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Project

Project Consultant

Client

Contractor

Subject

Design By

Reference Output

References

[1] 2000 ASHRAE systems and equipment handbook

[2] 2003 ASHRAE journal - Annex 02

[3] Pg.15, Installation and Maintenance Manual (IM 1044-1)-Models

WSC,WDC,WCC,HSC - May 2010 Annex 03

[4] Table 3, pg.6.5, 1997 ASHRAE fundermentals handbook - Annex 04

Expansion tank sizing[1] Equation for diaphram type expansion tank :

chapter 12

eq.14

System volume

See Annex 01 System volume 50 m3

[2] Determining of minimum pressure

1. Low pressure point (LPP) in the system is the heighest point on the return line just as it

drops down to the pump2. Pmin = 27.58 kPa

3. Tank is installed at the suction of primary chilled water pump

4. Static pressure rise = 48.75 m = 478.24 kPa

5. Frictional pressure drop taken as 0 kPa

6. Minimum tank initial gauge pressure (P1)= 505.82 kPa

[2] Determining of maximum pressure

[3] 1. Standard pressure rating of all components (Pma) = 1034 kPa

The critical pressure point (CPP) in the system is lowest point in the system on dischargeside of the secondary pump

2. Pressure relief valve (PRV) is installed near the expansion tank

= 0 kPa

Because there is no height difference between expansion tank and CPP

= 255.06 kPa

Frictional pressure loss from CPP to PRV is roughly the head of secondary pump

= 778.94 kPa

6. Static pressure difference ( Ps,PRV-tank) = 0 kPa

Calculation

3. The static pressure difference between CPP and

Pressure relief valve (Ps,CPP-PRV)

4. The frictional pressure drop is secondary pump head

(Pf,CPP-PRV)

Tank is downstream

of the LPP

5. Pressure relief valve set point (Prv) = Pma+ Ps,CPP-PRV -

Pf,CPP-PRV

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Reference OutputCalculation

7. Frictional pressure drop from PRV to tank ( Pf,PRV-tank) = 0 kPa

8. Maximum gauge pressure (Pmax) = 778.94 kPa

Data for the tank sizing equation

Symbol Value Unit

System volume Vs 50 m3

Minimum temperature t1 7 C

Maximum temperature t2 32 C

Atmospheric pressure Pa 101.33 kPa

Minimum pressure P1 505.82 kPa

Maximum pressure P2 778.94 kPa

[4] Specific volume at higher temperature v1 0.001 m3/kg

[4] Specific volume at lower temperature v2 0.001005 m3/kg

Linear coefficient of thermal expansion 1.17E-05 m/mKt2-t1 t 25 C

Required tank volume (Vt)

[1] Vt >= 0.66 m3 Vt >=

chapter 12 Vt >= 664.33 ltrs 664.33

eq.14 ltrs

Conclusion

Expansion vessel volume (ie. 1000 l) requested by the employer's requirement of

tender document is acceptable.

Parameter

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Reference OutputCalculation

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