Sure scot, thank you! The '...below suggestion...' was laziness on my part. I should have said (from The Law Of Falling Bodies) t=(2h/g)^.5 - In words, double the height of the butt (in feet), divide by 32, the square root of that number is the Time Of Flight in seconds, divide the middle of the splash length by TOF and you get the velocity. Using two rocks, you calc a minimum and a maximum velocity to get the average (measure 2 lengths). The reason I said better yet 2 rocks is because, although I have always had a pitot to measure the velocity, I always look to see if I could locate the middle of the splash if I had to. From now on I will look for the start and the end of the splash. BTW your z = 1/2g*t^2 is where my t=(2h/g)^.5 comes from, if you replace z with h.
-----Original Message----- From: å... .... [mailto:[email protected]] Sent: Sunday, July 04, 2010 4:01 PM To: [email protected] Subject: Accuracy of Hydrant Flow Test Using Pitot Diffuser Perhaps it would be better to calculate the time that the drop falls--based on the measured height (z, in feet) from the middle of the bore, down to the ground. z = 1/2g*t^2 + Vz,o*t Vz,o=0 (vertical velocity at time, 0 seconds) t = sqrt (z)/4, for your example, this gives 1/2 second. Using the below suggestion, how do we solve for time when we haven't measured the vertical velocity at impact? The overall method is great, thank you for sharing, Brad. scot deal excelsior fire On Mon, Jun 28, 2010 at 7:04 PM, Brad <[email protected]> wrote: > You could, or you could calc the time based on velocity equals acceleration > times time. Instead of the comb you could look for a rock. Better yet 2 > rocks, as an old timer replied off forum, he measured from the start of the > splash to the end of the splash to get the average [sic] (distance " x " > from the butt ) velocity. _______________________________________________ Sprinklerforum mailing list [email protected] http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum For Technical Assistance, send an email to: [email protected] To Unsubscribe, send an email to:[email protected] (Put the word unsubscribe in the subject field) _______________________________________________ Sprinklerforum mailing list [email protected] http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum For Technical Assistance, send an email to: [email protected] To Unsubscribe, send an email to:[email protected] (Put the word unsubscribe in the subject field)
