Fluid Mechanics for Liquids

Temperature Rise in Hydraulic Fluids

Hydraulic fluid heats when flowing through a restriction as the pressure energy upstream of the restriction is converted into thermal energy.

\[\Delta\ \text{T}=\frac{0.003(\Delta\ \text{P})\ }{(S)(c)}\]

Where:

∆T = Temp. rise (°F)

∆P = Pressure drop (psi)

S = Specific gravity

c = Specific heat at 100 °F (BTU/LB_m°F)

Example

If a Lee Jet^{^®} is flowing MIL-H-83282 at 120°F and 2500 psid, the temperature rise across the Lee Jet is computed as follows:

For MIL-H-83282 at 120°F, S = 0.82, c = 0,50

\[\Delta\ \text{T}=\frac{(0.003)(2500)\ }{(0.82)(0.50)}=18.3^{\circ}\ \text{F}\]

This example is displayed on the nomogram below.

Instructions to use nomogram