# Testo - Multifunction Measuring Instruments

Online Marketing Executive en Testo Limited
1 de Nov de 2011
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### Testo - Multifunction Measuring Instruments

• 1. Committing to the future 2011 Multi-Function Measuring Instruments °C %RH m/s hPa CO2 Lux CO aW rpm mA V
• 2. Information Measurement Engineering For Multi-Function Measuring Instruments Measurement and application ranges of flow probes Probe selection Measurement and application ranges of flow probes The flow measurement range 0 to 100 m/s can be divided into three sections: – Low-speed velocity 0 to 5 m/s 100 – Mid-speed velocity 5 to 40 m/s Thermal Vane measurement Vane/temperature Pitot Pitot probe probes to +60 °C measurement tube to tube – High-speed velocity 40 to 100 m/s. to +70 °C probes +600 °C NiCr-Ni Thermal probes are used for accurate measurements in the range 0 to 5 m/s. Vane -40°C 60 +600 °C probes are ideal for velocities from 5 to 40 m/s. The measuring range of the Pitot to to tube depends on the differential pressure probe used. The new 100 Pa probe can +140 °C +350 °C therefore be used for the exact measurement of flow speed from approx. 1 m/s to 12 m/s. The Pitot tube yields optimum results in the higher velocity range. An 40 additional criterion when selecting the right velocity probe is the temperature. Thermal sensors can normally be used at up to approx. +70 °C. Special design vane probes can be used to maximum +350 °C. Pitot tubes are used for 20 temperatures above +350 °C. 15 10 0 Supply/Returns Positioning in air current The air vent greatly changes the relatively The vane probe is set exactly if the flow direction uniform flow inside the duct. Areas of ar is parallel to the vane axis. If the measuring probe higher flow velocity are created at the Lamin is turned slightly in the air current, the value flow free vent surfaces and areas of low in the e of the shown in the instrument changes. The measuring flow velocity and swirl at the grids. centr t probe is positioned exactly in the air current if the duc The flow profile steadies at a value shown is at max. distance from the the grid When measuring in a duct there should also be a depending on the grid design but is minimum of ten diameters of straight run before usually 20 cm. For best accuracy, a Max. values the measuring spot and four diameters of straight large diameter vane is recommended. run after the spot for best results. By design, Min. values The area of the vane helps to get an vanes are less influenced by turbulence than thermal probes or Pitot tubes. Mean values average reading of the turbulent flow from the grid. Site selection Direction of flow D Measurements at suction apertures using a volume flow funnel 10 x D 4xD Even without the disturbing effects of a grid in an aperture, the lines of flow are not directional and the flow profile is irregular. Because a partial vacuum in the duct You should measure in a straight part of the duct, if possible. The duct part should draws air out of the room in a funnel shape even a short distance from the aperture, have a minimum of ten diameters of straight run before the measuring spot and there is no defined area in the room over which a measurement could be made. four diameters of straight run after the measuring spot. The flow profile should not Therefore, only the duct or funnel measurement yields reproducible results. be interrupted in any way by flaps, dips, angles etc. Measuring funnels of various sizes are available for such applications. These create defined flow conditions at a known distance from the grid with a fixed volume. A velocity probe is positioned centrally and secured. The volume flow is calculated from the velocity multiplied by the funnel factor (e.g. funnel factor 22). Flow measurement in ducts As part of approval measurements, indirect measuring procedures (grid measurements) are used to measure air flows. The following procedures are suggested in VDI 2080/EN 12599: – Trivial procedure for grid measurements in square cross-sections. – Centroidal axis procedures for grid measurements in circular cross-sections – Loglinear procedure for grid measurements in circular cross sections. Measuring ambient air velocity using testo 400 in accordance with DIN 1946 Part 2, ANSI/Ashrae 55-1992 Ambient air velocity is a very important parameter in the thermal comfort of people Ambient air velocity in rooms. testo 400 supplies the current and mean air velocities. The maximum Air temperature in °F permissible mean air velocity depends on the air temperature measured by testo 68 70 72 74 76 78 80 1,7 140 Mean air velocity m/s 400 and the amount of turbulence calculated from the air velocity. The example shows a permissible mean air velocity of 0.26 m/s with an air temperature 1,6 120 measured at 24.4 °C and an automatically calculated degree of turbulence of 10 %. 1,5 0% 100 0,4 80 Mean air velocity fpm 10% 0,3 60 20% 40% 0,2 40 60% 0,1 20 0 0 20,0 21,1 22,2 23,3 24,4 25,5 26,7 Air temperature in °C 2 Degree of turbulence T
• 3. Contents Measuring instruments Practical multi-function measuring instrument testo 435-1/-2/-3/-4 All-rounder for ventilation and indoor air quality Page 4 Measurement systems testo 445 Service instrument for ventilation/air conditioning systems Page 8 testo 400 The reference measuring instrument for A/C and ventilation systems Page 13 Accessories Software and Accessories Page ComSoft 3 - Professional Professional Software including Data Filing 24 Printer Page Testo fast printer Versatile infrared printer for testo 435, 445, 400 26 Ethernet adapter Page Ethernet adapter Access Ethernet with Testo measuring instruments 27 3