Air valves with ball floats
Most of the original automatic air valves were based on having hollow balls as the most common choice for the floats. This was because their high buoyancy ensured they could easily create a seal when the water was displaced by air in the valve. Although the theory is sound, the original designs had flaws:
- In order to make the valves of commercially viable size, the orifices all had large reductions in size from the nominal inlet bore.
- Some designers who wanted to increase the capacity had large orifices, but often found that the ratio between orifice and ball diameter was too big, and the ball floats would jam.
- Seal designs were often inferior, and caused the high force between float and seal to “weld” the ball to the seal. The result was that the balls would not release during vacuum conditions and would caused pipe collapse.
- Due to above constraints the valves were large in size and commercially expensive.
A South African inventor came on the market and developed a novel new idea: a “barrel” body and floats of HDPE. This made the valve very compact, with features that were quickly adopted by the market.
Like any new product, it had its flaws such as “drowning” floats during pipe filling, and breaking the air valve from water hammer damage due to the full bore orifice allowing too high a flow rate. Modifications to resolve these problems resulted in the specifications of a full bore orifice, and non-slam secondary orifice, cleverly marketed as water-hammer-preventing air valves. The SA engineering fraternity accepted these specs as gospel, and even today the valve is specified all over the country.
When A.R.I. entered the market in the 1990s, it found the industry “brainwashed” by these specs, and realised that a new design was needed which would better meet these criteria. The new model incorporated a non-slam device that could be easily removed as an external part, as A.R.I. realised that it was not a workable solution in 80% of applications. This gave engineers the choice to either have it, or not.
The SA design manufacturers went on an aggressive marketing campaign to rid the market of “air valves with ball floats”, despite A.R.I. having designed out all the old problems with ball floats, and developed what is now the best air valve in the world, incorporating unprecedented features.
The author reminds the market of these features which are summarized in the last 3 pages of the A.R.I. Catalogue and seen on our website www.ultravalves.co.za in the newsletter section.