PRODUCTS

SPEC SHEETS

CERTIFIER® Air Velocity Calibrator

SERVICE INFORMATION

APPLICATION NOTES

	Calibration of the CERTIFIER Using a Laser Doppler Velocimeter (LDV) (TI-130)
	Using the Model 8495 Transducer Display and Monitor With the CERTIFIER Calibrator (TI-121)

FREQUENTLY ASKED QUESTIONS

1. How big is the CERTIFIER® Air Velocity Calibrator?
   The CERTIFIER® Air Velocity Calibrator is only about 1.5 m (4.75 feet) long and weighs about 15 kg (33 lbs). It is small enough to be placed on top of an ordinary work bench. It is light enough to be carried by one person. When not in use, many people simply stand it on-end in a corner of the room!

   The AIRFLOW open jet wind tunnel is 5.5 meters (18 feet) long. When it is installed in a laboratory it takes up a lot of work space.

   The CERTIFIER calibrator is shipped fully assembled. Shipping weight is about 41 kg (91 lbs). Crate dimensions are approximately 1,700 mm X 825 mm X 880 mm (5.6 ft X 2.7 ft X 2.9 ft).

2. How does the customer install the CERTIFIER® Air Velocity Calibrator in his laboratory?
   The CERTIFIER® Air Velocity Calibrator is shipped fully assembled and ready to use. It can be set up and operating within 30 minutes. The wind tunnel is relatively small and light. It can be placed on top of a work bench and does not have to be attached to the work bench.
3. How does TSI calibrate the CERTIFIER® Air Velocity Calibrator?
   Before each CERTIFIER® Air Velocity Calibrator is shipped, we verify the calibration accuracy of the calibrator using a velocity meter recently calibrated in our standard wind tunnels. The standard wind tunnel traces its calibration to NIST (National Institute of Standards Technology) using laser anemometry.
4. How is the density correction factor calculated?

   To calculate the density correction factor, the user must first measure the barometric pressure and temperature. Once these are measured, they can be input in the following equations:

   English (Imperial) Units:

   K = [(29.92 / P) (460 + T / 530)]

   Where:

   T = Temperature (°F)
   P = Barometric pressure (inches Hg)

   Metric Units:

   K = [(760 / P) (273.15 + T / 294.25)]

   Where:

   T = Temperature (°C)
   P = Barometric pressure (mm Hg)

5. How much technical support will the customer need after the sale?
   Probably none. The CERTIFIER® Air Velocity Calibrator is an extremely simple device to set up and to use. It comes fully assembled and ready to use. It only has two controls: an ON/OFF switch and a speed control. The typical CERTIFIER calibrator user is an experienced calibration engineer and they will be very comfortable with the CERTIFIER calibrator.
6. How often should the CERTIFIER® Air Velocity Calibrator be calibrated?
   The wind-tunnel portion of the CERTIFIER® Air Velocity Calibrator does not need calibration. The dimensions of the wind-tunnel will not change over time. All of the measuring instruments used with the CERTIFIER calibrator, however, must be calibrated on a regular schedule. These instruments include the MKS differential pressure transducer (supplied with the CERTIFIER calibrator), plus the user-supplied thermometer and barometer which are used to calculate the K factor corrections. Independent calibration laboratories who can calibrate these instruments can be found in all countries. The MKS differential pressure transducer should be sent to MKS and NOT sent to TSI for calibration. TSI is NOT equipped to calibrate this device.
7. What about laser calibration?
   We used to calibrate each unit using a laser Doppler velocimeter. However, through nozzle plate design improvements, we have made calibration data for each CERTIFIER® Air Velocity Calibrator the same. Verification of the data using a velocity meter as a transfer standard is important, but we have found that a specific laser calibration for each unit is unnecessary.
8. What factors affect the accuracy of the CERTIFIER® Air Velocity Calibrator's calibration?
   DIFFERENTIAL PRESSURE TRANSDUCER
   The CERTIFIER® Air Velocity Calibrator comes with a precision differential pressure transducer with a convenient LED readout. This provides 0.3% of reading accuracy on the delta P measurement. This high degree of accuracy is needed to produce the lowest possible uncertainty when establishing velocities. Because of control parameter, delta P is proportional to the square root of velocity. The square root proportionality means that for every 1% error in the delta P setting there is only a 0.5% error in velocity.
9. What type of readout is supplied with the CERTIFIER® Air Velocity Calibrator?
   With the CERTIFIER® Air Velocity Calibrator, the user is usually using it to check the calibration of an air velocity meter. Therefore the most convenient way to use the CERTIFIER calibrator is to have the readout display the velocity of the wind tunnel.

   When the CERTIFIER calibrator was first designed it was supplied with a readout that displayed mmHg (from the pressure transducer). The user would then have to look up the pressure reading in a chart to find the corresponding velocity and compare it to the display on the air velocity meter.

   The CERTIFIER calibrator is now supplied with the Model 8495 TRANSDUCER DISPLAY & MONITOR. This monitor allows the user to input the correction factor and obtain direct velocity readings. The TRANSDUCER DISPLAY & MONITOR reads the pressure differential from the transducer and converts it to velocity internally, making calibration checks very easy. All that needs to be done by the user is the calculation of a density correction factor to input into the TRANSDUCER DISPLAY & MONITOR.

10. What types of anemometers can I calibrate in the CERTIFIER® Air Velocity Calibrator?

    The CERTIFIER® Air Velocity Calibrator is designed to calibrate instruments which use thermal anemometry technology. It will work with:

    • TSI 1650 and 1640 Air Velocity Meters
    • All models of VELOCICHECK® Compact Air Velocity Meter
    • All models of VELOCICALC® Meter
    • All TSI series 84XX Air Velocity Transducers
    • Many types of thermal air velocity instruments made by ALNOR®, Kurz, AIRFLOW Instruments®, Testoterm, Kanomax, etc.

    The CERTIFIER calibrator will only work with round probes with a diameter of 16 mm (0.63 in) or less. Probes larger than this will disturb the calibration. The CERTIFIER CALIBRATOR WILL NOT WORK with rotating vane anemometers! If your customer must calibrate rotating vane anemometers they must use an open jet type of calibrator such as the AIRFLOW Instruments or Kurz.