The CONTHOS 3 PMD state-of-the-art process gas analyzer is an analytical instrument developed for use in process industry.
Some of the outstanding technical features of LFE's 3rd generation, microprocessor-controlled gas analyzer for oxygen analysis are:
The basic measuring principle of the CONTHOS 3 PMD makes use of the fact that oxygen has a paramagnetic susceptibility that is significantly greater than other gases. This property causes oxygen molecules to be attracted much more strongly into an inhomogeneous magnetic field than other gases.
The paramagnetic sensor employed in the CONTHOS 3 PMD is of the so-called "dumbbell" type utilizing the magnetomechanical measuring principle. Two miniaturized, nitrogen filled gas spheres configured in a dumbbell shape are symmetrically suspended in a strong, inhomogeneous magnetic field. Any oxygen contained in the surrounding (sample) gas is drawn into the magnetic field thereby displacing the glass spheres and forcing the dumbbell to rotate outward. The resulting torque is proportional to the oxygen concentration.
A mirror mounted on the rotational axis of the dumbbell reflects a beam of light onto a pair of photocells which detect any rotational displacement. The photocells are part of a control loop which subsequently drives current through windings arranged around the dumbbell. The current through the windings generates an electromagnetic counter moment which moves the dumbbell back to its null position. The required current level is proportional to the oxygen concentration and as such is passed on to the CONTHOS' signal processing unit.
CONTHOS 3E - PMD |
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19"-rack housing |
CONTHOS 3F - PMD |
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Field housing (protective class IP65) |
CONTHOS 3E PMD 19” rack housing | CONTHOS 3F PMD Field housing | |
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Technical specifications subject to change without notice | ||
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Enclosure & electical data | ||
Housing | 3HE/ 84TE housing for mounting in 19" cabinet | purgeable steel housing for wall mounting; with separate compartments for the electronic components and the analytical components |
Dimensions (H x W x D) | 3HU / 84TE 133 x 483 x 427 mm | 434 x 460 x 266 mm |
Weight | approx. 10 kg | approx. 25 kg |
Power requirements | 100-240 VAC (48-62Hz; nominal voltage range: 88-253 VAC; 100 VA max. during warm-up period) | |
Sample gas connectors | Standard: Swagelok® (SS 316) for tubing o.d 6 mm Option: Swagelok® (SS 316) for tubing o.d. ¼" | |
Measuring characteristics | ||
Measuring principle | Paramagnetic sensor ("dumbbell" type) | |
Measured quantity | Oxygen concentration in gas mixtures | |
Measuring ranges | Up to 3 independently configurable, switchable ranges.
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Response time T90 | < 5 sec (dependent upon gas flow and analyzer configuration; integration time configurable) | |
Influence of gas flow | between 30 – 60 l/h: < 1% of range span for a gas flow change of ±10 l/h | |
Detection limit 1 | < 1% of span | |
Reproducibility 1 | < 1% of span | |
Linearity 1 | < 1% of span | |
Response drift 1 | Zero: < 2% of span per week | |
Ambient temperature influence | Zero: < 1% of span per 10 K | |
Calibration | Manual: 2-point (offset/span) calibration (The optimal span gas concentrations should be chosen between 75 and 100 % of the corresponding range). Option: automatic or remote calibration in conjunction with the optional digital I/O board or RS-485 | |
Pressure compensation | optional: from 800 to 1200 mbar absolute; extended pressure range on request | |
Interference correction | for static and/or dynamic interference correction (dynamic correction only in conjunction with the optional analog inputs or RS-485). One of the prerequisites for dynamic interference correction is the availability of a selective signal, proportional to the particular gas component to be corrected for. The processing of analyzer ranges with a suppressed zero range is not possible. | |
Materials in contact with sample gas | ||
Paramagnetic sensor | platinum, epoxy, glass, FPM, stainless steel 1.4571 | |
Sample gas connectors | standard: stainless steel (SS 316) | |
Sample gas lines | standard: PTFE optional: stainless steel tubing (SS 321 - similar to 1.4541) and 1.4571 | |
Data display, inputs & outputs | ||
User interface | LC-display (40 characters x 16 lines) + bar graph | |
Analog signal output | 2 independently configurable, galvanically isolated analog outputs (with common ground; RLoad = 600 Ohm max) | |
Digital outputs | Instrument status (NAMUR NE 107 compliant) via floating contacts (28 V max.; 350 mA max.) | |
Analog inputs (optional) | 3 galvanically isolated, configurable analog inputs for interference correction and pressure compensation 0 – 20 mA or 4 – 20 mA (Ri = 50 Ohm) | |
Digital I/O | Digital inputs: 8 configurable, optically isolated inputs (6 - 24 VDC; 10 mA max.)
Digital outputs: 7 configurable, floating relay contacts (28 V max.; 350 mA max.)
(Note: The digital I/O board cannot be used in conjunction with the RS-485 serial interface hardware.) | |
RS-485 (optional) | with Modbus communications protocol; galvanically isolated interface | |
Service interface | non-isolated serial interface for accessing the instrument's configuration |
1 at constant temperature and pressure
CONTHOS 3 PMD Application questionnaire
Iron and Steel production – blast furnace - Process Gas Analyzer
Heat Treatment and Hardening Process - Hydrogen Process Gas Analyzer
Water Electrolysis Process - Hydrogen Process Gas Analyzer
Hydrogen Cooled Generators - TCD Process Gas Analyzer
Coal Gasification Gas Processing - Process Gas Analyzer
Air Separation Plant and Bottling - Process Gas Analyzer
Synthesis Gas - Syngas Processing - Hydrogen Process Gas Analyzer
High Temperature Applications - Hydrogen Process Gas Analyzer
Refinery Continuous Catalyst Regeneration - TCD Process Gas Analyzer
Technical specifications subject to change without notice