Operating manual- SAB 355 (including ATEX)
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004059 en 2019.11
6.10
Automatic oil return valve
Fig. 17
Note:
Valve inlet and outlet are marked on the valve housing with "in" and “out”.
Function
The function of the automatic oil return valve, EVRB, is to return the separated oil in the fine sepa-
rator to the compressor.
Oil and gas from the fine separator flow into the oil return valve at pos. 1, through the filter, pos.
2, and via the nozzles, pos. 7 and 8, and back to the compressor through the outlet, pos. 5, see
Fig. 18.
The gas and oil flow through the nozzles, pos. 7 and 8, is adapted to the spring force of pos. 9 as
well as the viscosity difference between the oil and the gas. Consequently, the pressure loss of
the gas flow through the nozzle, pos. 7, is unable to move the piston, pos. 7.
However, the pressure loss of the oil flow through the nozzle, pos. 7, is able to move the piston,
pos. 7.
Thus the spring force, pos. 9, is equalised and a transverse bore, pos. 10, with a considerably
larger bore than pos. 7, will open.
Because the bore is larger, oil collections at the oil return valve inlet can quickly be removed.
When the oil has been removed, the gas flow will rise, and the piston, pos. 7, will close the trans-
verse bore. The gas flow will be lowered to a minimum.
Through the sight glass, pos. 6, it is possible to watch the oil return. As a small amount of gas will
always pass through the nozzle, pos. 7, gas bubbles will be visible.
The valve can be serviced by closing the stop valves, pos. 3 and 4.
5
1
5
1
3
4
6
2
5
1: Inlet G1/4”
2: Filter
3: Stop valve, inlet side
4: Stop valve, outlet side
5: Outlet G1/4”
6: Sight glass