Unigas HRX2060, Manual Of Installation - Use - Maintenance

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PART III: OPERATION
41
Oil pressure switch adjustment
Follow the below instruction, according to the pressure switch installed.
Minimum oil pressure switch (when provided)
The minimum oil pressure switch on the inlet line, checks that the pressure does not drop below a default value. The pressure switch
must be set, say, at 10% under the pressure at the nozzle.
Maximum oil pressure switch
The oil pressure switch on the return line, checks that the pressure does not exceed a default value. This value must not be higher
than the maximum acceptable pressure on the return line (this value is reported on the specification table). A pressure change on the
return line could affect the combustion parameters: for this reason, the pressure switch must be set, say, at 20% over the pressure
recorded during the combustion adjustment. The factory setting is 4 bar.
It is recommended to verify that the combustion parameters are within the range of acceptable values even against a pressure varia-
tion that gets close to the limit of the pressure switch.
This check should be carried out along the whole range of the burner output.
In case of inacceptable values, reduce from 20% to 15% the overpressure; later on, repeat the adjustments described above.
Pressure governor on return line
Pressure governor works between two different pressure values. The minimum pressure value is set by the minimum output setting
pressure screw under the plug 1; The maximum pressure value is set by the plunger stroke “V” and the modulation is obtained with the
movement of the piston in-out. The valve also control the flow in the following way: the higher pressure in the valve has, as consequen-
ces, the less flow through it and also the lower pressure in the valve is, the higher flow through it. On the other side in the nozzle return
line the higher pressure has like consequence the more oil pulverized in the nozzle
ATTENTION: Regulator’s capacity with minimum output setting pressure depends on adjustment of the conic pin.
Avoid a piston stroke higher than 10mm. In this peculiar case with a high value of minimum output setting pres-
sure can cause the block of the piston - conic pin and break the pin.
HEX6
Trafag Picostat 9B4..
Pressure
Return
Legend
P = Return pressure from spill-back nozzle
R = Return to tank
V = Plunger
1 = Minimum output setting pressure
2 = Modulation: 8-9 stroke
P R
P R
1 2
V