii hn ny ngi dng s phi tr mt k ph d tha cho nng lng tiu th. Cng ty phn phi cng c sc mnh thi hnh cho ngi dng thay ih thng ca mnh em li cho pf mt gi tr khng phi l di mc gii hn t: cng thp pf ca mthng, cao hn chi ph phi c pht sinh mang li n ln n gi tr ti thiu (hoc, s dng nhng thutk thut, sa cc yu t sc mnh ca h thng).
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4. Electric Motors> Speed

Xem on trn bm tc .

5. Eclectric Motors> Type of Duty

Bi nhim v ca bt k my in l c ngha l (nh ngha ca) nhng ti m my tnh ny l phi chu, bgm (nu c) trong khong thi gian dnh cho vic bt u, phanh in, Idling v thi gian tm dng, thi g

ca h v trong trnh t thi gian. M khng cn tm dng m t cc loi thu c xc nh bi cc tiu chun (lin tc, gii hn thi gian

tc, vv), chng ti ch n gin l phi nhn mnh rng mi electropump Pentax l li xe ca mt ng c cng, c th c n pha hoc ba giai on ty thuc vo m hnh, trong km theo v t loi thng gi, ph hvi nhim v lin tc, m c th cung cp hiu sut tuyn b trn tm d liu m khng b gin on.

6 Electric Motors>. Insulation Class

Trong qu trnh hot ng ca mt in mi t chi, c ngha l n dn dn mt kh nng thc hin nhim vn c d nh. Do chng ti ni v cuc i ca mt cch nhit, do chng ta c ngha l trong sut thgian cch in ca cc ti sn s c gi trn cc gi tr t n c th thc hin cc chc nng m

c d nh. i sng ca cc ti liu c s dng cho cch in ca my in ph thuc vo nhiu yu t ca cc loinhau: nhit, ha cht, c kh v in yu t. Trong s ny, quan trng nht l nhit in v cng thng.

Cng lin quan n cc my mc, gi tr ca nhit lm vic l rt quan trng bi v chiu di ca cuc sca mnh lm vic hiu qu ph thuc vo iu ny. Trong thc t, mc d mi insulations cn mt nhit hotng gii hn m khng bao gi phi c vt qu, chiu di ca cuc sng lm vic hiu qu l tt c cnhn nhit h c lm hot ng.

Trn c s cc khi nim, vt liu cch in rn c chia thnh cc lp hc c quy c xc nh bi mt chv phn bit bng nhit chp nhn c ti a trong qu trnh hot ng.

Ph bin nht ca cc lp cch nhit v nhit ti a tng ng ca h l nh sau:

lp cch in: A E B F H gii hn nhit ( C): 105 120 130 155 180

K t khi, ti cng mt quyn lc, nhit ca cc b phn khc nhau ca mt my in ph thuc vo nhimi trng, cc tiu chun quc t cp thng xuyn hn khng gii hn nhit nhng overtemperature admissible ti a i vi nhit mi trng xung quanh. Chnh xc hn, i vi n my inhit mi trng xung quanh thng c nh ngha v gii hn c nh cho overtemperatures ca cc cudy, trn c s ca lp cch in c s dng.

Tiu chun IEC 335-1 / 335-2-41, cp n my bm in s dng trong nc v tng t, t ra mt nhi mi trng ca 25 C (m i khi c th t n 35 C) v xc nh cc gii hn sau cho nhit trn ccun dy:

lp cch in: A E B F H gii hn nhit ( C): 75 90 95 115 140

Tiu chun IEC 34-1, cp n cc my in lun phin v do p dng cho cc ng c in, nhit thng lp mt mi trng xung quanh ca 40 C v xc nh cc gii hn sau cho overtemperatures ca ccun dy:

lp cch in: A E B F H
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gii hn nhit ( C): 60 (65) 75 80 (85) 105 (110) 125 (130)

Cc gi tr trong ngoc n ch n my vi mt sc mnh ca hn 600 W.

kt lun chng ti c th tng hp bng cch ni rng cc lp cch nhit ca mt ng c in cho l ch caovertemperature ti a, i vi nhit mi trng xung quanh, m c th t c ca cc cun dy ca xe mmt overtemperature admissible cao cho thy vic s dng "cht lng" vt liu cch in trong my xy dlm cho my thch hp s dng trong ci t c bit nghim trng.

Electropumps Pentax c thc y bi ng c in vi lp B hoc cch in F lp, ty thuc vo kch c cxe my.

7 Electric Motors>. Bng cp ca Bo v

a) Ging nh cc my khc in, ng c in qu- v do electropumps- c phn loi theo cc h thngng, l s bo v chng li cc entry ca cc c quan rn v lng.

Mc bo v ca v bc ca my in lun phin c xc nh bi cc tiu chun vi tt IP (Quc Bocng vi hai con s m c th (theo ca nh sn xut) c theo sau bi mt hoc hai ch ci. Theo tng cng bng con s 6, mi v tr trong cc m c gi tr ring ca mnh.

Hnh 6 - Cu trc ca m IP theo tiu chun quc t. Cc l th "X" thay th mt trong nhn phng php khc, hoc c hai con s khi y khng phi l yu cu hay u, trong mt vbn, chng khng nh hng n ch x l.

- Con s c im u tin phc v nh ch kp: mt bo v) ca nhng ngi chng li quyn truy cp vo cc phn nguy him, l in t ang hot ng b phn hoc di chuyn cc b phn c kh;

b) bo v my tnh chng li s xm nhp ca cc c quan rn nc ngoi.

Trong tin trnh, cc s liu cho thy mc cao dn bo v ny cng hiu rng vi mt my tnh, v d, cn

4 mc tun th cc vn bng bo h thp (0-3).. - Con s c tnh th hai cho bit bo v chng li s xm nhp c hi ca nc.

- Mc ch ca bc th b sung l ch mc kh tip cn ca v my ngn tay hoc bn tay, hoc ctng c t chc bi mt ngi; th ny cng l bt mt tai nn nghim chnh chc nng v cng tc phchng phi c s dng ch khi bo v chng truy cp l cao hn mc quy nh vi s c im u tin.

- Mc ch ca bc th b sung l cho bit iu kin c th lin quan n cc loi my hoc s dng ca

Mi electropumps Pentax c c trng bi mc bo v IP44, c ngha l h c bo v chng li truyvo, phn nguy him, mt dy in hoc ca cc c quan rn vi kch thc cao hn hoc bng 1 mm (1st

v chng li splashes nc n t mi hng (2nd s). Figure 3

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