Thermo MeasureTech 1440 Microwave Level Gauge User Manual 95

Thermo MeasureTech Microwave Level Gauge 95

Users Manual

1Accu-Wave Level GaugeInstallation Instructions - DraftIntroductionThe Accu-Wave Model 1440 Radar Level Gauge uses a microwave signal tocontinuously measure the level of the process material. The transmitted microwavesignal is reflected off of the surface of the process material. The Digital SignalProcessing (DSP) software detects this reflection or echo and computes thedistance to the liquid or solid material in the tank. The Accu-Wave firmware thenuses the distance measurement to calculate level, volume, and other user-selectedmeasurements.The Accu-Wave Radar Level Gauge consists of an integrated sensor andtransmitter. The microwave and transmitter circuitry are combined on a singleboard. Initially, the Accu-Wave will be available with dielectric rod antennas(probes). Horn antennas will be provided as a future option.AntennasThe standard antenna configuration for the Accu-Wave gauge consists of adielectric-filled, 1 inch O.D. stainless steel waveguide with a dielectric rodantenna. Polypropylene or Teflon (PTFE) antennas are available. The stainlesssteel (SS 316) waveguide material is swaged (crimped) over the dielectric-fillmaterial. The swage serves both as a process seal as well as a pressure seal.Future options for the dielectric rod antennas will include Hastelloy waveguidesand a fully-jacketed configuration where the only material exposed to the processwill be Teflon (PFA).In addition, horn antennas will be available in the future, with horn diametersranging from 2 to 8 inches. For the horn antenna configuration, all materialsexposed to the process are constructed of stainless steel (SS 316) and Teflon.Mounting ConfigurationsThe dielectric rod antennas are fitted with a 1-inch NPT threaded bushing, weldedto the waveguide. Flanges are also available – 150 lb. or 300 lb., with diametersranging from 2 to 8 inches. The waveguides are available in 6, 9, 12, or 15 inchlengths, where the length refers to the portion of the waveguide that extends belowthe bushing or the flange. For optimum performance the end of the waveguideshould reach to the bottom of the nozzle. Level measurements can be made withthe process material above the antenna to within ~3.5 inches of the antennawaveguide; however; measurement accuracy will be degraded.Horn antennas are provided with welded flanges.
2CommunicationsRS-485 and RS-232 (optional) serial ports are provided to supportcommunications with the gauge via a remote terminal, a PC with terminalemulation software, or a TN Technologies' Hand Held Terminal.Current OutputThe gauge provides a 4-20 mA, loop-powered (24 Vdc) current output.Setting Up and Using the GaugeThe companion manual “Accu-Wave Operation Manual” (717791) providesdetailed information on how to set up the Accu-Wave software and operate theAccu-Wave gauge.Hardware InstallationLicensingAll microwave frequency tuning is completed at the factory (TN TechnologiesInc., Round Rock, Texas). The Accu-Wave gauge has a Part 15 FCC license(approval pending) for metal tank installations, so no special license is required.For other installations, a Part 90 FCC license must be obtained and displayed atthe installation site. TN Technologies can assist you with licensing. For assistance,call or fax one of the following numbers:• Phone: (800) 736-0801 (US only)• Main Office: (512) 388-9100• FAX: (512) 388-9200Selecting a Location for the GaugeSelecting a good location and properly mounting the gauge will help ensure theaccuracy and ease of operation of the gauge.Follow these guidelines when selecting a location:1. The operating temperature range for the electronics is –40ΟC to 70ΟC(–40ΟF to 158ΟF).2. The antenna (probe) should be mounted above the smoothest portionof the process material surface. The antenna should be mounted with3 degrees of vertical.3. For best performance, there should be a clear path between theantenna and the process material to avoid false reflections. Verify thatthe path is clear of pipes, beams, or any intermittent liquid sprays thatcould block the microwave beam. Try to locate the sensor to keep thebeam path (approximately 18º wide) clear of the following conditions:
3• Turbulence, splashing, or waves such as those caused by filling,recirculation, or sparging of light material entrances near thebottom of the tank.• Pipe entrances near the top or side of the tank.• Agitator blade passing directly through the beam path.• Vortices caused by baffles, drains, or any other obstructions.4. The mounting location should also avoid horizontal structuralsurfaces such as baffle support brackets or side wall joints as thesesurfaces reflect a strong false signal.5. If the vessel has a dome top, a good guideline is to mount the sensoraway from the vessel’s center point by at least 10% of the vesseldiameter.Note: If the sensor is mounted in the center of the vessel, the dome topwill act as a parabolic antenna, potentially enhancing “false”echoes due to multiple reflections of the transmitted energy.The tank’s nozzle must meet the following requirements.1. For dielectric rod antennas, the antenna waveguide should extend to orbelow the bottom of the nozzle.2. Nozzle must meet or exceed tank pressure requirements.3. Align nozzle within 3º of vertical (verify this with a carpenter’scombination level). Flange surface must be aligned within 3º ofhorizontal (verify this with a carpenter’s combination level).Note: Refer to the equipment tag for the approvals applicable to theconfiguration of your Accu-Wave gauge.Dimensional DrawingsRefer to the proper dimensional drawings for the mounting dimensions.Note: Reduced-size copies of the drawings are provided for yourconvenience.Mounting HardwareFor flange configurations, the following customer-supplied hardware is required:1. 1 gasket suitable for the process material2. 16 steel washers3. 8 nuts and bolts• 150 lb flange (5/8 inch) hardware• 300 lb flange (3/4 inch) hardware Caution: Use proper lifting procedures to avoid injury.
4 Install the bolts and washers, and attach the nuts. Tighten the bolts in a star–patterned sequence to equalize compression. Unless otherwise specified, use atorque specification of 50 foot pounds. For 1 inch, NPT bushing configurations, simply thread the bushing into thecorresponding opening on the tank. To adapt to a flange mounting, simply use atapped flange that will accept the 1 inch NPT bushing. Installation Wiring Basic wiring consists of• connecting power to the gauge (24 Vdc standard, 100-240 Vac futureoption), and• setting up serial communications with the gauge. Additional wiring can include• relay contacts,• contact switch inputs, and• 4-20 mA current outputs.Caution: Remove all power from the unit before making anyconnections.Warning: All wiring must be done by qualified individuals inaccordance with NEC (National Electric Code) ANSI/NFPA 70specifications, or the Canadian Electrical Code, Part I.If metal conduit is used, it must be grounded.InstructionsYou will need a 1/8 inch bladed screwdriver to connect the wires to the plug-inconnector. Refer to Wiring Diagram 868641 for wiring details.

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