Quote:
|
Originally Posted by BadNick
get ready for some relativity 
the relative size of the elastomer washer in the spigot changes with temperature; as the hot water heats the washer, it expands, pinches off the flow slightly which increases the water velocity which increases the pitch. Next time see if you can measure a slight reduction in water flow as the pitch increases and report back here. |
BINGO... That is exactly what happens..well done
in some cases the shaft of the valve expands too.
For an Iron or even a brass(close enough) shaft the expansion rate is .0000063 per inch of shaft per degree rise in temperature from the norm.
So for a valve with a 1.75 inch long shaft (purty normal length) it will expand
.0017 inches. That is almost two thousandths of an inch (towards closed)