15
Pipe heating system
Pipe heating system must be provided, that is a system to heat pipes and plant components to mantain the viscosity in the pumping lim-
its. Higher the oil viscosity and lower the ambient temperature, more necessary the pipe heating system.
Inlet minimum pressure of the pump (both for supplying system and burner)
A very low pressure leads to cavitation (signalled by its peculiar noise): the pump manifacturer declares the minimum value. Therefore,
check the pump technical sheets. By increasing the oil temperature, also the minimum inlet pressure at the pump must increase, to
avoid the gassification of the oil low-boiling products and the cavitation. The cavitation compromises the burner operation, it causes the
pump to break too. The diagram on Fig. 7 roughly shows the inlet pump pressure according to the oil temperature.
Pump operating maximum pressure (both for the supplying system and burner)
Remember that pumps and all the system components through which the oil circulates, feature an upper limit. Always read the techni-
cal documentation for each component. Schemes on and are taken from UNI 9248 "liquid fuel feeding lines from tank to burner" stan-
dard and show how a feeding line should be designed. For other countries, see related laws in force. The pipe dimensioning, the
execution and the winding dimensioning and other construcitve details must be provided by the installer.
Adjusting the supplying oil ring
According to the heavy oil viscosity used, in the table below indicative temperature and pressure values to be set are shown.
Note:
the temperature and pressure range allowed by the supplying ring components must be checked in the specifications table of the
components themselves.
Tab. 1
HEAVY OIL VISCOSITY AT 50 °C
PIPELINE
PRESSURE
PIPELINE
TEMPERATURE
cSt (°E)
bar
°C
< 50 (7)
1- 2
20
> 50 (7)
< 110 (15)
1- 2
50
> 110 (15)
< 400 (50)
1- 2
65
