PTS Flowbench Forum

Hello to all - first post here and have to say I am really impressed with the collection of minds and comradery here. Bruce you'll be gaining a new customer soon !

My question. If I doubled the specific gravity of the fluid used in the manometers would the fluid movement be halved?

The reason I ask is, if I wanted to build a bench with the capability of high depression like 120 inches could I use a different density fluid then get away by using a shorter manometer, something 60 inches long.

Thanks in advance
Warren

Short answer, yes.
Have a look at the spreadsheet in THIS THREAD, for the manometer calculations, one of the input parameters is fluid specific gravity.

AT ONE TIME WE USED TO USE MERCURY TO SYNC THE CARBS ON MOTORCYCLES, NOW IT IS A BIG NO-NO TO DO ANYTHING WITH MERCURY. ALL THE NEW MANOMETERS TO SYNC MOTORCYCLE CARBS USE BASICALLY ANTIFREEZE, IT IS A GLYCOL BASED FLUID. MAYBE IT WOULD WORK FOR YOU? SOUNDS LIKE YOU NEED SOMETHING HEAVIER LIKE A LIGHT WEIGHT OIL.

There are high density manometer fluids available, Dwyer has a 1.90sg fluid as does Meriam, Meriam also has a 2.95 fluid, unfortunately they're rather expensive and the 2.95 fluid is highly corrosive to metals, nasty stuff.

Thanks y'all for the advice
Rocco - you gave me more than enough ammo to work with Thanks. I never realized there were so many options available.

Beetle -I was almost leaning towards Mercury because the math conversions would be fairly simple then you mentioned something about light weight motor oil, I also came up with that idea until I started thinking,,,,, doesn't oil float on water? So the newbie question of the night is what makes a good manometer fluid?
Isn't Specific gravity and density of a fluid basically the same thing or am I way off?
Viscosity has to be a factor in there somewhere too especially with different diameter manometer tubes.
I know I'm asking a lot of questions but I like thinking outside the box especially with all the knowledge available here.
Thanks again in advance
Warren

I'm asking these newbie questions because when building my bench I am going to go all digital, but just wanted to have a manual manometer as a back up reference.
I know it makes things a bit more complicated but I'm just anal about catching an obvious mistake before it goes out the door.

Finding a safe heavier specific gravity liquid may be tough. Here is a list that I found:
http://www.engineeringtoolbox.com/speci ... d_336.html

Chloroform looks interesting if you can stay awake while flowing.

John

Here is another one and iodine in 4.9 spg

http://www.simetric.co.uk/si_liquids.htm

Bromine is also heavy but looks to be some nasty stuff also.

If you are looking to do 120" H2O you could try a "U" tube verticle manometer 60" or a little longer. With a "U" tube manometer you would have 60" up on one leg and 60" down on the other to equal 120" H2O and be able to use water as your fluid. That is the way I would probably go.

John

jfholm wrote: If you are looking to do 120" H2O you could try a "U" tube verticle manometer 60" or a little longer. With a "U" tube manometer you would have 60" up on one leg and 60" down on the other to equal 120" H2O and be able to use water as your fluid. That is the way I would probably go.

John

You need a room with at least 120" of height and a step ladder to read it

Don't wanna know how I know that one . . . one of those what were you thinking days

Yep, I get those what was I thinking days more and more lately -

Here's a why am I thinking moment, instead of a straight manometer tube/scale what would happen if , say you made a manometer by accurately wrapping the tubing around a 2 or 3 inch dowel/cardboard tube to an over all length of 48 inches? As the fluid spirals upward to a verticle height of lets say 28 inches the fluid has probably traveled (guessing here) closer to 60 inches. What would my depression be , 28 or 60 inches of water?
Any thoughts here guys as my wife is forbidding me to go back out to the garage tonight and experiment.

Warren