Operating Manual

Accu-Wave Chapter 1 Introduction
TN Technologies 1-1
Chapter 1 Introduction
The Accu-Wave Model 1440 Radar Level Gauge uses a microwave signal to continuously
measure the level of the process material. The Accu-Wave can often provide better
performance than sonic measurement systems, particularly in hostile environments,
because the microwave signal is unaffected by mist, surface agitation, temperature
changes, or pressure changes. The menu-driven user interface, with built–in help screens,
is designed to make the gauge easy to set up and operate.
The Accu-Wave transmits a microwave signal that is reflected from the surface of the
process material. The reflected signal or echo is received by the Accu-Wave. The Digital
Signal Processing (DSP) software detects the echo and computes the distance to the liquid
or solid material in the tank. The Accu-Wave firmware uses the distance measurement to
calculate level, volume, and other user-selected measurements.
Description
The Accu-Wave Radar Level gauge consists of an integrated sensor and transmitter with
the microwave sensor and transmitter circuitry combined on a single electronics board. The
microwave signal is launched from the bottom of the board via the cup/probe assembly
into the antenna (or probe). The antenna serves to focus the transmitted signal as well as to
receive the reflected echo. Currently, the Accu-Wave is available with dielectric rod
antennas (probes). Horn antennas will be available 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. The dielectric
rod antenna is available in either polypropylene or Teflon (PTFE). 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. The PTFE antenna design also
uses o-rings to ensure the integrity of the process seal at low temperatures. Both Viton and
Kalrez o-rings are available.
Horn antennas will be as a future option, with diameters ranging from 2 to 8 inches.
Mounting Configurations
The dielectric rod antennas are fitted with a 1-inch NPT threaded bushing, welded to the
waveguide. Welded flanges are also available – 150 lb. or 300 lb., with diameters ranging
from 2 to 8 inches. 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 continue to be made as the level of the process material rise
above the bottom of the antenna to within ~3.5 inches of the bottom of the waveguide.