These are replacement oil metering valves for stoves and heaters.
These valves are available factory calibrated for 3 fuel oil viscosities:
• # 2 Diesel (Stamped D on the side)
• # 1 Diesel (Stove Oil) (Stamped SO on the side)
• Kerosene (Stamped K on the side)
Being the most common diesel fuel, oil metering valves installed in stoves and heaters are calibrated for #2 diesel, unless otherwise requested.
Burning #1 diesel (stove oil) will allow 25% more fuel, and burning kerosene will allow 50% more fuel, to flow through a "D" calibrated oil-metering valve.
Because of this, it is important to burn the fuel for which the heater has been calibrated.
However, you can re-calibrate your valve to be optimized for each type of fuel, should you decide to burn a different fuel at some point.
Diesel is one of the few fuels you can reliably get all around the world, but the quality and viscosity of that fuel is
Fuel differs on a routine basis even though you buy the same oil from the same supplier.
Factors influencing oil viscosity include: the temperature; the age and quality of the fuel; the regional differences due to
local refineries; and the particular mix of certain brands of fuel.
To account for this variability in viscosity (flow rate through the valve) within a type of fuel, you can adjust the way you operate the stove.
If the oil is thicker than usual, open the valve more or use less of the fan.
If the fuel is thin, run the fan more to burn off the fuel to keep a clean burn.
While it is convenient to burn #2 diesel in your stove, since you are probably already carrying iy for your engine, # 1 diesel or kerosene are cleaner burniing fuels.
Bio-Diesel: Note that due to the higher vaporization temperatures of biodiesel and the variability in composition and blends along with viscosity differences, the flow rate setting on the valve will need to be adjusted for each batch of fuel.