Eclipse
®
Enhanced Model 705
Guided Wave Radar
Level Transmitter
D E S C R I P T I O N
The Enhanced Eclipse Model 705 Transmitter is a loop-
powered, 24 VDC liquid-level transmitter based on the
revolutionary Guided Wave Radar (GWR) technology.
Encompassing a number of significant engineering
accomplishments, this leading-edge level transmitter is
designed to provide measurement performance well
beyond that of many traditional technologies, as well as
“through-air” radar.
The innovative enclosure is a first in the industry, orient-
ing dual compartments (wiring and electronics) in the
same plane, and angled to maximize ease of wiring, con-
figuration, and data display.
One universal transmitter can be used with all probe
types and offers enhanced reliability for use in SIL 2
hardware systems.
Eclipse supports the FDT/DTM standard and, with the
PACTware
™
Frame Program, allows for additional config-
uration and trending flexibility.
Measures Level, Volume, and Interface
SIL 2
F E A T U R E S
•
“T
RUE
L
EVEL
” measurement—not affected by media
characteristics (e.g., dielectrics, pressure, density, pH,
viscosity, etc.)
•
Two-wire, 24 VDC loop-powered transmitter for
level, interface, or volume.
•
20-point custom strapping table for volumetric
output.
•
360° rotatable housing can be dismantled without
depressurizing the vessel.
•
Two-line, 8-character LCD and 3-button keypad.
•
Probe designs: up to +800° F / 6250 psi (+430° C /
430 bar).
•
Saturated steam applications up to 2250 psi @
+650° F (155 bar @ +345° C).
•
Cryogenic applications down to -320° F (-196° C).
•
Integral or remote electronics (up to 12 feet (3.6 m)).
•
Suited for SIL 1 or SIL 2 Loops (full FMEDA report
available).
A P P L I C A T I O N S
MEDIA:
Liquids or slurries; hydrocarbons to water-based
media (dielectric 1.4 - 100).
VESSELS:
Most process or storage vessels up to rated
probe temperature and pressure.
CONDITIONS:
All level measurement and control appli-
cations including process conditions exhibiting visible
vapors, foam, surface agitation, bubbling or boiling, high
fill/empty rates, low level and varying dielectric media or
specific gravity.
Download your free copy of the Eclipse 705 performance
reports by WIB/Evaluation International (SIREP)/EXERA
from magnetrol.com.
T E C H N O L O G Y
OVERALL
LEVEL
Eclipse Guided Wave Radar is based upon the technolo-
gy of TDR (Time Domain Reflectometry). TDR utilizes
pulses of electromagnetic energy transmitted down a
wave guide (probe). When a pulse reaches a liquid sur-
face that has a higher dielectric constant than the air (
ε
r
of 1) in which it is traveling, the pulse is reflected. The
transit time of the pulse is then measured via ultra speed
timing circuitry that provides an accurate measure of the
liquid level.
INTERFACE
LEVEL
Initial
Pulse
Reflected
Pulse
Air
ε
r
= 1
Liquid
ε
r
> 1.4
for coaxial probes
Transmitted
Pulse
The Eclipse Model 705 is capable of measuring both an
upper liquid level and an interface liquid level. Even after
the pulse is reflected from the upper surface, some of the
energy continues down the GWR probe through the
upper liquid. The pulse is again reflected when it reach-
es the higher dielectric lower liquid. It is required that the
upper liquid has a dielectric constant between 1.4 and 5,
and the lower liquid has a dielectric constant greater than
15. A typical application would be oil over water, with
the upper layer of oil being non-conductive (
ε
r
≈
2.0),
and the lower layer of water being very conductive
(
ε
r
≈
80). The thickness of the upper layer must be > 2"
(50 mm). The maximum upper layer is limited to the
length of the GWR probe, which is available in lengths
up to 40 feet (12 meters).
EMULSION
LAYERS
Overall Liquid Level
Reference
signal
Air
ε
r
= 1
Upper level
signal
> 2"
(50 mm)
Interface
level signal
Low dielectric medium
(eg. oil,
ε
r
= 2)
< 2" (50 mm)
high dielectric medium
(eg. water,
ε
r
= 80)
As emulsion layers can decrease the strength of the
reflected signal, the Eclipse Model 705 should only be
utilized in those interface applications that have clean,
distinct layers. Contact factory for application assistance.
Time
Interface Level
Reflected
Pulse
Air
ε
r
= 1
Initial
Pulse
ε
r
> 1.9 for twin
flexible probes
Transmitted
Pulse
Bulk Solid Level
2
P R O B E
O V E R V I E W
Choosing the proper Guided Wave Radar (GWR) probe is the most important decision in the application process. The
probe configuration establishes fundamental performance characteristics. Coaxial, twin element (rod or cable) and sin-
gle element (rod or cable) are the three basic configurations used today; each with specific strengths and weaknesses.
COAXIAL
PROBES
The Coaxial probe is the most efficient of all probe configurations
and should be the first consideration in all applications. Analogous
to the efficiency of modern, coaxial cable, coaxial probes allow
almost unimpeded movement of the high frequency pulses
throughout its length.
The electromagnetic field that develops between the inner rod and
outer tube is completely contained. See Figure 1. The efficiency
and sensitivity of a coaxial configuration yields robust signal
strength even in extremely low dielectric (
ε
r
≥1.4)
applications.
The sensitivity of this “closed” design, however, also makes it more
susceptible to measurement error in applications of coating and
Figure 1
Coaxial Probe
buildup.
TWIN ROD PROBES
The relationship of the Twin Rod probe to a Coaxial is similar to
that of older, twin-lead, antenna lead-in to modern, coaxial cable.
300 ohm twin-lead cable simply does not have the efficiency of
75-ohm coax. The parallel conductor design is less sensitive than
the concentric coaxial. See Figure 2. This translates to Twin Rod
GWR probes measuring dielectrics of only
ε
r
≥1.9.
The “open” design also allows more accurate measurement where
coating/buildup are possible. A film coating has little effect on per-
formance. However, bridging of material between the rods or
buildup on the spacers can cause improper measurement and
should be avoided. Figure 2 also shows that the electromagnetic
field develops not only between the rods, it also expands outward
making it more sensitive to proximity effects of objects located
immediately around it.
Figure 2
Twin Rod Probe
3
P R O B E
SINGLE
O V E R V I E W
PROBES
ROD
Single element GWR probes act quite differently from Coaxial and
Twin element designs. The pulses of energy develop between the
center rod and the mounting nut or flange; the pulse propagates
down the rod as it references its ground at the top of the tank. The
efficiency of the pulse “launch” is directly related to how much
metallic surface exists around it at the top of the vessel.
Figure 3 shows the single element design and how the pulse
expands into a teardrop shape as it propagates away from the top
of the tank (ground reference). This Single element configuration
is the least efficient of the three with minimum dielectric detection
approximately
ε
r > 10. This dielectric performance improves con-
siderably (
ε
r > 1.9) when the probe is installed between 2–6"
(50–150 mm) of a metal tank wall or in a cage/bridle. Because the
design is the “open”, it exhibits two strong tendencies. First, it is
the most forgiving of coating and buildup. (The PFA-insulated
probe is the best choice for severe coating). Secondly, it is most
affected by proximity issues. It is important to note that a parallel
metal wall INCREASES its performance while a singular, metal
object protruding near the probe may be improperly detected as a
liquid level.
Figure 3
Single Rod Probe
H Y G I E N I C
M O D E L
7 0 5
Eclipse 705 is available with a deep drawn housing and a 0.4 µm
(RA 15) finished single rod GWR probe for use in ultra clean envi-
ronments.
For more details – refer to bulletin 57-110.
3
⁄
4
" Hygienic Connection without bend
1
1
⁄
2
" Hygienic Connection with bend
316 SS probes can be bent to avoid internal obstructions
such as agitator blades and spray balls, and to insure
lowest possible level detection.
0.25 inch diameter probes suitable for use in smaller
vessels where space is at a premium. Available in
lengths up to 72 inches.
4
S E L E C T I O N
COAXIAL TYPE GWR PROBE
G U I D E
TWIN ROD/CABLE TYPE GWR PROBE
SINGLE ROD/CABLE TYPE
signal propagation
signal propagation
signal propagation
end view
end view
Application
Dielectric
Limit
Temperature
Limits
Pressure
Vacuum
Applications
Overfill Safe
Foam
GWR
Probe
Coaxial GWR Probes:
Maximum Viscosity 500 cP (I.D.
3
⁄
4
") – 1500 cP (I.D. 1
3
⁄
4
")
Level
High Temp./High Pressure
Level/Interface
ε
r
1.4–100
ε
r
1.4–100
ε
r
1.9–100
ε
r
1.9–100
ε
r
1.9–100
ε
r
1.9–100
ε
r
1.9–100
ε
r
1.9–100
ε
r
4–100
ε
r
10–100
ε
r
1.4–100
-40° to +400° F max 1015 psig
(-40° to +200° C)
(70 bar)
-321° to 800° F max 6250 psig
(-196° to +430° C)
(430 bar)
up to +650° F
(up to +345° C)
max 2250 psig
(155 bar)
Yes
Full
Yes
Yes
Yes
Yes
No
Yes
No
No
No
No
7xR
7xM
7xD
7xL
7xS
7xT
7xN
Saturated Steam
Interface
-40° to +400° F max 1015 psig
(-40° to +200° C)
(70 bar)
Twin Rod/Cable GWR Probes:
Maximum Viscosity 1500 cP
-40° to +400° F max 1000 psig
(-40° to +200° C)
(70 bar)
-40° to +400° F max 1000 psig
(-40° to +200° C)
(70 bar)
Ambient
Atmospheric
Yes
Yes
Yes
No
No
No
Yes
No
n/a
7xB
7x7
7x5
Liquids – Rod
Liquids – Cable
(level/interface)
Solids – Cable
Single Rod/Cable GWR Probes:
Maximum Viscosity 10,000 cP
-40° to +300° F max 1000 psig
(-40° to +150° C)
(70 bar)
-40° to +300° F max 1000 psig
(-40° to +150° C)
(70 bar)
Ambient
Atmospheric
Yes
Yes
Yes
Yes
No
No
No
No
Yes
Yes
n/a
Yes
7xF
7x1
7x2
7xJ
Liquids – Rod
Liquids – Cable
Solids – Cable
High Temp./
High Pressure
Each Eclipse probe can be used for vacuum service (negative pressure) but only the Borosilicate
Eclipse is ideally suited to be used on foaming applications but in specific conditions where dense
GWR probes (7xD/7xL) are suited for full vacuum conditions (Helium leak < 10
-8
cc/s @ 1 bar abs.)
foam can enter in the stilling well, coaxial GWR probes are not recommended.
-40° to +600° F max 3002 psig
(-40° to +315° C)
(207 bar)
Depends on the spacer material. See model selection 7xD/7xL GWR probe.
For media with
ε
r 1.9 to 10, GWR probe must be mounted between 3" and 6" (75 and 150 mm)
away from the metal tank wall or in a metal cage/stillwell.
5
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