December 14, 1999
Some General observations:
If at all possible we should try for solutions that will not require constant policing, training and inspection. Such efforts are costly, time consuming and inevitably lead to oversights with resultant failures.
Design and modifications should be such that there is no possible danger to inspect for.
The more I think about this matter the more a limited gravity only system could make sense.
Such a system must have its hydraulic relationships fixed, or "cast in concrete" so to speak to insure an absolute limit to the gravity pull available.
I feel that in any design - new or retrofit that, it should be impossible to ever apply any direct pump suction to a swimming pool/spa suction outlet. Pools can be operated quite normally this way. We have around 200 such installations.
Study the simplistic sketch below and you can easily see what I am saying.
How as an industry we can get from here to there is the challenge.
I have one approach to this philosophy. I am certain there are and will be others.