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User Manual Series F-BO-AFE70
solenoid valve's operation time during a Purging process, in order to obtain the size of the air ves-
sel.
The prerequisite for the validity of the tables in this chapter is a constant input overpressure of
the Purging unit during the Purging process; to ensure this an appropriately dimensioned pres-
sure-limiting valve is required.
The calculation of the stated values is based on a pipe between compressed-air vessel and Pur-
ging unit that is very short and has a low velocity loss. Therefore, if the distances are large, see to
it that the compressed-air supply pipe is generously dimensioned in order to keep the pressure
losses low.
In order to estimate the required size of the compressed-air vessel, proceed as follows:
First determine on the basis of the specifications in Chapter 4.1 the required input overpressure of
the Purging unit.
Now use Table 6 or 7 to determine the air vessel's required sub volume (in litres per second of the
Purging process) at the intersection of the Purging unit's required input overpressure and the avail-
able air vessel overpressure. For the required total vessel volume you have to multiply the determ-
ined size by the solenoid valve's planned total opening time during the Purging process.
An example should explain the approach:
For your system you need an F-BO-AFE70-2 with an input overpressure of at least 0.5MPa (5 bar).
Furthermore, your planned air vessel overpressure of the compressor is 1.0MPa (10bar).
So, to determine the size of the compressed-air tank for an Automatic Purging Unit F-BO-AFE70-2
you use Table 6. The Purging unit's required input overpressure of 0.5MPa (5bar) and the air vessel
overpressure of the compressor of 1.0MPa (10bar) result in a vessel sub volume of 9.4 litres per
second of opened solenoid valve.
Depending on the Purging process that is to be set according to Chapter 9.5.1 in the course of com-
missioning, the solenoid valve's total opening time during the Purging process amounts to 3×3=9
seconds (for the short Purging process) or 5×5=25 seconds (for the long Purging process).
So in the case of the short Purging process and an air vessel overpressure of 1.0MPa (10bar), an air
vessel volume of at least 9.4×9=84.6 litres is needed, in the case of the long Purging process an air
vessel volume of at least 9.4×25=235 litres is needed.
I56-4252-010
D200-104-00
Chapter 4 • Pneumatic components – dimensioning
17
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