E C H O T E L
®
C O N TA C T
U LT R A S O U N D
Contact Ultrasonic Level Sensing
FROM
U
ltrasound technology was developed during
WWII under the acronym
SONAR
(SOund
Navigation And Ranging). First applied to
the amplifier becomes as oscillator causing a relay
circuit in the electronics to indicate a wet gap
returns to an idle state.
condition. When liquid vacates the gap, the amplifier
Pulsed-signal
Models 940/941
and
961/962
feature
a digital electronic amplifier
which produces a powerful
pulse of ultrasonic energy five
continuous wave units. This
pulsed-signal technology will
measurement to this day.
ment continues to play a significant role in liquid level
Ultrasonic instruments are made
process control in the 1960s, ultrasonic level measure-
for both contact and non-contact
(or through-air) level sensing. This
of contact ultrasonic products that
provide single and dual point liq-
virtually every process industry.
uid level measurement in
brochure focuses on the Echotel
®
line
to ten times stronger than most
provide more accurate measure-
ment in conditions of aeration,
suspended solids, turbulence,
and highly viscous liquids.
high-frequency ultrasonic
signal units generates pulses of
Continuous-Wave and
Pulsed-Signal Sensing
The transmit crystal of pulse-
is achieved by either continuous-
switch uses two piezoelectric
Ultrasonic contact level sensing
Challenging process conditions such as
suspended solids or aeration are best
managed with pulsed-signal technology.
Models 961/962 switches further minimize
the effects of mild turbulence or splashing
with adjustable time delays.
wave or pulsed-signal technology.
Our
Model 910
continuous-wave
other across the transducer gap.
crystals positioned opposite each
duration. In between each pulse
in the gap the receive crystal
energy only milliseconds in
transmission. If liquid is present
detects the pulse and reports a
the receive crystal “listens” for the
The transmit crystal generates an acoustical signal
signal. When liquid is present in the transducer gap,
which the receive crystal converts into an electrical
with air, the receive crystal cannot detect the pulse, and
reports a dry gap condition.
wet gap condition to the electronics. When the gap is filled
T
2
R
Contact ultrasonic level switches
use ceramic discs called piezo-
electric crystals to transmit and
receive ultrasonic energy. A
transmit crystal (T) is positioned
on one side of a transducer gap
and a receive crystal (R) is posi-
tioned on the opposite side. Tip-
sensitive style gaps—the only
style used on Echotel
®
switches—
can sense level to within
1
⁄
4
" from
the end of the transducer.
25+ Years of Ultrasonic Measurement Solutions for Industrial Process
Application Guidelines
brand a world leader in liquid level switches.
required, our economical
Model 910
with
with a tip-sensitive transducer.
• For applications where self-test isn’t
switch technology has made the ECHOTEL
Over 25 years of experience with ultrasonic gap
makes them suitable for use in Safety Integrity Level
(SIL) 2 loops. Having either relay output or mA current
shift capability, Models 961/962 can be used for more
process applications, making them the most universal
liquid level switches available today.
Today’s line offers three distinct product offerings:
continuous wave technology is a reliable switch
940/941
offer both advanced tip-sensitive
• Though OEM priced, our compact
Models
910
Advantages and Limitations
ultrasonic technologies are:
The advantages of contact level sensing using
• Low cost single and dual point sensing.
transducers and pulsed signal technology.
• Accurate and reliable in a wide variety of liquids.
• A broad range of available sensor materials.
dielectric or temperature shifts.
delay feature.
signal technology, advanced self-test and a time
Models 961/962 represent the pinnacle of
Model 962
offer tip-sensitive transducers, pulsed
940/941
• Single Point
Model 961
and Dual Point
• Easy installation and simple configuration.
• Unlike tuning forks, no density adjustments required.
• Transmits a stable signal despite liquid property
• Switches are 100% electronic and
ELECTRO
changes in specific gravity, conductivity, pH, and
•
10
0
transducer, piezoelectric crystals, and testing
for electromagnetic noise, alarms the user of a
degrade or require high maintenance.
MO
VIN
G
curtail nuisance alarms and relay chattering.
An adjustable time delay of 0.5 to 45 seconds helps
With extensive FM, CSA, and ATEX approvals
malfunction or the presence of EMI/RFI noise.
961
ultrasonic signal. These conditions include:
• Extreme aeration of the liquid.
Certain process conditions may interfere with the
• Slurries with a very high percentage of solids.
• Very aggressive turbulence and splashing.
• Liquids which generate crystallized coatings.
hazardous location. Their SFF* value of over 90%
the Models 961/962 are suitable for virtually any
At a Glance:
Model
910
940
941
961
962
Ultrasonic Technology
Continuous Wave
Pulsed Signal
Pulsed Signal
Pulsed Signal
Pulsed Signal
Contact Ultrasonic Switches
Set Points
Single
Single
Single
Single
Dual
Output
Relay
Relay
Current Shift (CS)
Relay or CS
Relay or CS
Mounting
Integral
Integral
Integral
Integral or Remote
Integral or Remote
SIL Loop 3-A
N.A.
2
1
2
2
I
I
I
Self-Test Time Delay
I
I
Models 940 and 961/962 SFF values are over 90%, which allows them to be used in SIL
2
loops.
*
In the language of Safety Instrumented Systems (SIS), Safe Failure Fraction (SFF) indicates all safe and dangerous detected failures. The
A
P
RT
S
ultrasonic switch development at Magnetrol
®
.
Their continuous self-testing of electronics,
%
C•
NI
contain no moving parts which can
ZER
O
3
910
Model 910
Level Switch
A reliable switch featuring a 10 amp DPDT gold
flash relay field-selectable for high or low level fail-
safe. Worldwide safety approvals, 2-year warranty.
Proximity Sensing
The
Model 910
features a tip-sensitive
transducer which measures liquid level
to within 0.25" (6 mm) from the end of its
transducer. When used as a low level switch,
it can measure level further down into a tank
or vessel.
Omni-Directional Mounting
Model 910 may be mounted horizontally or
vertically. Mounting options include NPT
and BSP threaded, flanges and sanitary
connections.
Worldwide Safety Approvals
With FM, CSA and ATEX approvals on one
agency nameplate, this is the perfect switch
for OEM applications with global customer
destinations.
Model 910 Electrical Specifications
Power Supply:
120 VAC (+10%/-15%), 50/60 Hz
240 VAC (+10%/-15%), 50/60 Hz
24 VDC (±10%)
Power Consumption:
Relay Output:
Gold Flash:
Hermetically-Sealed:
Repeatability:
Fail-Safe:
Ambient Temperature:
Electronics:
Process Temperature:
Transducer:
Operating Pressure:
-40° to +250° F (-40° to +121° C)
800 psig (55 bar) maximum
-40° to +160° F (-40° to +71° C)
DPDT, 10 amps @ 120 VAC,
240 VAC, or 24 VDC
DPDT, 5 amps @ 120 VAC,
240 VAC, 24 VDC
0.078" (2 mm)
Field selectable high or low
2.5 VA nominal
Liquid Level Applications
PROCESS MEDIA:
• Clean liquids
• Low viscosity liquids
• Liquids with low % solids
• Corrosive liquids
OF SPECIAL INTEREST TO:
• Water and Wastewater Treatment
• Foods, Beverages, Pharmaceuticals
• Oil and Gas Industries
• OEM and Skid Manufacturers
4
940/941
High-Performance Ultrasound
3/4” NPT
Fitting
Tri-Clamp
Fitting
Level Switches
Economical, very compact switches with pulsed
signal technology and tip-sensitive transducers.
High cost-benefit ratio for OEM switch users.
Pulsed signal technology excels in difficult
conditions that may cause other ultrasonic
switches to falter. This technology also provides
excellent immunity from electrical noise that is
common in many industrial applications.
Choice of Electronics
Model 940 Relay Version
offers a 1 amp
SPDT relay output.
ANSI
Fitting
Model 941 Current-Shift Version
offers a mA
current shift output.
Suitable for SIL Loops
Safety Integrity Level (SIL) data is available for
the 940/941 switches in the form of a Failure
Modes, Effects and Diagnostic Analysis
(FMEDA) report. The Model 940 is suitable
for use in SIL 2 loops, and the Model 941 is
suitable for use in SIL 1 loops.
Model 940/941 Specifications
Power Supply:
Power Consumption:
Signal Output (940):
Signal Output (941):
Cabling:
Repeatability:
Response Time:
Ambient Temperature:
Process Temperature:
Maximum Pressure:
Ingress Protection:
Shock:
Vibration:
12 to 35 VDC
Less than 1 Watt
SPDT relay, 1 amp @ 30 VDC, 0.5
amp@125 VDC, 0.5 amp @150 VAC
8 mA (±1 amp) Dry Gap
16 mA (±1 amp) Wet Gap
12'' (305 mm) flying leads of
18 AWG wires
0.078'' (2 mm)
0.5 second typical
-40° to +185° F (-40° to +85° C)
-40° to +185° F (-40° to +85 °C)
2000 psig (138 bar); 1500 psig (103
bar) for transducers over 2'' (5 cm)
NEMA 4X (IP66)
ANSI/ISA-S71.03 Class SA1
ANSI/ISA-S71.03 Class VC2
Liquid Level Applications
CONTROL FUNCTIONS:
• Pump protection
• Fill line monitoring
• Interstitial space leak detection
• High or low level alarm
OF SPECIAL INTEREST TO:
• OEM Applications
• Pharmaceutical Plants
• Food Processors
5
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