Bulk Modulus of brake fluid

[jack]

does anyone have any numbers for this? how does 200,000psi sound for a general guess?

does anyone know what it is, or where i could find it for DOT 3 and DOT 5? thanks.

[jack]

does anyone have any numbers for this? how does 200,000psi sound for a general guess?

does anyone know what it is, or where i could find it for DOT 3 and DOT 5? thanks.

[Denny Trimble]

β = 2.5 x 10^5 lbf/in^2

Used in a lecture slide about hydraulic systems from MIT (PDF). (http://psdam.mit.edu/2.000/administrative/lectures/Hydraulics%20I.pdf)

I couldn't find anything other than that, without access to SAE standards.

[MikeWaggoner at UW]

DOT 5 is silicone, so it's lower than normal brake fluid. I'd recommend not using it, given the amount of time these cars spend apart (and get bled) there ain't much advantage.

There's a book called Hydraulic Fluids that your library may have. Common fluids don't change by an order of magnitude:

Bulk Modulus for some common fluids can be found in the table below:
Bulk Modulus - Ev Imperial Units - BG
(psi, lbf/in2) x 105 SI Units
(Pa, N/m2) x 109
Carbon Tetrachloride 1.91 1.31
Ethyl Alcohol 1.54 1.06
Gasoline 1.9 1.3
Glycerin 6.56 4.52
Mercury 4.14 2.85
SAE 30 Oil 2.2 1.5
Seawater 3.39 2.35
Water 3.12 2.15

[jack]

thanks. yeah, i just wanted to comapair DOT 3 to DOT 5 for the hell of it. we will use DOT 3 as usual.