×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Foot of head.

Foot of head.

Foot of head.

(OP)
I have heard a "Foot of head" described as the amount of pressure that a one foot high column of water exerts.  This defenition however fails to mention the diameter of this column.  Is there something that I am missing here?  Shouldn't the column of water have a specific volume?
Replies continue below

Recommended for you

RE: Foot of head.

No

"Head" as you have termed it is a measure of pressure and will therefore be independent of the volume. Remember using a U-tube manometer in the school physics lessons?  If you raise the level of the reservoir by a foot, the water travels a foot up the tube, regardless of the diameter of the tube (and provided your reservoir holds sufficient water).

Andy Machon

 
 

RE: Foot of head.

Afoot of head is about .4333333333333pounds per square inch

RE: Foot of head.

Adding to the above...

I think the thing that you failed to see was the difference between PRESSURE and FORCE.  A big column will have a bigger FORCE at the bottom, but it is also distributed over a bigger area.  Hence, the pressure will be the same no matter what the diameter is--for the same fluid, anyway.

RE: Foot of head.

The term 'head' is used to indicate the pressure exerted by the fluid. Pressure by definition is the force per unit area. The force exerted by the column of liquid say, water is the weight of the liquid column, which is given by

Area of cross section  x  height of the liquid column  x  specific weight of the liquid.

Therefore pressure is given by

Force/area = height of the liquid column  x  specific weight of the liquid.

Since, the specific weight of the liquid is a constant (of course at a given temperature), the pressure is expressed as so many'feet' of the liquid column. Hence, It is also important that the 'head' should always be associated with the fluid of reference, such as, 10 m. of water or 76 cm. of mercury etc. The pressure is obtained by multiplying the head by the specific weight of the fluid.

Trilinga

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login



News


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close