Central Vac - working vacuum pressure

[panofan]

So I did a test with my central vac.
I put a suction meter against one of the inlets and then plugged my hose & powerhead into another outlet -- the idea being this would tell me the working pressure in the system (instead of the fully sealed).

My central vac has the Ametek 116119 motor ( http://dev.ametekfsm.com/Bulletins/116119-00.pdf )

I have a centec electric kit & an MD TT27 air only kit. The air only kit's hose definately seems larger / smoother inside (despite both kits being relatively new)

So I found:
Electric Hose only:
working pressure ~ 42 inches of water lift
with power head attached -- no noticeable change

MD Air only hose (hose only):
working pressure ~ 30 inches of water lift
with the TT27 attach -- ~45 inches of water lift.

Here is my interpretation:
Restrictions in the system are equivalent to a smaller orifice - which means more vacuum pressure and less airflow.

So, the MD hose really is smoother than the electric hose.
Adding the turbo brush restricts airflow / adds friction (makes sense - it is turning the turbine and has a smaller opening).
But, it looks like the energy lost in the electric hose is almost equal the the energy lost to power the turbo brush.
I'm taking this to mean there is actually more air flow into the turbo brush since it is about 11" wide instead of 15" (like the CT20DXQS), and not as deep - lower area of the brush opening --> implies more air flow per area.

Has anyone else done a similar test?

 

[sanitaire]

sounds like fun. would be fun too test residental hose vs commercial hose. most of my hose is commercial and it's smoother on the insides and get good airflow. even at 12'. most is inch and half diameter... it also helps too have vac like the nss pic creating the suction. I've rigged up my central vac hose on it and puts too much restriction on the motor.....