BAE - SWSI & DWDI Airfoil Fans - Twin City Fan & Blower

Piezometer Ring (Airflow Measuring System)A piezometer ring is available on model BAE fans, aswell as other Twin City Fan housed and plenum fans,as part of an airflow measuring system, based onthe principle of a flow nozzle. The inlet cone of thefan is used as the flow nozzle. The flow can be calculatedby measuring the pressure drop through theinlet cone. No tubes or sensors are inserted in thehigh velocity airstream which could obstruct airflow.The system, consists of a piezometer ring mountedat the throat and a static pressure tap mounted onthe face of the inlet cone. A differential pressuretransducer and digital display can also be provided.The pressure drop is measured from the tap locatedon the face of the inlet cone to the piezometer ringin the throat. The inlet tap is connected to the highpressureside of the transducer and the piezometerring is connected to the low-pressure side.Based on Twin City Fan laboratory tests, the systemwas determined to be accurate within +/-5%.Refer to Twin City Fan Engineering SupplementES-105.FlowMeasurementSystemPiezometer RingMounted at Throatof Inlet ConeNOTE: Twin City Fan does not recommend placementof flow measuring probes inside the fan inlet cone inthe path of airflow. These devices create disturbancesand unpredictable performance losses. Twin CityFan will not be responsible for loss of performancedue to such devices.Performance Correction for Temperature & AltitudeThe performance tables in this catalog are basedon fans handling standard air at a density of 0.075pounds per cubic foot. This is equivalent to air at70°F at sea level (29.92" Hg barometric pressure).When specified performance is at a density differentthan standard, it must be converted to theequivalent standard conditions before the fan can beselected from the performance tables. The equivalentstandard conditions can be calculated by using theTemperature and Altitude Density Ratios shown in thetable below.Temperature and Altitude Density RatiosAIRTEMP°FALTITUDE IN FEET ABOVE SEA LEVEL0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 20000BAROMETRIC PRESSURE IN INCHES OF MERCURY29.92 28.86 27.82 26.82 25.84 24.90 23.98 23.09 22.22 21.39 20.58 16.89–50 1.293 1.247 1.201 1.159 1.116 1.076 1.036 0.997 0.960 0.924 0.889 0.7290 1.152 1.111 1.071 1.032 0.995 0.959 0.923 0.889 0.856 0.824 0.792 0.65050 1.039 1.003 0.967 0.932 0.897 0.864 0.833 0.801 0.772 0.743 0.715 0.58670 1.000 0.964 0.930 0.896 0.864 0.832 0.801 0.772 0.743 0.714 0.688 0.564100 0.946 0.912 0.880 0.848 0.818 0.787 0.758 0.730 0.703 0.676 0.651 0.534150 0.869 0.838 0.808 0.770 0.751 0.723 0.696 0.671 0.646 0.620 0.598 0.490200 0.803 0.774 0.747 0.720 0.694 0.668 0.643 0.620 0.596 0.573 0.552 0.453250 0.747 0.720 0.694 0.669 0.645 0.622 0.598 0.576 0.555 0.533 0.514 0.421300 0.697 0.672 0.648 0.624 0.604 0.580 0.558 0.538 0.518 0.498 0.480 0.393350 0.654 0.631 0.608 0.586 0.565 0.544 0.524 0.505 0.486 0.467 0.450 0.369400 0.616 0.594 0.573 0.552 0.532 0.513 0.493 0.476 0.458 0.440 0.424 0.347450 0.582 0.561 0.542 0.522 0.503 0.484 0.466 0.449 0.433 0.416 0.401 0.328500 0.552 0.532 0.513 0.495 0.477 0.459 0.442 0.426 0.410 0.394 0.380 0.311550 0.525 0.506 0.488 0.470 0.454 0.437 0.421 0.405 0.390 0.375 0.361 0.296600 0.500 0.482 0.465 0.448 0.432 0.416 0.400 0.386 0.372 0.352 0.344 0.282650 0.477 0.460 0.444 0.427 0.412 0.397 0.382 0.368 0.354 0.341 0.328 0.269700 0.457 0.441 0.425 0.410 0.395 0.380 0.366 0.353 0.340 0.326 0.315 0.258750 0.439 0.423 0.407 0.393 0.379 0.365 0.351 0.338 0.326 0.313 0.303 0.248800 0.420 0.404 0.389 0.375 0.362 0.350 0.336 0.323 0.311 0.300 0.290 0.237850 0.404 0.391 0.376 0.363 0.349 0.336 0.324 0.312 0.300 0.289 0.279 0.228900 0.389 0.376 0.363 0.349 0.336 0.324 0.312 0.300 0.289 0.279 0.268 0.220950 0.376 0.363 0.350 0.337 0.325 0.313 0.301 0.290 0.279 0.269 0.259 0.2121000 0.363 0.350 0.338 0.325 0.314 0.302 0.291 0.280 0.270 0.259 0.250 0.205www.tcf.com11