expansion tanks
DESCRIPTION
Expansion TanksTRANSCRIPT
&-elbL
update February 2005
Expansion Tanks
Expansion Tanks - strona 1
Expansion Tanks - strona 2
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
Expansion Tanks - strona 4
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
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
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
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
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
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
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
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
ERP 320
ERP 416
ERP 385
ERP RET
ERP - Q
Expansion Tanks - strona 13
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
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
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
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
"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
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
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
"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
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
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
Expansion Tanks - strona 24
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
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
Precharge pressure (bar)
&-eIŹ7L
Expansion Tanks - strona 27
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
&-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