by 84-1074663779 » Fri Feb 04, 2005 5:58 pm
I agree, mercury has absolutely nothing going for it for a flowbench application.
Water is almost ideal, but commercial manometer oil is always going to be the best fluid available. The only real disadvantage of water is that it evaporates slowly, can freeze, and bugs and bacteria can grow in it.
I use distilled water with a tiny trace of bleach, a tiny trace of detergent, and a bit of green food colouring dye. The bleach kills the bugs, and the detergent reduces surface tension so the water does not stick so well to the inside of the manometer tube through capillary action.