58
3. Cooling
3.1
DYNAMOMETER COOLING
Proper cooling of the dynamometer is essential to ensure a long operating life and accurate measuring
results. All Magtrol WB/PB Series Dynamometers* are water-cooled to guaranty the best possible
heat dissipation.
Note:
PB 2.7 Series Dynamometers are available with a cooling circuit (K) or
without a cooling circuit.
3.1.1
c
onnectionS
WARNING: THE COOLING TUBES MUST HAVE AN INSIDE
DIAMETER IN ACCORDANCE WITH THE INDICATIONS
ON THE CORRESPONDING DYNAMOMETER DATA
SHEETS (
SEE SECTION 1.2
). THEY MUST BE FITTED TO
THE DYNAMOMETER USING A METAL RING. ALSO,
CHECK FOR CORRECT WATER FLOW DIRECTION.
The cooling water input is marked “
C
ooling
water
inlet
” on the dynamometer housing. The other
nipple is used for the water outlet. Check for correct connections.
3.1.2
W
Ater
F
loW
And
P
reSSure
The required cooling water flow rate can be worked out by means of the following formula:
Braking Power [kW] · 860 [l·°C/kWh]
Flow rate [l/h] =
Outlet Water Temperature [°C] − Inlet Water Temperature [°C]
Note:
1 kWh = 860 kcal = 3600 kJ
The dynamometer cooling system has been designed for an open outflow and freely flowing water
without back-pressure. The maximum input pressure must not exceed 2 bars for models WB/PB
15, WB/PB 115 and WB/PB 65. The maximum input pressure must not exceed 0.5-0.8 bars for
models WB/PB 2.7 and WB/PB 43. A pressure valve can be added to the cooling system of the
brake upon request.
3.1.3
c
ooling
W
Ater
c
onSumPtion
≈
30 l/kWh at
Δ
t = 30 °C (Metric)
≈
8 gal/kWh at
Δ
t = 86 °F (US)