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.
That is the absolute refractory period. Once they start resetting, you have the relative refractory period, where you can stimulate another action potential, but you will need a stronger stimulus. So thatâs the absolute and the relative refractory periods. I hope it makes sense. Thatâs all for this video, and Iâll see you in the next one.