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From: James T. White on 10 Jul 2006 13:35 "joseph2k" <cooltechblue(a)yahoo.com> wrote in message news:5Zjsg.63428$fb2.619(a)newssvr27.news.prodigy.net > > Er, no. Continuous purge air would give erroneous readings. Purge, > stop, wait a little, then measure. Using aerator air for purge > trades a pump for a bit of tubing, purge valve is still required > though, potentially a good deal. Not if the purge valve is set so that the air flow is low enough. Then you can neglect the air friction just like you neglect the density of the air column. -- James T. White
From: Joerg on 10 Jul 2006 14:38 Hello James, >> >>Oh, I do that all the time. Thing is, the low pressure ones you mentioned >>look a bit flimsy. I'd prefer something that can be plumbed in. > > Matbe I'll have to put thim in some sort of enclosure with pipe threads > and pot them. > Check the irrigation section at Home Depot. Usually just across the main aisle from where the timers are. You might, for example, use 1/2" nipples and then end caps to glue the sensor into via a precisely dilled hole. No idea whether the sensors are also PVC. If not it might not work. Then a larger end cap over the other could be used to protect the contact joints. Or just use one end cap, drill a hole for the wires and epoxy the sensor into the bottom of it. But then you'd need another kind of nipple and an end cap that has the thread on its outside. In the end the whole thing would be screwed into the drums just like the water intake on many modern low-flow toilet tanks. A direct glue into the drum might be dicey because they can flex a bit. > > I'll have to look the next time I'm in the one up the road. I was > there today but I didn't have those on my list. I'll start a new list. > Look for the term "rain sensor" on the package. Or take the timer out of the box and see if it has a rain sensor terminal pair. The sensor itself is probably going to be special order unless you live in an area that gets a good dose of thunderstorms in summer. -- Regards, Joerg http://www.analogconsultants.com
From: joseph2k on 14 Jul 2006 07:56 James T. White wrote: > "joseph2k" <cooltechblue(a)yahoo.com> wrote in message > news:5Zjsg.63428$fb2.619(a)newssvr27.news.prodigy.net >> >> Er, no. Continuous purge air would give erroneous readings. Purge, >> stop, wait a little, then measure. Using aerator air for purge >> trades a pump for a bit of tubing, purge valve is still required >> though, potentially a good deal. > > Not if the purge valve is set so that the air flow is low enough. Then > you can neglect the air friction just like you neglect the density of > the air column. > Then you run the risk of never achieving purge, and not knowing it. -- JosephKK Gegen dummheit kampfen die Gotter Selbst, vergebens. --Schiller
From: James F. Mayer on 16 Jul 2006 21:33
"joseph2k" <cooltechblue(a)yahoo.com> wrote in message news:uDLtg.65547$fb2.33528(a)newssvr27.news.prodigy.net... > James T. White wrote: > >> "joseph2k" <cooltechblue(a)yahoo.com> wrote in message >> news:5Zjsg.63428$fb2.619(a)newssvr27.news.prodigy.net >>> >>> Er, no. Continuous purge air would give erroneous readings. Purge, >>> stop, wait a little, then measure. Using aerator air for purge >>> trades a pump for a bit of tubing, purge valve is still required >>> though, potentially a good deal. >> >> Not if the purge valve is set so that the air flow is low enough. Then >> you can neglect the air friction just like you neglect the density of >> the air column. >> > Then you run the risk of never achieving purge, and not knowing it. One bubble every minute or so should be sufficient to provide the proper purge. |