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BM S eries selection

SIZING To properly size a BM TEFC Motor air-cooled oil cooler for industrial equipment, you should first determine some basic parameters associated with your system. HEAT LOAD In many instances the heat load must be determined by using a "total potential" method. This total potential or horse power method is the most common method, and is the simplest way to determine basic heat rejection requirements for hydraulic systems. The total potential is equal to the maximum operating flow and pressure that are generated by the system under full load. To determine the total potential (HP) use the following formula. Note: If the electric motor horsepower of the system prime mover is known, use it as your system potential. HP = [ System Pressure (PSI) x System flow (GPM) ] / 1714 Examples: (1) 7.5 HP 254T frame electric motor driving a pump = 7.50 HP potential (1) HP = (1250 PSI x 10 GPM) / 1714 = 7.30 HP or the total input potential To determine the system heat load in BTU / HR we must use a percentage (v) of the system potential HP. The factor (v) can be calculated by adding up the actual inefficencies of a system; however, for most applications a (v) value of 25% - 30% can be used. Example: 7.50 HP x .30 = 2.25 HP heat To convert the horsepower of heat into BTU/HR use the formula below: HP x 2542 = BTU/HR Example: 2.25 HP Heat x 2545 = 5,729 BTU/HR Applying into a return line For most open loop systems with vane or gear type fixed delivery pumps. To cal - culate the Fs value required when applying the air/oil cooler into a return line use the formula below: Fs = Example = = 123.7 Fs T = Desired system oil temperature leaving the cooler °F t ambient = Ambient air temperature entering the cooler °F Cv = Correction factor for oil viscosity. Example: ISO32 oil @140°F = 1.08 (see chart) APPLYING INTO A CASE LINE In circumstances where the system is a closed loop, or when return line flow is not available, the case drain flow can be utilized to help cool the system. However, in many instances, the case drain flow alone will not be enough to reject all of the heat generated by the system. Case drain lines should not be treated as a normal return lines since the pressure drop allowable usually can vary from 2 - 10 PSI max. Check with your pump manufacturer for the appropriate pressure drop tolerance before applying any cooler. To size the system for case flow or case flow plus any additional flushing loops, please use the following method. Closed loop case drain operating temperatures are normally higher than open loop circuit return line temperatures. BTU/ HR x Cv _______________ T - t ambient 5729 x 1.08 __________ 140 - 90

Formula Tc exit = { T - [ Q / (case flow gpm x 210) ]} Example Tc exit = { 155 - [ 5,729 / (3 x 210) ]} = 145.9 Tc exit = The corrected temperature of the oil exiting the cooler. Fs =

Q x Cv ____________ Tc exit - t ambient

5,729 x 1.08 ___________ = 101.6 145.9 - 90

SELECTION To select a model, locate the flow rate (GPM) at the bottom of the flow vs Fs graph. Proceed upward until the GPM intersects with the calculated Fs. The curve closest above the intersection point will meet these conditions. Examples:

Case Drain Fs = 101.6 GPM = 3.0 Motor size = 254T frame Model = BM - 302

Return Line Fs = 123.7 GPM = 10 "return line flow" Motor size = 324 frame Model = BM - 321

PRESSURE DROP Determine the oil pressure drop from the curves as indicated. For viscosities other than 50 sus at operating, multiply the actual indicated pressure drop (psi) for your GPM by the value in the pressure differential chart for your viscosity.

Examples:

GPM = 10

GPM = 3

Indicated pressure drop Cp correction factor for ISO 32 oil @ 140°F Pressure drop correction

1.4 PSI

1 PSI

1.23

1.4x1.23 = 1.72 psi

1.0x1.23 = 1.23 psi

AIR FLOW CORRECTION CHART In some instances our units are applied tomotors or application where additional or less air flow is available than the flows used for our performance curves. In these instances you can use our air flow correction curves to determine if one of the existing models will work for your application. Example: Follow the preceding examples to properly determine your required Fs. Use the following formula to correct for the difference in air-flow rate. If the calculated Fs = 123.7 and the electric motor were a 1800 rpm 326 frame motor with 250 cfm of air flow, correct as shown. Select the correction factor Cf only from the curve that matches to your electric motor frame size properly. Note: Using a unit that is to small may damage your electric motor due to lack adequate of air flow. Formula Example Fs x Cf = CFs (corrected) CFs = 123.7 x 1.50 (from curve) = 185.6 CFs

Average Liquid Temperature

Cv VISCOSITY CORRECTION FACTORS

1.84 1.67 1.53 1.44 1.39 1.33 1.14 1.02

1.19 1.14 1.09 1.05 1.03 1.01 0.98 0.97

1.56 1.48 1.40 1.34 1.30 1.27 1.09 1.01

1.43 1.39 1.35 1.30 1.26 1.22 1.08 0.99

1.37 1.31 1.27 1.24 1.20 1.17 1.02 0.97

1.26 1.25 1.20 1.17 1.16 1.13 1.01 0.96

1.18 1.16 1.14 1.13 1.10 1.09 1.00 0.96

1.14 1.13 1.11 1.09 1.08 1.06 0.99 0.96

1.08 1.06 1.04 1.03 1.02 1.02 0.98 0.95

100 110 120 130 140 150 200 250

0.85 0.84 0.84 0.83 0.82 0.82 0.80 0.79

0.83 0.80 0.79 0.77 0.76 0.74 0.71 0.69

0.92 0.89 0.88 0.85 0.84 0.83 0.79 0.76

1.11 1.09 1.06 1.04 1.03 1.01 0.98 0.95

1.45 1.40 1.35 1.29 1.25 1.22 1.07 0.99

1.15 1.12 1.10 1.08 1.05 1.04 0.99 0.96

1.25 1.20 1.17 1.13 1.11 1.09 1.01 0.97

1.38 1.32 1.27 1.24 1.19 1.16 1.04 0.98

Average Liquid Temperature

Cp PRESSURE DROP CORRECTION FACTORS

2.00 1.70 1.50 1.40 1.30 1.20 0.93 0.81

8.80 6.70 5.60 4.50 3.70 3.10 1.60 1.05

2.40 2.10 1.80 1.60 1.50 1.30 0.96 0.82

4.40 3.60 3.00 2.60 2.23 1.90 1.20 0.92

0.730 0.720 0.709 0.698 0.686 0.676 0.635 0.556

100 110 120 130 140 150 200 250

6.40 5.10 4.20 3.40 2.90 2.50 1.40 0.97

1.07 1.04 1.02 0.99 0.97 0.95 0.89 0.85

1.53 1.45 1.38 1.30 1.23 1.17 0.99 0.93

1.82 1.72 1.60 1.49 1.38 1.30 1.08 0.96

2.54 2.35 2.15 1.94 1.75 1.61 1.18 1.03

4.19 3.73 3.26 2.80 2.38 2.04 1.33 1.11

6.44 5.70 4.91 4.14 3.47 2.90 1.59 1.21

9.38 8.33 7.23 6.19 5.20 4.35 1.74 1.22

13.56 11.63

1.26 1.20 1.14 1.08 1.03 0.98 0.90 0.83

3.00 2.40 2.10 1.90 1.90 1.70 1.20 1.00

3.50 2.90 2.50 2.20 2.00 1.90 1.30 1.05

9.73 7.80 6.11 4.77 1.95 1.23

note: AIHTI reserves the right to make reasonable design changes without notice.

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355 American Industrial Drive LaCrosse, VA 23950

tel: 434-757-1800

fax: 434-757-1810

email: sales@aihti.com

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