Type 4 -
The 'oldest' instrument in our range, the Type 4 has proved its worth over nearly twenty years of steady development. Literally thousands are now in use throughout the world, and demand increases every year. Based on two precision swivelling limb Micromanometers, the test set covers 0 to 5000 Pascals (0 to 20 in. H2O) with a total of seven limb positions, and has a resolution considerably better than 0.25 Pascals (0.001 in. H2O) on the most sensitive setting. A plate mounted inside the case gives details of the range covered by the various limb positions. The need for such a wide range of precision measurement is convincingly demonstrated by considering the example of a high pressure air distribution system, where the centrifugal fan can generate over 2000 Pascals (8 in. H2O) in the plant room. In the smaller duct runs the static pressure may be only a tenth of this, and if it is necessary to investigate pressure losses around bends and transitions these could well be only 1 or 2 Pascals (0.004 or 0.008 in. H2O). To cope adequately with this range of pressures would normally require an untidy collection of at least 3 fixed range manometers! The Pressure Scales The instrument is assembled with pascal (N/m²) scales, but loose, easily interchangeable scales in mm H2O and inches w.g. are included to suit the user. Millibar scales are available to special order. Velocity Scales Velocity scales calibrated in metres per second and feet per minute are supplied. These particularly handy items, used with a pitot static tube, eliminate calculations when using the test set for measurement of ducted air velocities at or near 'standard' temperature and pressure (20°C/1013 mbar or 68°F/30 in Hg). Velocity Calculator