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Flamco Baseflex 8L - 35L

Flamco Baseflex Expansion

Vessels 8L - 35L

Flamco carries a wide range of expansion vessels, equipped with innovative technology. Both the steel shell and the membrane are made of top quality materials and guarantee a long service life. Expansion Vessels are for use in pressurised heating systems and permit the absorption of increases in volumes within the system due to temperature rises in the heating medium. The Baseflex expansion vessel comes in a range of sizes from 8 Litres through to 35 Litres in capacity.


  • Deep Drawn Steel Shell
  • EPDM Diaphragm
  • Each Vessel is Factory Tested
  • Red Colour
  • Nitrogen Gas Pre-Charge
  • In Accordance with EN13831
  • CE Approved
Technical Data:  
Vessel Material: Deep Drawn Steel Shell
Diaphragm Material: EPDM (Non Replaceable)
Sizes: 8L, 12L, 18L, 25L & 35L 
Colour: Red (RAL3002)
Maximum Pressure: 6 bar
Pre-Charge Nitrogen Pressure: 1.5 bar
Maximum System Temperature: 120ºC
Diaphragm Temperature Range: -10 - 70ºC
Conforms To: EN 13831 & PED 2014/68/EU
Approvals: CE Approved



Which Vessel to Choose?

Note: Based on a total system volume (with a 3 bar safety valve)

- Formula 1:

Vu = Va x Vn


- Vu = Useful Volume

- Va = Total Content of Installation

- Vn = Percentage of expansion dependant upon the average temperature. Co-efficient to be applied as a function of the average temperature:

a) 40°C = 0.77

b) 60°C = 1.20

c) 70°C = 2.26

d) 80°C = 2.96

e) 85°C = 3.21

f) 90°C = 3.59

g) 95°C = 3.94

- Formula 2:

n = (Final Pressure + Ata. Pressure) – (Factory Set Pressure + Ata. Pressure)
(Final Pressure + Ata. Pressure)


- n = Pressure Factor

- Ata. = Atmospheric Pressure (1bar)

- Formula 3:

Vt = Vu


- Vt = Total Volume of Expansion Vessel

- Vu = Useful Volume (from formula no.1)

- N  = Pressure Factor (from formula no.2)


The total volume of the installation is 350 litres and has a static head of 10m. The average operating temperature is 80°C and the system is fitted with a 3 bar safety valve i.e. final pressure. Find a suitable Reflex Expansion Vessel?

1)   Vu = 350 x 2.96 = 10.36 litres

2)   Note: = Factory set Pressure is 1 bar

n = (3+1) – (1+1) = 0.5

3)   Vt = 10.361 = 20.72 litres


From the catalogue we can see that a 25 litre normal type or a 24 litre flat type would be suitable for the system described above. For further details please contact our sales department.

Print Page Data Sheet

Flamco Data Sheet