wyaple
Well-known member
I've seen a few paper towel and toilet roll tube testing videos on YouTube and have found some people put great faith in them. So I grabbed a Kirby G5 and G6 and got down to testing what the seemingly "magic" rolling tube can actually uncover.
Testing conditions:
1) Both machines, which normally have HEPA cloth bags, had the bags removed and outer bags zipped up. By the way, before anyone complains about that, my anemometer says that a fresh Kirby HEPA bag only restricts airflow a whopping 2 CFM. So no big deal.
2) Both machines were plugged into a power strip that was plugged directly into a dedicated 20 Amp (2400 Watt) outlet. This was done to ensure exactly the same voltage going to the test subjects. This is a very important step as varying voltages definitely affect the outcome.
3) Both machines had their brush rolls spinning and heights adjusted all the way up and were checked to be at the same height within about 1/32nd of an inch. If the heights were misadjusted (say 1 click), the results usually favored the lower machine.
4) Tests were performed a minimum of 20 times on both medium pile carpet and bare flooring (concrete).
5) The toilet roll tube was placed in three locations; the middle and both ends of the nozzles.
6) Both machines had the same brush roll (152502 oblique loose tufts) and belt installed and were of equal age (new). I realize that belts and brush rolls for this test shouldn't make any appreciable difference as they never touched any surface.
7) I knew beforehand that the G5 had 126 CFM and the G6 had 122 CFM as previously measured on my airflow box.
Medium Pile Carpet Results:
In every instance, the paper tube was either "stuck" or could be "re-stuck" to the G5's nozzle. The 4 CFM difference was readily apparent.
Bare Floor (Concrete) Results:
About 75% of the time, the G5 won, about 25% of the time, the G6 won.
CONCLUSION:
Since a paper tube is VERY light, it can detect VERY small differences in airflow, even becoming finicky on bare floors. The G5 and G6 only have a 4 CFM difference in airflow and that difference only amounts to a little over 3%, which is barely statistically significant. Hence, people claiming massive superiority by performing this type of test could easily be fooling themselves if they pair up two machines with very small airflow differences.
RECOMMENDATION:
Stick to real, measurable airflow/airbox measurements if you care about such things.
Further testing may be done if time permits pairing up my G4 and G6 because they differ only by 2 CFM instead of 4 CFM.
Bill
Testing conditions:
1) Both machines, which normally have HEPA cloth bags, had the bags removed and outer bags zipped up. By the way, before anyone complains about that, my anemometer says that a fresh Kirby HEPA bag only restricts airflow a whopping 2 CFM. So no big deal.
2) Both machines were plugged into a power strip that was plugged directly into a dedicated 20 Amp (2400 Watt) outlet. This was done to ensure exactly the same voltage going to the test subjects. This is a very important step as varying voltages definitely affect the outcome.
3) Both machines had their brush rolls spinning and heights adjusted all the way up and were checked to be at the same height within about 1/32nd of an inch. If the heights were misadjusted (say 1 click), the results usually favored the lower machine.
4) Tests were performed a minimum of 20 times on both medium pile carpet and bare flooring (concrete).
5) The toilet roll tube was placed in three locations; the middle and both ends of the nozzles.
6) Both machines had the same brush roll (152502 oblique loose tufts) and belt installed and were of equal age (new). I realize that belts and brush rolls for this test shouldn't make any appreciable difference as they never touched any surface.
7) I knew beforehand that the G5 had 126 CFM and the G6 had 122 CFM as previously measured on my airflow box.
Medium Pile Carpet Results:
In every instance, the paper tube was either "stuck" or could be "re-stuck" to the G5's nozzle. The 4 CFM difference was readily apparent.
Bare Floor (Concrete) Results:
About 75% of the time, the G5 won, about 25% of the time, the G6 won.
CONCLUSION:
Since a paper tube is VERY light, it can detect VERY small differences in airflow, even becoming finicky on bare floors. The G5 and G6 only have a 4 CFM difference in airflow and that difference only amounts to a little over 3%, which is barely statistically significant. Hence, people claiming massive superiority by performing this type of test could easily be fooling themselves if they pair up two machines with very small airflow differences.
RECOMMENDATION:
Stick to real, measurable airflow/airbox measurements if you care about such things.
Further testing may be done if time permits pairing up my G4 and G6 because they differ only by 2 CFM instead of 4 CFM.
Bill
