Operating Instructions
for
Magnetostrictive Level Meter
Model: NMT
NMT
1. Contents
1. Contents ............................................................................. 2
2. Note.................................................................................... 3
3. Instrument Inspection ......................................................... 3
4. Regulation Use ................................................................... 3
5. Operation Principle ............................................................. 4
6. Mechanical connection ....................................................... 4
7. Electrical connection........................................................... 4
8. Commissioning ................................................................... 5
9. Maintenance....................................................................... 5
10. Technical Data.................................................................... 5
11. Order Codes....................................................................... 6
12. Dimensions......................................................................... 6
13. Declaration of Conformance............................................... 7
Manufactured and sold by:
Kobold Messring GmbH
Nordring 22-24
D-65719 Hofheim
Tel.: +49(0)6192-2990
Fax: +49(0)6192-23398
E-Mail: info.de@kobold.com
Internet: www.kobold.com
Seite 2 NMT 12/04
2. Note
Please read and take note of these operating instructions before unpacking and
setting the unit for operation, and follow the instructions precisely as described
herein.
The devices are only to be used, maintained and serviced by persons familiar
with these operating instructions and with the prevailing regulation applying to
procedural safety and the prevention of accidents.
3. Instrument Inspection
These devices are checked before dispatch and sent away in perfect condition.
Should the damage to a device be visible, we recommend a thorough inspection
of the delivery packing. In case of damage, please inform your parcel service/
forwarding agent immediately, since they are responsible for damages during
transit.
NMT
Scope of delivery:
• Magnetostrictive Level Meter, Model NMT
• Operating Instructions
4. Regulation Use
The level meter is to be installed only in the specified applications. Every usage
which exceeds the specifications is considered to be non-specified. Any
damages resulting therefrom are not the responsibility of the manufacturer. The
user assumes all risk for such usage. The application specifications include the
installation, start-up and service requirements specified by the manufacturer.
NMT 12/04 Seite 3
NMT
5. Operation Principle
The Kobold level meter NMT is a very accurate float-controlled sensor for the
continuous measurement of levels.
The principle of measurement is based on echo time measurement. A magnetostrictive wire is tensioned in the guide tube. Current pulses are transmitted
through the wire thus generating an annular magnetic field around the wire. The
wire is also magnetized axially by magnets fitted in the float. Due to the superimposition of both magnetic fields, a torsional impulse is generated in the vicinity of
the float magnet, which propagates with ultrasonic speed in both directions. The
distance from the float magnet to a defined zero-point is measured by an echo
time measurement. The integrated electronics transforms the signal to a standardized analog signal.
6. Mechanical Connection
Mount the level meter with guide tube on the vessel.
Use suitable flat gasket for screwing.
7. Electrical Inspection
Connect level meter according to the following wiring diagram:
GND
24 V DC
+Us
AGND
4-20mA
AOUT
Terminal assignments
GND: 0 V supply
+US: 24 VDC supply
AGND: analog output GND
AOUT: analog output 4-20 mA
-
+
-
+
Seite 4 NMT 12/04
8. Commissioning
The magnetostrictive level meter is ready for operation after mechanical and
electrical connection.
9. Maintenance
The instrument needs no maintenance when the measured medium is not
polluted.
Remove any dirt from guide tube and float with a suitable cleaning agent.
To dismantle the float, undo the retaining washer with the flat-head screw.
By installation after cleaning, secure the flat-head screw with a screw-lock fluid to
prevent loosening.
NMT
10. Technical Data
Accuracy: ± 1 mm
Measuring length: 300...2500 mm
Length of guide tube: measuring length + 114 mm
Overall length: see Dimensions
Standard density: 1.0 g/cm
Special density: 0.7 g/cm
Max. service temperature: 80 °C
Max. operating pressure: PN 10
Connection / guide tube: stainless steel 1.4571
Float: stainless steel 1.4701
Connection box: aluminium
Process connection: G 2 male or 2 NPT
Electrical connection: terminal block in connection box
Analog output: 4...20 mA 4-wire
Load: 500 ohm
Power supply: 24 V
Power consumption: < 4 W
Protection model: IP 65
± 20%
DC
3
3
NMT 12/04 Seite 5
NMT
11. Order Codes
Measuring tube st. steel
Measuring tube st. steel
Connection 4 – 20 mA
12. Dimensions
Description Model Connection
Transducer
NMT-1201
Connection G 2 AG
Density 1.0 kg/dm
Transducer
Density 0.8 kg/dm
3
NMT-1208
3
R50 = G2
N20 = 2 NPT
Seite 6 NMT 12/04
13. Declaration of Conformance
We, KOBOLD-Messring GmbH, Hofheim-Ts, Germany, declare under our sole
responsibility that the product:
magnetostrictive level meter model: NMT
to which this declaration relates is in conformity with the standards noted below:
EN 50082-2 1996-02
Electromagnetic compatibility basic specification noise immunity
DIN EN 61000-4-2 1996-03
Noise immunity to electrostatic discharge (e.s.d.)
DIN EN 61000-4-4 1996-03
Noise immunity to fast transients (BURST)
NMT
DIN EN 61010-1 1994-03
Safety requirements for electrical measuring, control and laboratory instruments
EN 60529, DIN VDE 0470-1 1992-11
Protection type through case (IP code)
Also the following EWG guideline is fulfilled:
89/336/EWG Electromagnetic compatibility
Signed: Date: 22.06.01
H. Peters M. Wenzel
NMT 12/04 Seite 7
Loading...