Suction Ratings
Dave,
What I have found in regards to suction ratings, today you'll get a reading, tomorrow it could be different. I have found that it depends on the altitude, (lower elevation produce more inches of lift) the barometric pressure, and how many volts are coming through the line.
Have you thought of buying a Baird airflow meter to measure airflow?? I've got one and it's quite interesting to see which machine has more than the other.
Vernon