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 the DP-Calc™ Micromanometer?
The DP-Calc™ Micromanometer can be connected to a Pitot tube. In velocity mode, the DP-Calc™ Micromanometer will read velocities from 250 to 15,500 ft/min (1.27 m/s to 78.7 m/s). Measuring velocities below 1000 ft/min (5.08 m/s) is not recommended. The Pitot tube is most accurate at velocities above 2000 ft/min (10.16 m/s).
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 the instruments read low velocities?
The velocity specification on the DP-Calc™ Micromanometers is from 250 to 15,500 ft/min. A Pitot tube is necessary to make the velocity measurement. Velocity is not measured directly; it is converted from pressure. The conversion provides high resolution at high pressures and low resolution at low pressures, making velocity measurements below 1,000 ft/min inaccurate and impractical. The DP-Calc™ Micromanometers read to 250 ft/min for people who want an estimate of the velocity below 1000 ft/min, but do not need an accurate reading.
Can the micromanometers be connected to a computer?
Yes. Both the micromanometers can be interfaced to a computer through the serial connector using the provided Computer Interface Cable. The Model 8702 requires the customer to develop a means of capturing data on computer. The Model 8705 can download data stored in memory to a computer using LogDat™ Downloading Software, which is included with the instrument.
Can the micromanometers be connected to a printer?
Both DP-Calc™ Micromanometers 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 micromanometers use rechargeable batteries?
Yes. You can use rechargeable batteries in all TSI micromanometers.
Can you measure a continuous analog output on the DP-Calc™ Micromanometers?
No. There is no output jack to monitor the analog output voltage.
Do the micromanometers read standard or actual velocity?
The Model 8702 and 8705 read a nominal velocity that is neither standard nor actual, but a combination of both. This is the velocity that is read by any Pitot tube and pressure device that doesn't do a density correction. The Model 8705 allows entry of barometric pressure and temperature. This DP-Calc™ Micromanometer will then calculate actual/standard velocity for you.
Do the micromanometers recharge batteries in the instrument?
No. Rechargeable batteries must be externally charged.
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 micromanometers?
The micromanometers all have a two-year warranty. See the instruction manual for details.
How often should I recalibrate my micromanometer?
To maintain a high degree of accuracy in your measurements, TSI recommends that you return your instrument to the factory for an annual recalibration.
Is there memory in the DP-Calc™ Micromanometer so that data can be stored and downloaded later?
The Model 8705 DP-Calc™ Micromanometer can store up to 500 test ID's and up to 1000 samples. This data can be recalled on the display of the DP-Calc™ Micromanometer, or it can be downloaded to a computer using the downloading software provided with the instrument. The Model 8702 DP-Calc™ Micromanometer is designed to take samples and average readings. Specific samples can be recorded with a printer. In order to view data points after the initial measurement, 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 Model 8702 DP-Calc™ Micromanometer to allow later recall of the individual data points.
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 does your two-part accuracy specification actually mean for the DP-Calc™ Micromanometer?
The accuracy is the sum of the two components of the accuracy spec. For example, the DP-Calc™ Micromanometer Model 8702 has an accuracy rating of ±1 percent of reading and ±.005 inches H2O. If your DP-Calc™ Micromanometer reads 1.000 inches H2O, ±1 percent of reading is ±0.01 inches H2O, plus ±0.005 inches H2O for a total tolerance of ±0.015 inches H2O. The combined accuracy is ±1.5 percent at 1.000 inches H2O.
What is considered a high velocity?
Any velocity over 1,000 ft/min.
What is the purpose of the software included with the DP-Calc™ Micromanometer?
The software included with the DP-Calc™ Micromanometer downloads data stored in the memory of the DP-Calc™ Micromanometer. The data is downloaded to a data file in a comma-delimited format so it can be imported into any commercial spreadsheet.
What is the repeatability of TSI instruments?
The repeatability is included in the accuracy specifications.
What standards do the micromanometers comply with?
Instruments are supplied with a certificate of calibration traceable to the National Institute of Standards and Technology (NIST) and also comply with MIL standard 45662A.
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.