1 For surface waters, between 20 and 40 mm (upstream the strainer)  For municipal wastewater: for raw water, from 15 to 30 mm (but upstream from a straining and/ or lamellae settling process, fine screening is necessary); for sludge (if necessary), 10 mm or less.
Other studies. According to some studies, 18-year-old males have a refractory period of about 15 minutes, while those in their 70s take about 20 hours, with the average for all men being about a half-hour. Although rarer, some males exhibit no refractory period or a refractory period lasting less than 10 seconds.
E. Answer : The length of your cycle is the interval in days between the first day of flow of one period and the first day of flow of the next period. The normal menstrual cycle ranges from 25 to 35 days, with a 28-day average. The menstrual flow itself (abbreviated AF on many internet chat groups) can last two to seven days, with an average of four days. We arbitrarily consider the first day of menstrual bleeding as Day 1 of your cycle.