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TEK-AIR TECHNICAL PRODUCT DATA SHEET …

VorTek SensingVelocity measurement is accomplished by TEK-AIR 's unique, patentedVorTeksensors. VorTeksensors utilize an industry proven vortexshedding phenomena to measure the true airflow velocity independentof changes in temperature, density and humidity, which effect pitotand thermal airflow measurement requirements for accuracy and reliability have focused attentionon the limitations of conventional, pneumatic type pitot arrays. Awareof these limitations and the limitations of electronic thermal airflowtransmitters, TEK-AIR developed and patented the Sensing: How It WorksThe vortex shedding phenomena can be witnessed all around us ineveryday life. Swirling vortices, or eddy currents are generated when-ever air or liquids flow around an obstruction in their flow examples are the eddy currents which develop behind rocksin a stream, and the fluttering of a flag behind a flag pole.

VorTek Sensing Velocity measurement is accomplished by Tek-Air's unique, patented VorTek sensors.VorTek sensors utilize an industry proven vortex shedding phenomena to measure the true airflow velocity independent

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Transcription of TEK-AIR TECHNICAL PRODUCT DATA SHEET …

1 VorTek SensingVelocity measurement is accomplished by TEK-AIR 's unique, patentedVorTeksensors. VorTeksensors utilize an industry proven vortexshedding phenomena to measure the true airflow velocity independentof changes in temperature, density and humidity, which effect pitotand thermal airflow measurement requirements for accuracy and reliability have focused attentionon the limitations of conventional, pneumatic type pitot arrays. Awareof these limitations and the limitations of electronic thermal airflowtransmitters, TEK-AIR developed and patented the Sensing: How It WorksThe vortex shedding phenomena can be witnessed all around us ineveryday life. Swirling vortices, or eddy currents are generated when-ever air or liquids flow around an obstruction in their flow examples are the eddy currents which develop behind rocksin a stream, and the fluttering of a flag behind a flag pole.

2 The flag andthe flag pole provide the most visual example of how vortex sheddingworks. The flag pole (see fig. 1) presents an obstruction in the path ofthe airflow , which is the wind. As wind passes around the flag pole,vortices (eddies) are created in the wake of the DescriptionTheVorTek 5000airflow measuring device consists of multi-sensor probes which are inserted in the ductwork where airflowis to be measured and transmitted. Individual sensors on theprobes provide pulse type electronic output signals which aredirectly proportional and linear to the airflow velocity. Thesedigital signals are totalized in the companion transmitter andconverted to an industry standard, 4-20mA output.

3 ( VDC or2-10 VDC are also selectable by jumper).Probe and sensor quantities are selected on the basis of ductsize to provide an accurate and repeatable instantaneous airflowtraverse. Sensors also incorporate integral shrouds for thereduction of turbulence at the sensing points. Cables areprovided for the connection of individual probes to thetransmitter, eliminating the need for complex field VorTektransmitter operates on industry standard 24 VACpower with less than 8 VA power consumption. Transmitteroutput is fully isolated to prevent ground loop problems in thereceiving calibration standard is provided in the transmitter toallow for the calibration of the unit in the field.

4 Diagnosticfunctions are provided to allow for on-line zero and 's VorTek 5000airflow measuring device is designed foruse in applications where the reliable and accurate measurementof airflow in ducts is required over a wide range of applications include VAV fan synchronization, cleanroom control, filter monitoring, and laboratory Systems, Eagle Road Danbury, CT 06810 (203) 791-1400 FAX: (203) 798-6534 SALESFAX: (203) 730-9564 7-05 Electronic airflow measurement device designedspecifically for the reliable measurement of air-flow in ducts over a wide range of operating conditions. Unique patented sensing principle Linear velocity averaging Insertion probes AC power Duct case optional Wide range of operation Stable, drift-free operation Internal diagnostics Jumper selectable outputVorTek VT5000 VORTEX FLOW TECHNOLOGY MEASUREMENTUS PATENT # 4,770,035 TEK-AIR TECHNICAL PRODUCT data SHEETTek-Air Systems, Eagle Road Danbury, CT 06810 (203) 791-1400 FAX: (203) 798-6534 SALES FAX: (203) 730-9564 7-05 VorTek airflow measurement Device VT5000 These vortices, in accordance with the laws of nature, aredeveloped and shed in an alternating manner, from one side ofthe flag pole to the other.

5 The evidence of the shedding ofvortices is in the waving of the flag conditions required to create stable and repeatable vortexshedding were determined in the early 1900's by T. vonKarmen; hence stable vortices are termed "Karmen vortices". TEK-AIR 's unique VorTeksensors generate stable, repeatableKarmen vortices over a wide range of (see fig. 2) operate in the following in the duct enters the directional shroud which helpsdirect any airflow . airflow then passes around the trapezoidalshedder, creating alternating high and low pressure vortices. Atrapezoid is used because it is the most effective shapedobstruction for creating strong alternating vortices and"pulses".

6 Sensing ports on opposite sides of the shedder relaythese pressure pulses via tubing to pulse detectors whichoutput a digital signal to the electronics. The electronicsconvert these digital pulses to analog output and Advantages of the VorTekAirflow Measuring DeviceThe VorTekairflow measuring device offers many advantagesover conventional analog devices such as pitot arrays withvelocity pressure transmitters and thermal techniques. Unlikethese analog measurement techniques, VorTeksensors providedigital pulse outputs at a frequency which is linear to theairflow velocity. Velocity averaging becomes a simple matter oftotalizing pulses from individual sensors to effect an instanta-neous duct SensorThe VorTekdevice utilizes a sensing technique called vortexshedding to measure airflow velocity.

7 Sensors provide truelinear outputs, true velocity (not pressure) averaging, andinsensitivity to dirt and dust. Benefits include high flow turndowns,drift free operation, shock resistance, insensitivity to normal temper-ature, pressure, and humidity variations, plus the ability to calibrateover the entire range of Range of OperationVorTek 5000sensors operate over the range of 400 to 7000 feetper minute. Because the sensor's signals are linear, the electronictransmitter can be calibrated to operate over this entire range,unlike velocity pressure transmitters, which must be replaced ifmajor range changes are needed. The digital frequency outputfrom the VorTeksensors is directly proportional to the velocity ofthe air flowing in the vicinity of a sensor.

8 This inherent linearitysimplifies the averaging and totalizing process, reducing theamount of complicated electronic circuitry required. It also pro-vides for uniform accuracy over the entire range of Velocity AveragingUnlike pitot arrays which average nonlinear velocity pressuresignals pneumatically, the VorTektransmitter averages true veloc-ity as recommended in the ASHRAE ElectronicsEach VorTekairflow transmitter incorporates modular units, regardless of the application or options, utilize thecombination of two or three circuit boards. Simple plug-in program modules are used to configure the transmittersfor a particular FeaturesTo simplify setup, calibration, and troubleshooting, severaldiagnostic features are provided.

9 These include the ability tocheck transmitter zero on-line, check sensor performance, andcalibrate electronics with the internal frequency ApplicationsAirflow measurement and control for: Semiconductor labs, R & DFacilities, Labs and Hospitals, and Process 1 Figure 2 Shedding Vortices Cause Flag to WaveObstruction(Flag Pole)VorticesShedderSupport BarDirectional ShroudAIRFLOWT ubingTek-Air Systems, Eagle Road Danbury, CT 06810 (203) 791-1400 FAX: (203) 798-6534 SALES FAX: (203) 730-9564 7-05 VorTek airflow measurement Device VT5000 Figure 3 NOTE: At minimum requirements, optimum accuracy should not be expected. Optimum installation for any flow device is 8 diameter upstream, 3 diameter downstream of any Minimum Installation RequirementsSpecificationsSensorsAccurac y*+/- readingInterchangeability+/- Limits304 Stainless Steel-20 F to 200 FHigh Temp.

10 F to 320 FAluminum-20 F to 140 FCPVC-20 F to 140 FVelocity Range**400 to 7000 fpmHumidity Limitsnon-condensingConstructionAluminum , CPVC, 304 , 316 accuracy specified is representative of controlled test conditions. The installed accuracy typically observed is subject to actual upstream and downstream conditions, and the accuracy of the field instruments used for verification which is typically +/- 5% ofreading or recommended minimum velocity range for control applications is 450 +/- full scaleRange (adjustable)**400 to 7000 fpmInput1 to 16 sensorsOutput4-20mA standard(1-5V & 2-10 VDC optional)Power24 VAC +/- 20%, 8 VA, 50/60 HZ, 15-35 VDCLoad Limits650 ohms Frequency122 HzTemperature Range25 F 10 125 FTemperature Error< +/- over 25 F to 125 FHumidity LimitsNon-condensingEnclosureEquivalent to NEMA 1 Optional NEMA 4 Cables10' standard (longer available)


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