Manual

AOC
AIR COOLED AOC
www.thermaltransfer.com [e-mail] 262.554.8330
27
C
V
Viscosity Correction
OIL
SAE 5 SAE 10 SAE 20 SAE 30 SAE 40
Average 110 SSU at 100°F 150 SSU at 100°F 275 SSU at 100°F 500 SSU at 100°F 750 SSU at 100°F
Oil Temp °F 40 SSU at 210°F 43 SSU at 210°F 50 SSU at 210°F 65 SSU at 210°F 75 SSU at 210°F
100 1.14 1.22 1.35 1.58 1.77
150 1.01 1.05 1.11 1.21 1.31
200 .99 1.00 1.01 1.08 1.10
250 .95 .98 .99 1.00 1.00
Selection Procedure
Performance Curves are based on 50SSU oil entering the cooler 50°F higher
than the ambient air temperature used for cooling. This is also referred to as
a 50°F Entering Temperature Difference (ETD).
STEP 1 Determine the Heat Load.This will vary with different systems,
but typically coolers are sized to remove 25 to 50% of the input
nameplate horsepower.
(Example: 100 HP Power Unit x .33 = 33 HP Heat load.)
To convert HP to BTU/Hr: HP x 2545 = BTU/Hr
STEP 2 Entering Temperature Difference. Desired oil entering cooler
°F – Ambient air temp. °F = Actual ETD
STEP 3 Determine Curve BTU/Hr Heat Load. Enter the information
from above:
BTU/Hr heat load x
50 x Cv
= Curve BTU/Hr
ETD
STEP 4 Enter curves at oil flow through cooler and curve horsepower.
Any curve above the intersecting point will work.
STEP 5 Determine Oil Pressure Drop from Curves:
l = 5 PSI; n = 10 PSI; s = 20 PSI. Multiply pressure drop from
curve by correction factor found in oil
P correction curve.
Desired Reservoir Temperature
Return Line Cooling: Desired temperature is the oil temperature leaving the
cooler. This will be the same temperature that will be found in the reservoir.
Off-Line Recirculation Cooling Loop: Desired temperature is the oil
temperature entering the cooler. In this case, the oil temperature change
must be determined so that the actual oil leaving temperature can be found.
Calculate the oil temperature change (oil
T) with this formula:
Oil
T = (BTU’s/Hr.) / (GPM Oil Flow x 210).
To calculate the oil leaving temperature from the cooler, use this formula:
Oil Leaving Temp. = Oil Entering Temp – Oil
T.
This formula may also be used in any application where the only temperature
available is the entering oil temperature.
Oil Pressure Drop: Most systems can tolerate a pressure drop through the
heat exchanger of 20 to 30 PSI. Excessive pressure drop should be avoided.
Care should be taken to limit pressure drop to 5 PSI or less for case drain
applications where high back pressure may damage the pump shaft seals.
Oil Temperature
Typical operating temperature ranges are:
Hydraulic Motor Oil 110° - 130°F
Hydrostatic Drive Oil 130° - 180°F
Bearing Lube Oil 120° - 160°F
Lube Oil Circuits 110° - 130°F
50 100 002 003 500
5
1
2
3
4
OIL P MULTIPLIER
OIL VISCOSITY - SSU
OIL
P CORRECTION CURVE
400