Gasket Compression Design

[engineeringcontractor]

Hi, just wanted to double check I was using the formula on this page correctly as I'm using it in a slightly different capacity;

http://www.engineersedge.com/general...ompression.htm

I'm actually designing a new product that's basically a polycarbonate case with a lid, the gasket between the two needs to provide IP65 and IP67 protection.

Therefore first question, since the formula used is designed for high pressure pipe lines and such, can I disregard the Pmax and Pmin figures as my case will not be pressurised, and therefore just see atmospheric pressure on both sides of the seal? So actually the whole formula will just be divided by 13+2.

Also, I take it values for H1 and H2 will be gathered from the gasket supplier? As in H1 will be 25% compression (A good typical o-ring compression value) up the maximum that's recommended for that gasket I.e. Around 40%?

So I've got; (All in mm btw)

C = ((480*(1/.25)*2600*4^3*.4)/(15))^.25

Cheers

[Kelly_Bramble]

You should also see the following video:

What is the Right Flatness Tolerance for a Gasket Application

[Kelly_Bramble]

FYI - the equation specified on the webpage for Delta-H was incorrect. It should be H2 - H1.. It has since been corrected.

Hi, just wanted to double check I was using the formula on this page correctly as I'm using it in a slightly different capacity;

http://www.engineersedge.com/general_engineering/gasket_cover_compression.htm

I'm actually designing a new product that's basically a polycarbonate case with a lid, the gasket between the two needs to provide IP65 and IP67 protection.

Therefore first question, since the formula used is designed for high pressure pipe lines and such, can I disregard the Pmax and Pmin figures as my case will not be pressurised, and therefore just see atmospheric pressure on both sides of the seal? So actually the whole formula will just be divided by 13+2.

Also, I take it values for H1 and H2 will be gathered from the gasket supplier? As in H1 will be 25% compression (A good typical o-ring compression value) up the maximum that's recommended for that gasket I.e. Around 40%?

So I've got; (All in mm btw)

C = ((480*(1/.25)*2600*4^3*.4)/(15))^.25

Cheers

[eckotapish]

Hi,
Just to enlighten anybody that is curious. The equation for fastener spacing of gaskets starts with assuming a parabolic pressure intensity between the fasteners where x=0 and x=C is Pmax, x=C/2 is Pmin.

Adding up (Pmax-Pmin)*C/3 for the parabolic part and Pmin*C gives (Pmax+2*Pmin)*C/3 for the force per unit width. Force on the gasket is (Pmax+2*Pmin)*C*b/3. The equation also assumes I=a*t^3/12 that is substituted into deltah=[(13*Pmin+2*Pmax)*C^4*b]/(5760*E*I) to get deltah=[(13*Pmin+2*Pmax)*C^4*b]/(480*E*a*t^3).

Ta da!

Ed

[Kelly_Bramble]

Nice...

Hi,
Just to enlighten anybody that is curious. The equation for fastener spacing of gaskets starts with assuming a parabolic pressure intensity between the fasteners where x=0 and x=C is Pmax, x=C/2 is Pmin.

Adding up (Pmax-Pmin)*C/3 for the parabolic part and Pmin*C gives (Pmax+2*Pmin)*C/3 for the force per unit width. Force on the gasket is (Pmax+2*Pmin)*C*b/3. The equation also assumes I=a*t^3/12 that is substituted into deltah=[(13*Pmin+2*Pmax)*C^4*b]/(5760*E*I) to get deltah=[(13*Pmin+2*Pmax)*C^4*b]/(480*E*a*t^3).

Ta da!

Ed