when i take the head off and hold the pipe onto the palm of my hand it pulls on the skin of my palm, pulling it into the pipe. So there is certainly suction. Its just I dont know how to measure whether its the correct amount.
Interestingly when the vacuum pulls the hand entirely over the pipe so that no air can get it, the vacuum makes a sort of pulsing sound coming out of the main body. Almost like there is some sort of valve in there that is flipping open and closed when the vacuum cannot pull air through the pipe.