User Guide

15
Figure 14 How temperature affects viscosity.
Although such situations are not widespread, it is good to know
how to diagnose the problem and find a solution for it. While
some success has been reported with special nozzles, most service
technicians have found that the surest solution is to increase the
energy input. This is done by increasing pump pressure from 100
psi to 120-125 psi. And since increased pressure means increased
flow rate, it may be desirable to use the next size smaller nozzle.
As the burner ignites, it acts as an oil pre-heater and the viscosity
problem will disappear in 10 to 15 minutes. The burner can be left
at this increased pressure without harm to the pump. In extreme
cases of high viscosity due to cold oil it may be necessary to pre-
heat the oil to get ignition.
Figure 15 Cold Oil
Figure 16 High viscosity spray
Temperature
Viscosity
Temperature F 100 80 30 20
Viscosity (SSU) 35 37 52 65