Cv
Cv turns up in 2 fields: valves, nonwovens. Here is what it means to the people in each one.
Cv in valves
Flow coefficient: US gallons per minute of 60 degree F water a valve passes with a 1 psi pressure drop.
Flow coefficient. Liquid flow scales as Q = Cv times the square root of pressure drop divided by specific gravity, so a valve with Cv 100 passes about 100 gpm of water at 1 psi drop and 200 gpm at 4 psi. Rated Cv is the full-open value, while control valves are sized so the required Cv falls around 20 to 80 percent travel. The metric equivalent is Kv, cubic meters per hour at 1 bar, and Cv is about 1.16 times Kv.
"Required Cv at max flow is 38, the 2 inch valve has 46 full open, so it's tight but it'll work."
CV in nonwovens
Coefficient of variation: standard deviation divided by the mean, the yardstick of nonwoven uniformity.
Short for coefficient of variation, expressed as a percentage. On the line it most often means basis weight variation, measured by an online scanner or by cutting and weighing a grid of samples. A low CV means even coverage, which matters for barrier, opacity and print, and many buyers put a CV limit in the spec next to the average weight.
"Weight CV jumped to 6 percent after the die cleaning, something is off in the air profile."