wyaple
Well-known member
The first two measurements were easy to get, the last one (CFM at the nozzle) required me to build an airflow box. I think this pic should easily illustrate where and by how much CFM is lost in this machine. I think this is typical performance from this 19 year old cleaner.
From the base of the machine to the hose (stretched out straight), there is a loss of 87-65 = 22 CFM. From the hose to the nozzle, there is a loss of 65-33 = 32 CFM. The CFM lost through the pivot arm and housing assembly (in the power nozzle) is the largest I've measured so far. Even with like new performing parts, you can easily hear air escaping when holding the power nozzle grip at certain angles.
Total airflow losses from the canister base to the power nozzle (held at a 45 degree angle to the floor) is 87-33 = 54 CFM or about 62% of the original airflow. Of course the Rainbow claim to fame is no decrease in airflow and I can say that measurements confirm that no matter if the basin has dirt or even water in it, the airflow stays very constant.
Last note: the rug plate opening is small (about 20 square inches) and the CFM density is well below average, about 1.6 CFM/Sq. In. With a CFM density that low, it would be difficult to get much deep down dirt if it weren't for the very aggressive brush roll with leading edge beater bars built in.
I would personally love to see a Rainbow that has something around 70-80 CFM at the power nozzle but that may mean the canister airflow might have to be in the 120 CFM range. Here's hoping...
Bill
From the base of the machine to the hose (stretched out straight), there is a loss of 87-65 = 22 CFM. From the hose to the nozzle, there is a loss of 65-33 = 32 CFM. The CFM lost through the pivot arm and housing assembly (in the power nozzle) is the largest I've measured so far. Even with like new performing parts, you can easily hear air escaping when holding the power nozzle grip at certain angles.
Total airflow losses from the canister base to the power nozzle (held at a 45 degree angle to the floor) is 87-33 = 54 CFM or about 62% of the original airflow. Of course the Rainbow claim to fame is no decrease in airflow and I can say that measurements confirm that no matter if the basin has dirt or even water in it, the airflow stays very constant.
Last note: the rug plate opening is small (about 20 square inches) and the CFM density is well below average, about 1.6 CFM/Sq. In. With a CFM density that low, it would be difficult to get much deep down dirt if it weren't for the very aggressive brush roll with leading edge beater bars built in.
I would personally love to see a Rainbow that has something around 70-80 CFM at the power nozzle but that may mean the canister airflow might have to be in the 120 CFM range. Here's hoping...
Bill
