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.Tips for temporary mounting are also available, with a magnet to holdthe tube to magnetic sheet metal.Connections are available for rubberhoses or metal tubing.Manometers of Inclined Vertical TypeManometers of inclined/vertical type are available with red-read-ing dual scales for pressure in inches of water and velocity in feet perminute at 70°F.These manometers may be machined from acrylic plasticwith a bubble level and leveling screws, and use red guage oil.A range of400 to 9,000 feet per minute with 0.01" water column divisions in the in-clined section, and 0.10" water column divisions in the vertical section,will cover most needs.Ranges up to 19,000 feet per minute are availablebut with less precision in scale divisions when using blue guage oil.Steelcarrying cases with space for hoses, extra guage oil, and Pitot tubes up to36" are available and are necessary to properly carry the manometer.Balancing ConesCones for airflow measurement through air distribution products,such as ceiling and wall inlets and outlets, are available in sets of gradu-ated sizes to fit over various sizes of inlets and outlets.The cones directairflow over a direct-reading airflow meter in the apex of the cone.Theaccuracy of these devices is adequate for the usual measurement of air-flow in HVAC systems.A suitable light duty substitute cone can befabricated of artists beadboard with taped seams, about 24" square atlarge end and 12" square at small end by about 36" long, and with ve-locity readings made using Pitot tube or anemometer in the small end.Hot Wire AnemometersAnemometers using the hot-wire principle are available in velocityranges from zero to over 6,000 feet per minute.The instruments arefairly expensive but are available in a broad range of costs with the costvarying with the ability of the instrument to measure velocity and tem-perature.These devices are necessary when measuring velocities belowabout 100 feet per minute in order to achieve reasonable accuracy.Thesensor can be mounted on a wand with a curly-cord for getting to hard-to-reach points.Some models can read temperature by means of aswitch on the meter box. TOOLS AND FIXTURES FOR ATC SYSTEMS OPERATION & MAINTENANCE 249Rotating Vane AnemometersThe old standby rotating vane anemometer (Figure 13-10) is fairlyinexpensive and simple to use.For accurate measurements, the readingsmust be corrected from the calibration chart furnished with the meterand the meter should be recalibrated periodically to provide a currentcalibration chart.Deflecting Vane AnemometersA deflecting vane anemometer (Figure 13-11) is not as accurate asother types of anemometers but is accurate enough for performing rou-tine airflow measurements in HVAC systems.Models are available inthe $100 range.HYDRONIC SYSTEM TESTING ANDBALANCING INSTRUMENTSFlow SensorsThese devices (Figure 13-12), frequently called by the trade name Annubar, are very useful for measuring flow in piping using differen-tial pressure gauges, u-tube manometers, or permanent flow meters.Theflow sensors are similar toPitot tubes with doublepressure chambers con-tained in a stainless steeltube inserted into the pip-ing through a half-couplingor saddle welded to thepiping.Sensors are avail-able for a range of pipesizes from 2" to 42".Forsizes 1/2" through 2" pipesize, a nipple-mounted sen-sor is available.BecauseFigure 13-10.RotatingVane Anemometer.(Cour-tesy Davis Instruments.) 250 HVAC CONTROLS OPERATION & MAINTENANCEthese devices can usually be installedin less than 30 minutes, they are cost-effective in retrofit applications aswell as new construction.Pressure and TemperatureTesting PortsThese devices (Figure 13-13),frequently called Pete s Plugs, arevery useful for getting access to pip-ing systems to measure temperatureand pressure.They are nicely ma-chined devices with a high-tempera-ture polymer plastic seal, similar to afootball bladder valve, in a bodythreaded for 1/2" pipe thread andwith a hex-head gasketed cap overthe seal.Test ports can be installed oncopper, plastic, or steel piping sys-tems by drilling and tapping an open-Figure 13-11.Deflectinging in the pipe wall or by welding aVane Anemometer.(Cour-half-coupling to steel pipe, then bor-tesy Dwyer Instruments,ing an opening in the pipe wall andInc.)mounting the device in the coupling.Pressure gauges and thermometers are available with about 3/32" diam-eter stems for use with the ports, but the dials on these instruments aretoo small to give accurate readings
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