Are there K-factors available for portables to calculate volumetric flows?
No. To calculate the volumetric flows, the reading should be taken inside the duct; or it is better yet to use the Model 8370 AccuBalance® Flow Measuring Hood.
Can a customer recalibrate his/her own unit?
Yes and no. When the unit is calibrated, an EEPROM is programmed with the calibration data. A customer cannot do a full calibration in the field. However, a field calibration adjustment is possible through the software. Again, this is not a full calibration. TSI recommends a full annual calibration. See Application Note TI-112 for details.
Can a pitot tube be used with your instruments?
Models 8385 and 8386 can be connected to a pitot tube. In the pressure mode, the VelociCalc® Plus meter will read pressures from -10 to +10 inches H2O (-2.5000 to +2.500 kPa or -20.00 to +20.00 mmHg).
Can I buy the printer paper somewhere other than TSI?
Yes. Any thermal paper with the dimensions of width 2-1/4 inches and an outside roll diameter of not larger than 1 inch will work for the Portable Printer.
Can I get a remote read-out?
No. None of the micromanometers have remote readout capabilities.
Can portable air velocity meters use rechargeable batteries?
You can use rechargeable batteries in all of the portables except for the Model 8340 NOTE: Rechargeable batteries will nullify the intrinsic safety rating on the Model 8340. Also, rechargeable batteries don't last as long as alkaline batteries.
Can the portable air velocity meters be connected to a printer?
Most TSI hand-held instruments (with the exception of Model 8330 and 8340) can be used with a printer supplied by TSI or any printer that will accept an RS-232 serial input. TSI printers include a properly wired interface cable; non-TSI printers may require a special cable.
Can the portable meters be connected to a computer?
The VelociCalc® and VelociCalc® Plus meters can be interfaced to a computer through the serial connector using the optional Model 8940 Computer Interface Cable. The VelociCheck® meters cannot be connected to a computer.
Can the VelociCalc® and VelociCheck® instruments read to zero ft/min?
The low end of the velocity specification for the VelociCalc® meters is 30 ft/min (0.15 m/s). The units will read air velocities between zero and the minimum specified, however, the accuracy is uncertain.
Can you measure a continuous analog output on the VelociCalc® Meters?
No. There is no output jack to monitor the analog output voltage.
Do the air velocity meters recharge batteries in the instrument?
No. Rechargeable batteries must be externally charged.
Do you need to correct for humidity?
There is no need to correct for humidity because humidity has very little affect on velocity readings. Studies show there is less than a 3-percent change in the velocity reading while the humidity changes from 0 to 100-percent RH in air at room temperature.
Does TSI offer a model to be used in high temperatures?
The Model 8702 and 8705 can be used when connected to a Pitot tube in a high temperature, high velocity environment.
How do you measure delta P?
Delta P is a phrase commonly used to describe differential pressure. Differential pressure can be measured with a DP-Calc™ Micromanometer by connecting the tubing to the pressure ports on the back of the unit. The ends of the tube are placed at the points where you want to measure delta P.
How long is the warranty period for the portable air velocity meters?
The portable air velocity meters all have a two-year warranty. See the instruction manual for details.
How often should I recalibrate my Portable Air Velocity Meter?
To maintain a high degree of accuracy in your measurements, TSI recommends that you return your instrument to the factory for an annual NIST traceable recalibration.
Is there a more rugged version for operating in dirty environments -- in exhaust stacks, chemical acid baths, etc.?
The portable air velocity meters are designed to operate in clean environments. If used in a dirty environment, dirt will collect on the sensor and change the calibration. Corrosive environments will damage the sensor.
Is there any software available for the VelociCalc portables?
No. There is no software available from TSI for the portables. Any software will have to be written by the end user or an outside source.
Is there memory in the VelociCalc® Meter so that data can be stored and downloaded later?
No. The VelociCalc® meters are designed to store only statistics of a set of readings. Data can be recorded with a printer. In order to store data for later recall, it is necessary to capture the data with a data logger or personal computer at the serial port as each reading is taken. No data logging occurs within the VelociCalc® meters to allow later recall of the individual stored readings.
Please explain NIST traceability
NIST is the National Institute of Standards and Technology. All test and calibration data supplied by TSI has been obtained using standards whose accuracies are traceable to NIST or has been verified with respect to instrumentation whose accuracy is traceable to NIST.
What are density corrections?
In general, there are two ways to express air velocity: standard velocity and actual velocity. Standard velocity is velocity that is referenced to standard conditions. Actual velocity is the speed at which a microscopic particle of dust would be traveling as the air flow carries it along. The two measurements give the same readings if actual conditions equal standard conditions. However, if the temperature increases, the air would expand and become thinner. Actual velocity would then be higher than standard velocity. The Model 8705 DP-Calc™ Micromanometer can display either actual or standard velocity when barometric pressure and temperature are entered.Density Correction Factor = ((460+70)(P)) / ((460+T)(406.8))whereT = ambient temperature in degrees FahrenheitP = ambient pressure in inches H2O.If you use metric units, the equation becomes:Density Correction Factor = ((273.15+21.1)(Pm)) / ((273.15+Tm)(101.3))whereTm = ambient temperature in degrees CentigradePm = ambient pressure in kPa.The density correction factor will generally be a value in the range of 0.3 to 1.7, depending on the ambient conditions.
What are the accuracy specifications of these VelociCalc® meters?
The VelociCalc® meter velocity accuracy specifications are ±3 percent of reading or ±3 ft/min, whichever is greater. The temperature accuracy specifications are ±0.5°F (±0.3°C).
What are the electronics operating temperature limits for the VelociCalc® meters?
For all models it is 40° to 113°F (5° to 45°C).
What are the probe operating temperature limits of the VelociCalc® Meters?
Models 8345/8346/8347/8347(A) have a probe operating temperature range of 0° to 200°F (-17.8° to 93.3°C).
What do the TIME CONSTANT or SAMPLE INTERVAL keys on the VelociCalc® and VelociCalc® Plus meter actually do?
This feature allows you to change the display dampening. You have the option to select a 1, 5, 10, 15, or 20-second average. In each case, the display will update velocity readings every second. The displayed values are a moving or running average of the measured velocity. Selecting a larger time constant will reduce fluctuations on the display.
What does it mean if a unit is temperature compensated?
In a constant flow, the output readings remain constant across a range of temperatures as long as those temperature changes are within the temperature-compensated range.
What does the time constant key on the VelociCalc® Meters actually do?
The time constant key has two functions, the first of which is changing the display dampening. You have the option to select 1, 5, 10, 15, or 20-second average. In each case, the display will update velocity readings every second. The displayed values are a moving average or running average of the measured velocity. If velocity readings are fluctuating, select a longer time constant to reduce the fluctuations.
What does your two-part accuracy specification tell me for the VelociCalc® Air Velocity Meter and VelociCheck® Comput Air Velocity Meter?
The accuracy is the greater of the two components of the accuracy specification. Example: The VelociCalc® Plus Air Velocity Meter Model 8386 has an accuracy rating of ±3 percent of reading or 3 ft/min, whichever is greater. If your VelociCalc Plus meter reads 1,000 ft/min, ±3 percent of reading is ±30 ft/min. Since this is larger than ±3 ft/min, the accuracy specification at 1000 ft/min is ±30 ft/min.
What is considered a high velocity?
Any velocity over 1,000 ft/min.
What is the repeatability of TSI instruments?
The repeatability is included in the accuracy specifications.
What standards do the portable air velocity meters comply with?
Units are supplied with a certificate of calibration traceable to the National Institute of Standards and Technology (NIST NOTE: Rechargeable batteries will nullify the intrinsic safety rating on the Model 8340. Also, rechargeable batteries don't last as long as alkaline batteries.
What type of calibration facility is used at TSI to calibrate instruments?
TSI calibrates in wind tunnels that have been verified with a Laser Doppler Velocimeter for accuracy. This is the same technique used by NIST for their low-velocity calibration facilities.
What type of special versions are available for portable air velocity meters?
The family of portable air velocity meters offers a wide variety of features and ranges to meet the needs of most applications; therefore, no special versions are available.
Why aren't the probes field replaceable?
Replacing a probe requires calibration, temperature compensation, replacing resistors, etc. Very few customers have the capability to do these operations.
Why can't I read velocity and temperature at the same time?
On the VelociCalc® Plus Meter models you can read velocity and temperature at the same time. Temperature displays in the upper left corner of the display while the velocity displays in larger size on the lower half of the display. However, on earlier Models, the thermal anemometer and the temperature sensor were placed within close proximity and the thermal anemometer affected the temperature of the surrounding air. When velocity is being taken, temperature readings read too high. With the VelociCalc Plus meter, the temperature sensor is placed further away from the thermal anemometer to avoid this phenomenon.
Why do humidity measurements take longer than other measurements?
Humidity measurements generally take longer than others to stabilize because of the nature of humidity and air movement. The length of time it takes to stabilize depends on the environment the probe was in before measurements are taken. Going from a very humid environment to a drier environment will take longer to stabilize than going from a dry environment to a humid one. That is why TSI recommends you store your instrument in a cool, dry environment. Stabilization time can be reduced by gently waving the wand back and forth.
Why do the readings fluctuate?
The pressure sensor in our micromanometers responds quickly to changes. The fluctuating readings you see are actually variations in the pressure. To reduce the fluctuation, select a longer time constant to dampen the display or move the sensor into a less turbulent area.