expansion tanks

29
&-elbL update February 2005 Expansion Tanks Expansion Tanks - strona 1

Upload: aleksandar-veliki

Post on 23-Oct-2015

71 views

Category:

Documents


1 download

DESCRIPTION

Expansion Tanks

TRANSCRIPT

Page 1: Expansion Tanks

&-elbL

update February 2005

Expansion Tanks

Expansion Tanks - strona 1

Page 3: Expansion Tanks

Expansion tanks

ER - CE series ERCE series ERL - CE series ERP series SANY series D - CE series

Sizing of an expansion tank with a fixed bladder - technical data

ERL-DAC series

Sizing of an auto-pressurised expansion tank - technical data

Some examples of installation

(flyleaf of the back cover) Universal diagram

4 6 8 10 13 14

16 18

21 24

Expansion Tanks - strona 3

Page 5: Expansion Tanks

Expansion tanks

Expansion tanks are devices designed to absorb the volume change of water or some other liquids, thus allowing the correct operation of a heating plant during all its operative phases.

Elbi produces closed expansion tanks composed by a tank in sheet steel and a bladder in synthetic material which separates the heating circuit from a chamber previously charged with air. Expansion tanks with a bladder, which are available from 5 to 5.000 litres, are constructed by using quality sheet steels

according to UNI-EN regulations and welded according to some strict qualitative standards; they are produced on automated lines, welded with procedures and approved weld materials, equipped with bladders in special rubber used against heat and ageing which are resistant up to 110° C (all of them are

produced by ELBI); they are previously charged at a pressure of 0.5 - 1.0 -1.5 bars according to the static height of the water column.

Once the construction has been completed, all the models are subjected to a hydraulic test with a pressure of 1.5 times higher than the designed one.

There are also some versions constructed according to the most important European regulations in force.

Elbi bladders

Elbi produces all the bladders which mounts on its own equipment, as for the production it makes exclusive use of modern injection presses, the most advanced ones in this sector. Dies designed by the Elbi technical department ensure the complete compatibility with tanks. All the bladders are tested by the

company's quality control service at the end of the production run. Bladders which are used in the ERL series are constructed by applying an exclusive process which allows to obtain the exact dimensions corresponding to the tank's actual volume, thus eliminating every kind of mechanical stress during the

operation.

Their mixing is the result of some studies and researches carried out directly by the Elbi technical department.

ELBI reserves the right of making changes to its products and data shown in this catalogue without notice. Technical information is indicative of the product features. All dimensions are subject to the standard tolerance.

Expansion Tanks - strona 5

Page 6: Expansion Tanks

ER - CE series

The available models from 2 to 24 litres are designed to be installed in different types of plant.

Besides, they are available in special versions, constructed according

4

- to the most important international regulations: CE, WRAS, UDT, etc.

Characteristics

• Working temperature: -10°-=- + 99°C

• Sturdy structure in high-quality steel, designed to endure for a long time.

• Painting with long life epoxy powders.

• Bladders in special rubber with those characteristics which ensure better performances and a longer life.

• In compliance with essential safety requirements of directive 97/23/EC.

• CE marking (type ER2 - ER5 without CE marking).

Capacity litresMaximumPrecharge

Modelworking pressure barpressure barDe mmH mm01Packaging mm

ER2281,51462301/2"150 x 150 x 240

ER5581,52052253/4"210 x 210 x 250

ER8 CE881,52053003/4"210 x 210 x 320

ER12 CE1281,52703003/4"280 x 280 x 310

ER18 CE1881,52704103/4"280 x 280 x 450

ER24 CE2481,53203553/4"330 x 330 x 375

1MPa = 10 bar

2 to 24 litres

r-- I

01

1 UQ

Expansion Tanks - strona 6

Page 7: Expansion Tanks

Selection of the expansion tank

The table simplifies the choice of the ELBI expansion tank to be installed in hot water systems. The selection of the tank can be effectuated starting from the system's total capacity or from the plant's power, taking into consideration an average content of 12 litres per 1000 Kcal/h of power and a plant's

maximum working pressure of 3 bars.

■ Temperature difference AT = (90 - 14)°C ■ A coefficient of expansion 0,035

Model Precharge Plant height Tank's Tank's

pressure meters volume absorption Total water Heat-generator's

acceptable capacity content in power

bar m litres % the plant

litres Kcal/h kW

5

Expansion Tanks - strona 7

Page 8: Expansion Tanks

ERCE series

35 to 500 litres

The available models from 35 to 500 litres are designed to be installed in the different types of plant.

Besides, they are available in special versions, constructed according to the most important international regulations: CE, WRAS, UDT, etc.

Characteristics:

• Working temperature: -10°-=- +99°C

• Sturdy structure in high-quality steel, designed to endure for a long time.

• Painting with long life epoxy powders.

• Bladders in special rubber with those characteristics which ensure better performances and a longer life.

• In compliance with essential safety requirements of directive 97/23/EC.

• CE marking.

ModelCapacity litresMaximum working pressurePrecharge pressureDeH01Packaging

barbarmmmmmm

ERCE 35*35101,5400390410 x 410 x 410

ERCE 50*50101,5400500410 x 410 x 535

ERCE 8080101,5400840410 x 410 x 860

ERCE 100100101,5500795510 x 510 x 830

ERCE 150150101,55001.025510 x 510 x 1040

ERCE 200200101,56001.100610 x 610 x 1100

ERCE 250250101,56501.190660 x 660 x 1210

ERCE 300300101,56501.265660 x 660 x 1290

ERCE500500101,57751.4251" 1/4785 x 785 x 1440

*Standard without base, upon request with feet. 1MPa = 10 bar

6

Expansion Tanks - strona 8

Page 9: Expansion Tanks

Selection of the expansion tank

The table simplifies the choice of the ELBI expansion tank to be installed in hot water systems. The selection of the tank can be effectuated starting from the system's total capacity or from the plant's power, taking into consideration an average content of 12 litres per 1000 Kcal/h of power.

PrechargePlant'sPlantTank'sTank'sTemperature difference AT = (9014)°C

pressuremaximumheightacceptableabsorptionA coefficient of expansion 0,035

ModelworkingvolumecapacityTotal waterHeat-generator's

pressurecontent inpower

barbarmlitri%the plant

litresKcal/hkW

11017,65050341.90048,72093

ER CE 351,531513,13737431.20036,27907

2208,82525120.90024,30233

110255071459.50069,18605

ER CE 501,531518,83853771.40052,03488

22012.52535729.75034,59302

11040501.14395.250110,7558

ER CE 801,5315303885771.40083,02326

220202557147.60055,34884

11050501.428119.000138,3721

ER CE 1001,551538381.08690.500105,2326

220252571459.50069,18605

110100672.857238.000276,7442

ER CE 1501,551587582.486207.000240,6977

22075502.143178.600207,6744

110133673.800317.000368,6047

1,515116583.314276.000320,9302

ER CE 2002520100502.857238.000276,7442

2,52583422.371197.600229,7674

33066331.886157.200182,7907

110178715.086423.800492,7907

1,515160644.571380.900442,907

ER CE 2502520143574.086340.500395,9302

2,525125503.571297.600346,0465

330107433.057254.800296,2791

110214716.114509.500592,4419

1,515193645.514459.500534,3023

ER CE 300620171574.886407.000473,2558

2,525150504.286357.200415,3488

330128433.657304.800354,4186

1,515321649.171764.300888,7209

220285578.143678.600789,0698

ER CE 5002,5625250507.143595.300692,2093

330215436.143512.000595,3488

3,535178365.086427.000496,5116

7

Expansion Tanks - strona 9

Page 10: Expansion Tanks

ERL - CE series

750 to 5000 litres

Ci

Thanks to an ELBI exclusive design, expansion tanks with an interchangeable bladder of the ERL series represent a valid solution for the installation in plants with high water contents which till now made us use traditional tanks without any bladders or install series of smaller tanks.

The ERL series is available in models from 750 to 5000 litres thanks to an exclusive designed bladder. The ERL series' bladders ensure a practically unlimited life, since they are produced in order to operate without any stretching. Besides, expansion tanks are available in special versions, constructed

according to the most important international regulations: CE, UDT, CZ, etc.

Characteristics:

• Working temperature: -10°^+99°C.

• Sturdy structure in high-quality steel, designed to endure for a long time.

• Painting with long life epoxy powders.

• Bladders in special rubber with those characteristics which ensure better performances and a longer life.

• In compliance with essential safety requirements of directive 97/23/EC.

• CE marking.

8

CapacityMaximum workingPrecharge

ModellitrespressurepressureDeH01

barbarbarmmmm

ERL 7507501016no80019602" M

ERL 10009801016no80023402" M

ERL 20002.0001016no1.1002750G 3"

ERL 30003.0001016no1.2503100G 3"

ERL 50005.00010-no1.5503420G 3"

1MPa = 10 bar

Expansion Tanks - strona 10

Page 11: Expansion Tanks

Selection of the expansion tank

The table simplifies the choice of the ELBI expansion tank to be installed in hot water systems. The selection of the tank can be effectuated starting from the system's total capacity or from the plant's power, taking into consideration an average content of 12 litres per 1000 Kcal/h of power and a plant's

maximum working pressure of 6 bars.

Temperature difference AT =(90 - 14)°C

ModelPrechargePlant heightTank's acceptableTank's absorptionA coefficient of expansion 0,035

pressurevolumecapacityTotal waterHeat-generator's

content inpower

barmlitres%the plant

litresKcal/hkW

1.5154826413.7711.148.0001334,884

2204305712.2861.024.0001190,698

ERL 7502.5253755010.714893.0001038,372

330321439.171765.000889,5349

3.535268367.657638.000741,8605

2205715716.3141.360.0001581,395

2.5255005014.2861.190.0001383,721

ERL 10003304304312.2861.024.0001190,698

3.5353573510.200850.000988,3721

440286288.171681.000791,8605

2201.1425732.6282.719.0003161,628

2.5251.0005028.5712.380.0002767,442

ERL 20003308574324.4862.040.0002372,093

3.5357143520.4001.700.0001976,744

4405712816,3141.359.0001580,233

2201.7145748.9704.080.0004744,186

2.5251.5005042.8573.571.0004152,326

ERL 30003301.2854336.7143.059.0003556,977

3.5351.0713530.6002.550.0002965,116

440857282.4852.040.0002372,093

2202.8575781.6286.802.0007909,302

2.5252.5005071.4285.952.0006920,93

ERL 50003302.1424361.2005.100.0005930,233

3.5351.7853551.0004.250.0004941,86

4401.4282840.8003.400.0003953,488

9

Expansion Tanks - strona 11

Page 12: Expansion Tanks

ERP series

6 to 24 litres

ERP tanks are available from 6 to 24 litres for a total number of 22 models.

The range of tanks proposed with the ERP series has been designed in order to ensure the greatest reliability. They are available in the TUV and WRAS approved version.

Characteristics:

• Sturdy structure in high-quality steel, designed to endure for a long time.

• Painting with long life epoxy powders.

• Bladders in special rubber with those characteristics which ensure better performances and a longer life.

• Working temperature: -10°^+90°C

• Precharge pressure: 1 bar

• In compliance with directive 97/23/EC (PED)

10

ModelCapacity litresMaximum working pressure barDimensions mmDeH mm01

ERP 320/663/320943/4"

ERP 320/883/3201213/4"

ERP 320/10103/3201313/4"

ERP 320/12123/3201653/4"

ERP 385/773/385833/4"

ERP 385/883/385983/4"

ERP 385/10103/3851083/4"

ERP 385/12123/3851393/4"

ERP 385/14143/3851463/4"

ERP 416/663/416653/8"

ERP 416/883/416753/8"

ERP 416/10103/416903/8"

ERP RET 663516x196/953/4"

ERP RET 883516x196/1103/4"

ERP RET 10103516x196/1243/4"

ERP RET 12123516x196/1523/4"

ERP - Q 773436 x 344/773/8"

ERP - Q 10103436 x 344/971/2"

ERP - Q 12123436 x 344/1171/2"

ERP - Q 14143436 x 344/1321/2"

ERP - Q 16163436 x 344/1471/2"

ERP - Q 18183436 x 344/1551/2"

ERP - Q 20203436 x 344/1621/2"

ERP - Q 24 24 3 436 x 344 / 177 1/2"

1MPa = 10 bar

Expansion Tanks - strona 12

Page 13: Expansion Tanks

ERP 320

ERP 416

ERP 385

ERP RET

ERP - Q

Expansion Tanks - strona 13

Page 14: Expansion Tanks

SANY seríes

0,5 to 4 litres

Replaceable butyl bladder slim type tanks

ELBI's New Slim type Tanks serve the double purpose of Shock Absorber and Domestic Hot Water storage vessel in wall hung and floor standing boilers.

The SANY product line has been developed by ELBI to respond to OEM's and contractors' demand for plumbing cushions that can be fitted in small and narrow spaces. The product design and appliance-finish paint render these vessels suitable for use in open/ visible spaces of the house as well.

13

Products specifications:

• Replaceable Butyl Bladder.

• White appliance- finish color.

• 3A" GAS connection.

• Working temperature: -10°C -f +99°C.

• Plastic screen flange protection.

ModelCapacity litresDiameter (mm)Height (mm)Spud length (mm)Maximum working pressure (bar)Precharge pressure (bar)Packaging (mm)

SANY0,50,59017030103-

SANY119024030103-

SANY22903803010395 x 95 x 390

SANY33905303010395 x 95 x 540

SANY44906703010395 x 95 x 680

Expansion Tanks - strona 14

Page 15: Expansion Tanks

D - CE series

2 to 500 litres

14

Polifunctional sanitary vessels with bladder

Polifunctional sanitary vessels with fixed bladder are designed to be fitted both into sanitary system as expansion tanks,

suitable to absorb the water expansion volume generated by a changing temperature, as well as tanks for cold water sanitary systems.Both applications are possible thanks to the exlusive Top-Pro® anti-corrosion treatment which ensures the protection against corrosion of the inner surface of the fitness of

all parts in contact with water.

Installing a D series sanitary vessel considerably cuts down operating costs, while suppressing the discharge function of the safety valve.

Characteristics:

• Equipped wiyh a fixed alimentary bladder in Butyl that ensures permanent isolation of the air cuscion from the water;

• Internal protection of the water connection in Nylon 66;

• Guaranteed for 3 years (all the D series);

• In compliance with essential safety requirements of directive 97/23/EC;

• CE marking.

ModelCapacity litresMax workingPrecharge0DeHPackaging

pressurepressuremmmmmm

(bar)(bar)

D 221031/2"146230150 x 150 x 240

D 551033/4"205225210 x 210 x 250

D 881033/4"205300210 x 210 x 320

D 11111033/4"270300280 x 280 x 310

D 18181033/4"270410280 x 280 x 450

D 24241031"320355330 x 330 x 375

D 35351031"400390410 x 410 x 410

DV 50501031"400570410 x 410 x 610

DV 80801031"400825410 x 410 x 860

DV 1001001031"1/4500779510 x 510 x 830

DV 1501501031"1/45001.007510 x 510 x 1040

DV 2002001031"1/46001.076610 x 610 x 1110

DV 3003001031"1/46501.251660 x 660 x 1290

DV 5005001031"1/47751.410785 x 785 x 1440

1MPa = 10 bar

Expansion Tanks - strona 15

Page 16: Expansion Tanks

Method used for selecting the expansion tank

ModelPlant heightPrech. press.Tank accept. vol.Tank absorbt. cap.Plant water

mbarlt%content (lt)

303,00,94580

D 2353,50,73560

404,00,63050

303,03,443290

D 8353,52,936245

404,02,328195

303,04,743400

D 11353,53,936335

404,03,228270

303,07,743660

D 18353,56,436550

404,05,128440

303,010,343880

D24353,58,636735

404,06,928590

303,015,0431285

D35353,512,5361070

404,010,028860

303,021,4431835

DV 50353,517,9361530

404,014,3281225

303,034,3432935

DV 80353,528,6362445

404,022,8281955

303,042,9433670

DV 100353,535,7363060

404,028,6282445

303,064,3435505

DV 150353,553,6364585

404,042,9433670

303,085,7437340

DV 200353,571,4366115

404,057,1284890

303,0128,64311010

DV 300353,5107,2369175

404,085,7287340

303,0214,34318345

DV 500353,5178,63615290

404,0142,82812230

15

Max press. =6 bar

t inlet =10°C

t outlet =50°C

This table semplifies the choice of the ELBI expansion tank to be installed in the hot sanitary water circuits.

Expansion Tanks - strona 16

Page 17: Expansion Tanks

Sizing of an expansion tank with a fixed bladder

Technical data

The expansion tank's useful volume must be calculated according to a maximum working pressure (pe), corresponding to the safety valve's adjustment pressure, diminished by a quantity equal to the difference value between the expansion tank and the safety valve, if the latter is situated downwards,

otherwise increased if the safety valve is located upwards.

The expansion tank's useful volume must correspond to the expansion volume (Ve), in practice the maximum change of the water volume which can occur in the plant is the following one:

Ve= C x (u2 - u-,) [litres]

where:

u2 = water specific volume at the maximum operative temperature litres/kg. ux = water specific volume at the minimum operative temperature litres/kg. C = plant's total capacity (boiler, pipes, charges, etc.) kg.

The Vt total volume of the closed expansion tank with a bladder is calculated according to the following formula:

p 1 . p [litres] Pe

p

In order to avoid calculating 1--fL the table 2 reporting the results of these calculations has Pe

been drawn up. Pe

where:

Ve= plant's expansion volume litres

Pp= precharge pressure of the expansion tank bar (absolute pressure) Pe= plant's maximum working pressure or adjustment pressure of the safety valve bar (absolute pressure)

The precharge pressure must correspond to the hydrostatic pressure in the tank's installation place, whereas the difference between the cut in pressure of the safety valve (pv) and the working pressure (pe) is usually 10% of the cut in pressure.

A tolerance of 10% of the plant's total volume is allowed in the choice of the tank to be installed.

Expansion Tanks - strona 17

Page 18: Expansion Tanks

"water specific volume at different temperatures"

Table 1

TuTuTuTu

°Clitres/Kg°Clitres/Kg°Clitres/Kg°Clitres/Kg

- 101,00186161,00103361,00632801,0290

- 51,00070181,00138381,00706851,0324

01,00013201,00177401,0078901,0359

21,00003221,00221451,0099951,0396

41,00000241,00268501,01211001,0434

61,00003261,00320551,0145101,0515

81,00012281,00375601,01711201,0600

101,00027301,00435651,01981301,0795

121,00048321,00497701,02271401,0795

141,00073341,00563751,02581501,0903

Table 2 a

Max workingprecharge pressure (bar)

pressure11,522,533,544,55

1,50,2

20,3330,167

2,50,4290,2860,143

30,50,3750,250,125

3,50,5560,4440,3330,2220,111

40,60,50,4000,30,20,1

4,50,6360,5450,4550,3640,2730,1820,091

50,6670,5830,50,4170,3330,250,1670,083

5,50,6920,6150,5380,4620,3850,3080,2310,1540,07

60,7140,6430,5710,50,4290,3570,2860,210,14

6,50,7330,6670,600,5330,4670,40,3330,260,2

70,750,6880,6250,5630,50,4380,3750,310,25

7,50,7650,7060,6470,5880,5290,4710,4120,350,29

80,7780,7220,6670,6110,5560,50,4440,380,33

8,50,7890,7370,6840,6320,5790,5260,4740,420,36

90,80,750,70,650,60,550,50,450,4

9,50,810,7620,7140,6670,6190,5710,5240,470,43

100,8180,7730,7270,6820,6360,5910,5450,50,45

Table 2 b

Max workingprecharge pressure (bar)

pressure5,566,577,588,599,5

60,07

6,50,130,06

70,180,120,06

7,50,230,170,110,06

80,280,220,160,110,06

8,50,310,260,210,160,10,05

90,350,30,250,210,150,10,05

9,50,380,330,280,240,190,140,10,05

100,410,360,320,270,230,180,140,090,045

Expansion Tanks - strona 18

Page 19: Expansion Tanks

ERL-DAC series

Auto-pressurized expansion tanks

300 to 5000 litres

18

FUNCTION

Traditional expansion tanks are used in heating plants in order to limit overpressures which are generated by the liquid's volume variation inside the closed circuit whenever temperature changes. In fact, the air cushion of the expansion tank serves as a "lung" according to a ratio established by Boyle law.

The DAC (Dynamic Air Cushion) system has been designed to solve in a simple, safe and economically advantageous way the problems that can occur to the designer of a heating plant in the following cases.

• Exceptionally high water volume in the plant.

• Limited dimensions of the boiler room.

• Very reduced differences between the plant's min./max. pressures.

In these cases, the possibility to exploit completely the tank's volume as a water reserve allows to save considerably both in the installation costs and in the management and maintenance ones.

The groups of the ERL/DAC series allow to achieve this aim, since the expansion tank's sizing is not calculated according to the maximum value of water acceptance in the tank (Boyle law), but only according to the total expansion volume of the water contained in the plant. The pressurisation level is

constantly checked by the electronic control panel according to the set min./max. pressure data.

CHARACTERISTICS OF THE STRUCTURE

The ERL/DAC system is composed by:

• An expansion tank of the ERL-D series CE approved.

• A control unit with a microprocessor (MCP) and an incorporated compressor CE approved.

EXPANSION TANKS OF THE ERL-D SERIES

They are constructed in high-quality sheet steel and they are available from 300 to 5000 litres. The models from 750 to 5000 litres are equipped with a bladder of the "all volume" type, whose dimensions ensure a practically unlimited life of the bladder itself, thus allowing to work under nearly null conditions

of mechanical stress. They are traditionally available in the Export version at 10 bars max working pressure. Upon request they can be manufactured with different pressure more than 10 bar according to the most important international standards (TUV, AS ME, BS).

MCP control unit

Expansion Tanks - strona 19

Page 20: Expansion Tanks

DIMENSIONAL DATA ERL-D tanks

MCP control unit

ModelCapacity ltDe mmH mm0 1Maximum pressure bar

ERL-300 D3006501.3101" 1/4 M10

ERL-500 D5007751.4851" 1/4 M10

ERL-750 D7508002.0252" M10

ERL-1000 D1.0008002.3552" M10

ERL-2000 D2.0001.1002.820G 3"10

ERL-3000 D3.0001.2503.170G 3"10

ERL-5000 D5.0001.5503.490G 3"10

ModelSuction capacity lt/minABH

mmmmmm

MCP1114610490900

MCP3300610490900

MCP5650660560935

MCP71.0508006651.080

Working temperature: -10°C + 99°C

• The tanks 750, 1000, 2000, 3000 and 5000 litres are endowed with an upper and lower flanged opening.

1 All the compressors are equipped with a IP-54

type protection.

The compressor's maximum pressure: MCP1 = 8 bars, the other ones = 10 bars. ' The compressors mounted on the MCP1 unit are single-phase, all the others are three-phase.

19

MCP unit - Technical characteristics

Electric powerVoltageNoiseCapacity Compressor

Model(HP/KW)(V)(db)(lit/min.)

MCP1 220/501 / 0,7522065114

MCP1 220/601 / 0,7522065114

MCP1 110/601 / 0,7522065114

MCP3 380/50/602,5 / 1,838065300

MCP5 380/505,5 / 438070650

MCP5 380/605,5 / 438070650

MCP7 380/5010 /7,5380701.050

MCP7 380/6010 /7,5380701.050

Expansion Tanks - strona 20

Page 21: Expansion Tanks

"MCP" CONTROL UNIT

COMPRESSORS - Technical data

The MCP unit is equipped with an analogue microprocessor and it is endowed with a compressor, a liquid crystals display, some solenoid valves and some filters for the air outlet and inlet in the tank. The MC unit controls the system operation, by keeping under control the set minimum and maximum

pressure data, the compressor and solenoid valves operation. There are four versions in order to satisfy the different types of the compressors' current and power supply.

• MCP1 - with a compressor of 0.75 kW single-phase

• MCP3 - with a compressor of 1.8 kW three-phase

• MCP5 - with a compressor of 4 kW three-phase

• MCP7 - with a compressor of 7.5 kW three-phase

The usually mounted compressors are provided, already inside the unit, with preliminary controls. Four models with powers from 0.75 to 7.5 kW are provided in order to satisfy the most installation requirements. In the event it is necessary to use a compressor with a higher working pressure or with a higher

suction index, which is not provided in traditional models, consult the company for getting a suitable model to the plant's requirements.

On request, some versions with tropicalised motor are available.

The MCP1 unit is available with single-phase supply (110/220V 50/60 Hz); whereas the other models are endowed with a three-phase supply at 380 V.

20

Description of the system operation

PHASE 1

When the system is off, therefore with the water at ambient temperature, the boiler is switched off, the compressor is in the OFF position as well as the solenoid valves and EV-2, the plant is in the static phase as well as the pressure inside the expansion tank.

PHASE 2

The boiler becomes operative, the water volume inside the plant increases with the consequent pressure increase of the air cushion inside the expansion tank. When the maximum pressure reaches the set value, the EV-2 solenoid valve opens with the consequent air outlet through the SIL-1 silencer; the

temperature reaches the designed maximum value and the boiler is switched off.

PHASE 3

The boiler is still off for the provided temperature difference, the plant slowly cools and therefore the water volume diminishes with the consequent pressure decrease of the air cushion inside the tank. When the pressure reaches the set minimum value, the compressor becomes operative by letting air in the

tank until reaching the set maximum pressure. When the compressor is switched off, the solenoid valve opens by discharging the compressor's head (thus allowing a subsequent soft start without any efforts by the motor).

PHASE 1

to the plant

Expansion Tanks - strona 21

Page 22: Expansion Tanks

Sizing of an auto-pressurised expansion tank

Technical data

Tank's sizing

The sizing of the expansion tank is calculated only according to the total expansion volume of the water contained in the plant, increased by 20% in order to leave a margin of working and safety to the air cushion. The air cushion pressure is selected according to the static height (h), which corresponds to

the difference expressed in meters between the highest point of the plant and the water inlet coupling in the expansion tank, plus a margin of 3 m for the deaeration.

Example

Qk= 3200kWTs =

h= 18m

TM= 90°CVd =

Ti= 10°C

Plant's data Boiler's power Static height

Delivery maximum temperature Water inlet temperature

If the water contents is 13L/KW, the water volume of the plant will be: Vi = 3200 x 13 = 41600 L

From the table concerning the coefficients of the water expansion we will get: Expansion % of the water at 90°C n = 3,59 %

Expansion % of the water at 10°C n2 = 0,04 %

(Tab.2)

The Ke coefficient of expansion will be:

Ke = ■

3,59 - 0,04 100

Therefore, the total water expansion will be: Ve = 41600 x 0,0355 = 1477 litri

Example for calculating the suction index

(valid for most plants)

plant's water volumeVi= 28169L

minimum temperatureTm= 80°C

maximum temperatureTM= 90°C

temperature increaseDt= 10°C

water inlet temperatureTi= 10°C

specific heatC= 1 Kcal /Kg x °C

water volume at 90°C W= 0,965 Kg/L (tab.)

13 x 0,965 x 1 x 10 x 60

100

from the table about the coefficients of expansion (table 2) we can get: expansion % of the water at 90°C n = 3,59% expansion % of the water at 80°C80°C nl = 2,90%

K =

K =

(n - n1)

100

(3,59 - 2,90)

100

= 0,0069

Vd = 28169 x 0,0069 = 194,36 L

Therefore, the tank's optimum capacity for the involved plant will be: 1,477 + 20% = 1,772 litres.

The model with a higher capacity, that is the ERL 2000 model, must be selected. As 1 bar corresponds to 10 meters of the water column and the static height is 18 m, the water column's height will be 21 m (taking into consideration 3 meters for the deaeration), to which corresponds a pressure of 2.1 bars.

According to the pressure - heat power diagram (fig.1), the CP-1 single-phase compressor corresponds to the 2.1 bar pressure and to the 3200 kW heat power. The suitable supply and control unit is MCP1. Therefore, the system will be the following one: ERL-2000D coupled with a MCP1 unit.

Choice of the compressor - Calculation of the flow index Introduction

The total water volume in a heating plant is proportional to the generator's heat power. In a modern heating system, there are on average 13 litres of water per 1000 Kcal/h.

(1) Vs = 13 L/1000 Kcal / h

Calculation of the TS expansion time

(2) Ts = Vs x W x C x Dt where Vs = 13 L / 1000 Kcal / h

W = water volume at the designed maximum temperature Kg/L C = specific heat Kcal/Kg x °C Dt = temperature increase °C

Calculation of the VD water expansion volume relevant to the DT temperature increase

(3) Vd = Vi x K

where Vi = water volume in the plant

K = coefficient of the water expansion according to the DT temperature increase

Calculation of the If flow index

(4) If = Ve / Ts

where If = If - flow index in 1./min.

Calculation of the actual suction index of the compressor (CFM)

(5) CFM = If x Kr

where Kr = Kr = 1.1 is a coefficient under the worst suction conditions, at the suction temperature of 30°C and relative humidity of 100%.

If = 19943 6 = 25,81 L / mm.

CFM = 25,81 x 1,1 = 28,39 = 28,4 L /'mm. L'espansione totale dell'acqua nell'impianto è Ve = 28169 x Ke

21

total water expansion at 90°C total water expansion at 10°C

n = 3,59% n2 = 0,04%

Ke =

Ke =

(n - n2)

1 0 0

(3,59 - 0,04)

1 0 0

= 0,0355

Ve = 28169 x 0,0355 = 1000 L

Therefore, it is possible to affirm that in the most plants it is necessary to use a compressor with a suction index of CFM = 28.4 L/min. per 1,000 L of expanded water at the atmospheric pressure. In order to size correctly the compressor, it is necessary to compare the suction index with the designed

pressure of the expansion tank, taking into consideration that the result "Pressure multiplied by Volume" is a constant value when the pressure is absolute. Therefore, if the pressure in the expansion tank must be kept at 2.5 Bars, remembering that the atmospheric pressure is about 1 Bar, we will get:

CFM =

1 + 2,5 1

x 28,4 = 99,4 L / mm.

In that case, it is necessary to select a compressor with a CFM suction index which is higher than 99.4 L./min.

As for heating plants with current parameters that vary from 11 to 14 litres per kW, use the diagram reported below for selecting the type of compressor.

For pressures which are higher than 10 bars, consult the company.

Expansion Tanks - strona 22

Page 23: Expansion Tanks

TAB. 2

TAB. 3

22

Diagram usedfor selecting the type of compressor

1 23456789 10 11 12x10 KW

Plant heat power Qk

Temperature °C Only water Anti-freeze Anti-freeze Anti-freeze Anti-freeze Anti-freeze

10% 20% 30% 40% 50%

TAB. 4 TYPE OF TANK ACCORDING TO THE PLANT'S WATER VOLUME (m3) AND THE MAXIMUM WORKING TEMPERATURE (°C)

Coefficients of the water expansion expressed in % (with or without addition of anti-freeze glycol)

Expansion Tanks - strona 23

Page 25: Expansion Tanks

Some examples of installation

Traditional installation with solar integration

TO UTILITIES

-tfc—12T-^D-Ät-

7 5 4 7 9

"-Wo

COLD WATER SUPPLY

BLOWDOWN

LEGEND

1-ELBI water heater 2-Boiler

3-D expansion tank 4-Circulation pump 5-Clapet check valve 6-Air valve 7-Gate valve 8-Magnesium anode 9-Thermometer 10-Resistor 11-Pressure gauge 12-D expansion tank

INTEGRATION CIRCUIT WATER OUTLET

LEGEND 1-Boiler

2-Safety valve 3-ERE expansion tank 4-Circulation pump 5-Clapet check valve 6-Air valve 7-Gate valve 8-Thermometer 9-Pressure gauge

10-Radiator

LEGEND

1-ELBI water heater 2-Safety valve 3-D expansion tank 4-Circulation pump 5-Clapet check valve 6-Pressure reducer 7-Air valve 8-Gate valve 9-Magnesium anode 10-Thermometer

Expansion Tanks - strona 25

Page 26: Expansion Tanks

Universal diagram used for selecting the tank

ELBI expansion tanks

ERL 1000 ERL 750

ERE/C 500

ERE/C 300 ERE/C 250 ERE/C 200

ERE/C 150 ERE/C 100

ERE/C 80

ERE/C 50 ERE/C 35

o o o o

o o o o

O O O Li".

f\ CN i—I

>^0 OO go OO 2a\cor"-

Expansion volume expressed in litres

300000

Expansion Tanks - strona 26

Page 27: Expansion Tanks

Precharge pressure (bar)

&-eIŹ7L

Expansion Tanks - strona 27

Page 28: Expansion Tanks

How to use the universal diagram

Determination of the expansion tank according to the plant's water content

The initial data used to determine the expansion tank's capacity are the following ones, namely:

• plant's static pressure or precharge pressure (absolute pressure);

• maximum working pressure of the plant (absolute pressure);

• water mean temperature;

• plant's capacity.

As you know already the plant's capacity, draw a horizontal line until intersecting the water mean temperature line "A-B".

From the point "B", draw a vertical line up to the above graph.

Since you know already the precharge pressure and the plant's maximum pressure,

it is necessary to find the intersection point of the two right lines "C" and, starting

from this one, draw a horizontal line until reaching the graph on the side.

In the intersection point of these two right lines "X" you find the expansion tank

necessary for the plant.

1,5

Precharge pressure (bar)

XL,_______

C

ERE/C 100 tank's area *\Maximum working

pressure (bar) \'

^ Plant's power (Kcal/h)

i

B_______1500 2000A

^-------

Water temperature3000M eet ' Mean water content

in heating plants ^»<w

Determination of the expansion tank according to the plant's power

The initial data used to determine the expansion tank's capacity are the following ones, namely:

• plant's static pressure or precharge pressure (absolute pressure);

• maximum working pressure of the plant (absolute pressure);

• water mean temperature;

• plant's power.

Since you know already the power, draw a vertical line until intersecting the right line relevant to the mean water content of the plant "A". Starting from the point "A", draw a horizontal line until intersecting the water mean temperature line "AB". From the point "B", draw a vertical line up to the above graph.

Since you know already the precharge pressure and the plant's maximum pressure, it is necessary to find the intersection point of the two right lines "C" and, starting from this one, draw a horizontal line until reaching the graph on the side. In the intersection point of these two right lines "X" you find the

expansion tank necessary for the plant.

Expansion Tanks - strona 28

Page 29: Expansion Tanks

&-EÜ7L

Elbi s.p.A. via Buccia, 9 - 35010 Limena (Padova) tel. 049 88 40 677 - fax 049 88 41 610 Internet http:\\www.elbi.it • e-mail: [email protected]

Expansion Tanks - strona 29