Joshua refering to wikipaedia: "The quality of steam can be quantitatively
described by steam quality (steam dryness), the proportion of saturated
steam in a saturated water/steam mixture. [4] i.e., a steam quality of 0
indicates 100% water while a steam quality of 1 (or 100%) indicates 100%
steam."
This says that steam quality is referring to _saturated_ steam/water
mixture. This _saturated_ mixture however cannot exist in arbitrary
proportions in normal pressure and in closed container, but it is always
ca. 99-98%. (>95% to be in safe side). This is because surface tension and
pressure gredients in liquid.
However it has been documented up to 5-10% quality steam when they have
tested steam quality measuring instruments. Steam quality can be measured
e.g. by measuring the speed of sound in saturated steam/water mixture,
because it correlates with steam quality. And ultra low quality steam can
be produced e.g. by cooling rapidly high pressure/temperature/velocity
steam by spraying atomized water into it. (I think that even atomized water
is not low quality steam, because it does not form saturated steam/water
mixture)
It is good also to understand what is written and to pay attention to small
words such as "saturated". Technically speaking liquid water is not 0%
quality steam, because Liquid water should behave like superfluid in order
to be called as 0% quality steam.
—Jouni
