Pound per square inch compared to pound per linear inch

[Transient1]

Hi,

I need to compare pound per linear inch to pound per square inch. I am right to figure that if it is 10 pounds per linear inch, that then it would be 100 pounds per square inch?

 

[COEngineeer]

It depends on the span.

 

[structuralaggie]

You'll need to give a little better information. I can't make sense of what you are asking or how you got 100 from 10.

 

[Transient1]

All right, I have an aluminum spacer ring that has a cross section of .21 in. by .093 in. tall. It is fastened down so that there is a holding force of 60 psi. There is a gasket whose spec is roughly that it requires 20 pounds per linear inch to deform to the point of metal to metal contact. I need to be able to compute pounds per linear inch.

 

[structuralaggie]

Ok, I guess I shouldn't have asked. A width in inches times a pressure in psi would give you pli.

 

[Transient1]

Thanks.

 

[rb1957]

i know i'm pedantic, but a force is means in lbs and a pressure (a force acting over an area) is measured in psi.
If the gasket requires 20 lbs/in to deflect, how long is it ... that's the force required, call it 20L lbs.

if you have a pressure acting, i assume that the gasket make
s a closed loop ... enclosing an area, so if you have 60psi acting over an area, Ain2, then you have a force of 60A lbs.

 

[Transient1]

rb1957,

The spec is for pounds per linear inch, not pounds per inch. The force required is as structuralaggie has defined it (psi * width).

 

[whyun]

What is the difference between pounds per linear inch and pounds per inch?

It helps when you put the units as fraction instead of abbreviation.

 

[rb1957]

thx whyun, you beat me to it

 

[racookpe1978]

Makes sense (from the rubber fabricator's standpoint at least!) for him to specify pounds per linear inch of his gasket, because he doesn't know how big an o-ring (how far around/what dia) the o-ring is going to become.

So he specifies pounds per inch of (his) rubber. Then sells thousands of o-rings of various diameters, and as linear seals for rectangular lids and covers. The mechanical engineer then has to decide on what pressure he will put on the o-ring by deciding the number of bolts, torque, and length of the seal.

Warning: Welds are also specified by pounds per inch ... but that is how much force the weld (of some electrode, and some fillet height and width) can handle per inch length of the weld.