The CRP-1 can be used to quickly convert between different fuel units:
You have 80 litres of fuel on board. What is this in US Gallons and Imperial Gallons?
1 Line the quantity (80) up with the litres mark
2 Find the US Gal mark and read off the quantity from the inner scale
In this case, it is 21
So 80 litres is equal to 21 US Gallons
3 Find the Imp. Gal mark and read off the quantity from the inner scale
In this case, it is 17.5
So 80 litres is equal to 17.5 Imperial Gallons
Using the same example, we know we have 80 litres of AVGAS which is equal to 21 US Gallons or 17.5 Imperial Gallons. What does this amount of AVGAS weigh in both kilograms and pounds?
1 Line the quantity (80) up with the volume (litres) mark
2 Find the correct specific gravity (usually 0.72 for AVGAS) along the SP.G (specific gravity) scale. You can now read off the weight of the AVGAS in kilograms on the inner scale
So using 0.72 on the SP.G scale, we can see that 80 litres of fuel will weigh 57 kilograms (approx.)
3 To convert this 57kg into pounds, align 57 on the inner scale with the KG mark. Then find the lb mark and read off the weight in pounds from the inner scale.
Here we can see that 57 kg is equal to 125 lbs