Thermo MeasureTech 1440 Microwave Level Gauge User Manual 95

Thermo MeasureTech Microwave Level Gauge 95

Users Manual

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Accu-Wave Level Gauge
Installation Instructions - Draft
Introduction
The Accu-Wave Model 1440 Radar Level Gauge uses a microwave signal to
continuously measure the level of the process material. The transmitted microwave
signal is reflected off of the surface of the process material. The Digital Signal
Processing (DSP) software detects this reflection or echo and computes the
distance to the liquid or solid material in the tank. The Accu-Wave firmware then
uses the distance measurement to calculate level, volume, and other user-selected
measurements.
The Accu-Wave Radar Level Gauge consists of an integrated sensor and
transmitter. The microwave and transmitter circuitry are combined on a single
board. Initially, the Accu-Wave will be available with dielectric rod antennas
(probes). Horn antennas will be provided as a future option.
Antennas
The standard antenna configuration for the Accu-Wave gauge consists of a
dielectric-filled, 1 inch O.D. stainless steel waveguide with a dielectric rod
antenna. Polypropylene or Teflon (PTFE) antennas are available. The stainless
steel (SS 316) waveguide material is swaged (crimped) over the dielectric-fill
material. The swage serves both as a process seal as well as a pressure seal.
Future options for the dielectric rod antennas will include Hastelloy waveguides
and a fully-jacketed configuration where the only material exposed to the process
will be Teflon (PFA).
In addition, horn antennas will be available in the future, with horn diameters
ranging from 2 to 8 inches. For the horn antenna configuration, all materials
exposed to the process are constructed of stainless steel (SS 316) and Teflon.
Mounting Configurations
The dielectric rod antennas are fitted with a 1-inch NPT threaded bushing, welded
to the waveguide. Flanges are also available – 150 lb. or 300 lb., with diameters
ranging from 2 to 8 inches. The waveguides are available in 6, 9, 12, or 15 inch
lengths, where the length refers to the portion of the waveguide that extends below
the bushing or the flange. For optimum performance the end of the waveguide
should reach to the bottom of the nozzle. Level measurements can be made with
the process material above the antenna to within ~3.5 inches of the antenna
waveguide; however; measurement accuracy will be degraded.
Horn antennas are provided with welded flanges.
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Communications
RS-485 and RS-232 (optional) serial ports are provided to support
communications with the gauge via a remote terminal, a PC with terminal
emulation software, or a TN Technologies' Hand Held Terminal.
Current Output
The gauge provides a 4-20 mA, loop-powered (24 Vdc) current output.
Setting Up and Using the Gauge
The companion manual “Accu-Wave Operation Manual” (717791) provides
detailed information on how to set up the Accu-Wave software and operate the
Accu-Wave gauge.
Hardware Installation
Licensing
All microwave frequency tuning is completed at the factory (TN Technologies
Inc., 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 at
the 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) 388-9200
Selecting a Location for the Gauge
Selecting a good location and properly mounting the gauge will help ensure the
accuracy 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 portion
of the process material surface. The antenna should be mounted with
3 degrees of vertical.
3. For best performance, there should be a clear path between the
antenna and the process material to avoid false reflections. Verify that
the path is clear of pipes, beams, or any intermittent liquid sprays that
could block the microwave beam. Try to locate the sensor to keep the
beam path (approximately 18º wide) clear of the following conditions:
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• Turbulence, splashing, or waves such as those caused by filling,
recirculation, or sparging of light material entrances near the
bottom 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 structural
surfaces such as baffle support brackets or side wall joints as these
surfaces reflect a strong false signal.
5. If the vessel has a dome top, a good guideline is to mount the sensor
away from the vessel’s center point by at least 10% of the vessel
diameter.
Note: If the sensor is mounted in the center of the vessel, the dome top
will 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 or
below 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’s
combination level). Flange surface must be aligned within 3º of
horizontal (verify this with a carpenter’s combination level).
Note: Refer to the equipment tag for the approvals applicable to the
configuration of your Accu-Wave gauge.
Dimensional Drawings
Refer to the proper dimensional drawings for the mounting dimensions.
Note: Reduced-size copies of the drawings are provided for your
convenience.
Mounting Hardware
For flange configurations, the following customer-supplied hardware is required:
1. 1 gasket suitable for the process material
2. 16 steel washers
3. 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.
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Install the bolts and washers, and attach the nuts. Tighten the bolts in a star–
patterned sequence to equalize compression. Unless otherwise specified, use a
torque specification of 50 foot pounds.
For 1 inch, NPT bushing configurations, simply thread the bushing into the
corresponding opening on the tank. To adapt to a flange mounting, simply use a
tapped 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 future
option), 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 any
connections.
Warning: All wiring must be done by qualified individuals in
accordance with NEC (National Electric Code) ANSI/NFPA 70
specifications, or the Canadian Electrical Code, Part I.
If metal conduit is used, it must be grounded.
Instructions
You will need a 1/8 inch bladed screwdriver to connect the wires to the plug-in
connector. Refer to Wiring Diagram 868641 for wiring details.

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