300-R010-45G Datasheet, PDF (4/36 Pages) Magnetrol International, Inc. – Echotel® Model 300/301 Ultrasonic Non-Contact Transmitter For Level/Volume/Open Channel Flow

MEASUREMENT RANGE CALCULATIONS, cont.
Operating Parameter
Condition
Performance
Multiplier ^Application
Smooth, glasslike surface
1.0
SURFACE AGITATION: Surface agitation or waves can degrade the
performance. Moderate agitation results in only slight degradation
Slight agitation, choppiness
0.9
of performance. The worst case is when the surface is a good
Heavy agitation
0.8
reflector, but in the wrong direction. (See also transducer alignment.) _{Slight vortex (6°)}
0.7
VAPORS AND STEAM: Vapors in the air space, above the process,
become apparent, and cause problems when the liquid process
No condensation
1.0
temperature is well above the temperature of the airspace. The
greater the difference, the more expected vapor problems. The
problems result from condensation or layering in the sound path,
both of which attenuate the sound signal, degrading performance.
Little condensation
0.9
Avoid steam if possible.
To avoid these problems, ensure that the vessel is insulated so that
vapors are less likely to condense. If a vent is used, be sure that the ^{Much condensation/}
vent, which is where condensation will form, is well away from the
foggy appearance
0.8
transducer.
BEAM SPREAD INTERFERENCE: It is strongly recommended that
nothing be allowed within the transducer’s beam, except the liquid
which is being monitored. Often, the signal from the liquid will be
strong, compared to the signal from other sources, such as ladder
rungs, filling process material, support struts, etc. For that reason,
some applications may provide satisfactory results, even with
interference. Interference from agitator blades is only an intermittent
interference that usually has little effect on performance.
It is recommended there be no interference within the 6° half angle
of the transducer beam. If interference is unavoidable, make the inter-
ference as far as possible from the transducer so that the real signal
at the longest distance is stronger than the interference signal.
No interference
Agitator at speed less than 60 RPM
Agitator at speed greater than 60 RPM
Interference outside 4°, far from
transducer (in bottom third of range)
Interference outside 4°, near to
transducer (in top third of range)
1.0
1.0
Consult
Factory
0.8
0.5
TRANSDUCER ALIGNMENT: Optimum performance is obtained when
the transducer is perfectly aligned. If the process is not perpendicular
Beam perpendicular to liquid surface
1.0
to the sound beam, the sound will not reflect properly back to the
transducer. The effect is significant.
Beam 4° off from perpendicular
0.5
FOAM: Even small thicknesses of foam can attenuate the ultrasound No foam
1.0
and render the system inoperative. If possible, moving the transducer
to an area in the tank where there is less foam will improve the
Light froth, less than 0.25" thick
0.8
performance. Thick, heavy-density foams can sometimes produce
Light foam, less than 0.5" thick
0.5
a reflection from the top of the foam. The multipliers shown at right
are general guidelines. For further assistance consult the factory.
Light foam, more than 1" thick
0.1
No dust
1.0
DUST: Dust attenuates the sound and results in poor performance.
Haze, barely perceptible
0.7
Even barely perceptible haze in the air can cause significant
attenuation.
Slight dust
0.4
Heavy dust
0.1
AIR MOVEMENT: The movement of air, as possible in an open top
No air movement
1.0
vessel, can create a layer from which the sound will reflect. This will
be most noticeable in applications where vapors or steam tend to
Open vessel, but transducer below rim
0.8
form.
Open air movement in sound path
0.7
AMBIENT TEMPERATURE: The ambient temperature can have a
-20° to +140° F (-29° to +50° C)
1.0
significant effect on the sound and on the transducer’s capability to
transmit and receive sound. The most noticeable effect on the
-40° to -20° F (-40° to -29° C)
0.9
transducer is at the temperature extremes.
+140° to +160° F (+50 to +70° C)
0.9
PRESSURE: Sound requires air molecules to be able to travel. Sound
will not travel in a vacuum. Likewise, higher pressures will allow
the sound to continue without decay, which can cause problems with
multiple echoes.
-10 to +50 psig (0.689 to +3.45 Bar)
Pressures outside above rating
1.0
Consult
Factory
Multiply all values together in the application column
Maximum Potential Range for Model 300/301 X 30'
Maximum allowable measurement range for this application
4