How much butane for little 7 inch tube?

I recently bought a BHO extractor tube its a little one designed for a quarter oz at most its about 7 inches long and about my pinky finger inside. using close trim and I have 3oz cans of butane, how many cans should I use? I think its most likley between one and two of these little 3oz cans

Spray until the tane coming out is clear. Generally 1 300mL can per ounce.

Yeah, you do it until it comes out clear. One can should last about 2-3 tubes worth.

i do a little over a can for an oz of good... empty a can then spray for 10 seconds on a new one