ISEN-ASTC-L is a service of the Association of Science-Technology Centers Incorporated, a worldwide network of science museums and related institutions. ***************************************************************************** Does it need to be drained by gravity? Can you just connect a little peristaltic or small inline circulator pump to force it to drain at the desired rate? If it needs to be gravity drained, then you will have to figure out how fast the water naturally drains at the lowest level. Then find a valve that will keep it draining at that rate at higher water levels. With gravity drains, you can always find something to decrease the flow of water, but not something to increase it. So if you can use a pump, it might be the easiest option. Regards. Michael Ross Program Educator Connecticut Science Center 250 Columbus Boulevard Hartford, CT 06103 Direct: 860.520.2104 www.CTScienceCenter.org | (860) SCIENCE ************************************* OCT 16 - Annual Gala Goes Green - INFO Follow us on ************************************* -----Original Message----- From: Informal Science Education Network [mailto:[log in to unmask]] On Behalf Of Peter Ford Sent: Thursday, August 19, 2010 11:08 AM To: [log in to unmask] Subject: How to drain a tank of water at a constant rate? ISEN-ASTC-L is a service of the Association of Science-Technology Centers Incorporated, a worldwide network of science museums and related institutions. ***************************************************************************** Hi all, Here's the technical dilemma that I'm trying to solve. I want to drain a tank of water, from the bottom, at the same rate regardless of how much water is in the tank. So whether there is 5" or 20" of water in the tank it will drain at ˝ gal a minute (values are somewhat arbitrary for this example). So how can I do this? I've tested Pressure-Compensating Orifice from McMaster but that didn't work (I think the pressure is to low for them to work). I have seen devices that automatically regulate but they are for larger industrial systems (and cost a lot), or they are for higher pressure systems. For more specificity it's a 11" diameter tank and I'm draining through a 1" valve. The water height varies between 4" to 30" Any solutions, or ideas, would be appreciated. Thank you in advance. -Peter *********************************************************************** For information about the Association of Science-Technology Centers and the Informal Science Education Network please visit www.astc.org. Check out the latest case studies and reviews on ExhibitFiles at www.exhibitfiles.org. The ISEN-ASTC-L email list is powered by LISTSERVR software from L-Soft. To learn more, visit http://www.lsoft.com/LISTSERV-powered.html. To remove your e-mail address from the ISEN-ASTC-L list, send the message SIGNOFF ISEN-ASTC-L in the BODY of a message to [log in to unmask] *********************************************************************** For information about the Association of Science-Technology Centers and the Informal Science Education Network please visit www.astc.org. Check out the latest case studies and reviews on ExhibitFiles at www.exhibitfiles.org. The ISEN-ASTC-L email list is powered by LISTSERVR software from L-Soft. To learn more, visit http://www.lsoft.com/LISTSERV-powered.html. To remove your e-mail address from the ISEN-ASTC-L list, send the message SIGNOFF ISEN-ASTC-L in the BODY of a message to [log in to unmask]