CONTHOS 3 - TCD
Thermal Conductivity Hydrogen Gas Analyzer

Features and typical applications

Hydrogen in (quasi) binary gas mixtures - thermal conductivity H2 gas analyzer – CONTHOS 3 - TCD

Typical Applications

Metallurgical process gases such as blast furnace, converter steel or direct reduction
Steel industry: Heat treatment & hardening
Petrochemistry: Gas processing to synthesis gas, reformer gas & coal gasification
Monitoring of gas purity, pressure swing adsorption, gas turbine cooling gas, LEL/UEL as well as inert gases
H₂ and O₂ purity in electrolysis of water

Key Features

Extremely long term stable analysis of H₂ and noble gases in binary and quasi-binary gas mixtures with lowest ranges up to 0 – 5000ppm
Extremely suppressed ranges up to 99.5 - 100%
Ultra-fast response T₉₀ ≤ 3 sec
Highly corrosion resistant TCD cell with Al₂O₃, glass and quartz for process gases with Cl₂, HCl, SO₂, H₂O
Cross compensation of up to 3 components for reduction of intereference

Description

The CONTHOS 3 state-of-the-art thermal conductivity gas analyzer is an analytical instrument developed for on-line monitoring in process industry applications.

The special outstanding technical features of LFE's microprocessor controlled gas analyzer are:

Thermal conductivity detector - thermostat controlled temperature from 50°C to max. 180°C
High corrosion resistance in the entire sample gas path
Low detection limit in the lower ppm range
Response highly independent of the gas flow
Extraordinarly high long-term stability
Intuitive user-interface based on NAMUR recommendations
Automatic self-diagnosis
Optional dynamic interference correction of up to 3 gases in conjunction with external, selective gas analyzer channels

The technical features of the unique CONTHOS 3 gas analyzer open up new areas of application for the thermal conductivity principle, as well as help to eliminate weak points in present analysis problem solving.

The selected thermostat temperature of the detector can help minimize the cross interference of possible accompanying gas components. Furthermore, accompanying gases can be measured by means of suitable external measuring methods and an interference correction of these components can be carried out.

Hydrogen in (quasi) binary gas mixtures - thermal conductivity H2 gas analyzer – CONTHOS 3 - TCD

First developed in 1979 the LFE CONTHOS gas analyzer has proven itself in many years of continuous operation in fields such as:

in corrosive process gases in the chemical and petrochemical industry
in metallurgical applications such as process gas and hardening & heat treatment
in all of the "classical" applications of the TCD principle with outstanding measurement performance

LFE's Thermal Conductivity Detector (TCD)

In conventional gas analyzers utilizing the principle of thermal conductivity a heated object is suspended in a volume containing the sample gas. Electrical energy passed through the object results in the object heating up and attaining an equilibrium temperature which is primarily dependent upon the thermal conduction properties of the surrounding gas. This temperature is normally measured directly as a change in the electrical resistance of the heated object itself.

LFE´s unique principle modifies this "classical" method by spatially and electrically decoupling the heated element from the temperature sensing element. The specially designed geometry of the TCD cell in conjunction with the decoupling effectively suppresses undesired competing thermal effects (i.e. free and forced convectional effects). The result is an instrument whose quick, stable response requires no compromise between gas flow and response time.

Features

micro-miniaturized for quick response behavior
corrosion and temperature resistant
made of aluminum oxide (Al₂O₃), glass and SiO_x-coated platinum sensor filaments

Corrosion and temperature resistant thermal conductivity detector – fast response TCD

Model variations

CONTHOS 3E - TCD

19" rack housing (protective class IP40)

CONTHOS 3F - TCD

Field housing (protective class IP65)

CONTHOS 3F - TCD Ex p

Explosion protected ATEX version for ex zone 1 & 2

CONTHOS 3F-TCD HT

High temperature version

Options

Up to 3 switchable ranges: independently configurable, suppressed & absolute (non-suppressed)
Dynamic interference correction of accompanying components in multi-component gas mixtures in conjunction with external, selective gas analyzers

Digital I/O board for remote range switching, range identification, threshold contacts, etc.
RS-485 interface with Modbus RTU protocol
TC detector with flowing reference cell (CONTHOS 3E & 3F)

Technical data

Technical Data

	CONTHOS 3E 19”-rack housing	CONTHOS 3F field housing	CONTHOS 3F - Ex p ATEX compliant Ex p system	CONTHOS 3F - HT high temperature version
Technical specifications subject to change without notice

	for mounting in 19" cabinet	purgeable steel housing for wall mounting; with separate compartments for the electronic components and the analytical components
Enclosure & electrical data
Dimensions (H x W x D)	133 x 483 x 427 mm (3U / 84HP)	434 x 460 x 270 mm	490 x 460 x 270 mm	502 x 460 x 270 mm
Protection class	IP40	IP65
Electrical hazardous area class			Protection type "px" for zones 1 & 2 according to EN 60079 Ex protective class of system: II 2 G, Ex p II T4
Weight	approx. 10 kg	approx. 25 kg	approx. 30 kg	approx. 25 kg
Power requirements	100-240 VAC (48-62Hz; nominal voltage range: 88-253 VAC; 100 VA max. during warm-up period)

	Common Technical Data CONTHOS 3E \| CONTHOS 3F \| CONTHOS 3F - Ex p \| CONTHOS 3F - HT
Technical specifications subject to change without notice
Measuring characteristics
Measuring principle	Thermal conductivity (TCD). Difference in thermal conductivity (Δλ) of various gases
Measuring ranges	Up to 3 linearized, independently configurable, switchable ranges. Suppressed output ranges within the corresponding reference range can be easily configured. Range switching is accomplished manually, automatically and/or remotely via optional digital inputs. lowest range: 0 - 0.5% H₂ in N₂ or 99.5-100% H₂ in N₂ (or equivalent Δλ) largest range: 0 - 100% H₂
Calibration	Manual: 2-point (zero / span) calibration Option: automatic or remote calibration in conjunction with the optional digital I/O-board or RS-485
Warm-up time	dependent upon TCD operating temperature as well as the ambient temperature: 70°C: approx. 20 min.; 180°C: approx. 90 min.
Response time t₉₀	≤ 3 sec (at 60 l/h gas flow and minimum signal dampening level)
Influence of gas flow	between 3 - 30 l/h: < 0.5% of range span for a gas flow change of ±10 l/h between 30 - 60 l/h: < 1% of range span for a gas flow change of ±10 l/h Higher flow rates up to e.g. 120 l/h are possible. At these higher flow rates it is recommended that the analyzer be calibrated at the operating flow rate.
Pressure influence	The TCD principle has a normally negligible pressure dependency. At very low ranges it can be seen as a proportional signal offset. Gas specific order of magnitude: < 0.02% H₂ equivalent per 100 mbar
Detection limit ¹	≤ 0.5% of span (at signal dampening level: 1 sec)
Linearity/ Accuracy ¹	≤ 0.5% of span
Reproducibility ¹	≤ 0.5% of span
Response drift ¹	Zero: ≤ 1% of span per week Span: ≤ 1% of span per week
Ambient temperature influence	Zero: ≤ 1% of span per 10 K Span: ≤ 1% of span per 10 K
Ambient temperature in operation	allowed temperature range : +5 to +45°C
Influence of inclination	no influence

	CONTHOS 3E 19”-rack housing	CONTHOS 3F field housing	CONTHOS 3F - Ex p ATEX compliant Ex p system	CONTHOS 3F - HT high temperature version
Technical specifications subject to change without notice

Materials in contact with sample gas
TC Detector	Al₂O₃-ceramic and sapphire, glass and SiO_x-coated Pt measuring filaments high corrosion and temperature resistance
Internal gas lines	standard: PTFE / PFA optional: stainless steel tubing (SS 321; similar to 1.4541) and 1.4571	standard: PTFE / PFA optional: stainless steel tubing (SS 321; similar to 1.4541)	stainless steel tubing (SS 321; similar to 1.4541)
Sample gas connectors	Standard: stainless steel (SS 316; similar to 1.4401) Standard: Swagelok^® connectors for ø6mm tubing
	Optional: Swagelok^® connectors for ø¼" tubing Optional: NPT ¼" (female)	Optional: Swagelok^® connectors for ø¼" tubing		Optional: Swagelok^® connectors for ø¼" tubing
	Optional : PFA connectors for synthetic tubing DN 4/6 (only in conjunction with PTFE tubing)

	Common Technical Data CONTHOS 3E \| CONTHOS 3F \| CONTHOS 3F - Ex p \| CONTHOS 3F - HT
Technical specifications subject to change without notice
Data display, inputs and outputs
User Interface	LC-display (40 characters x 16 lines) + bar graph Plain text description of instrument status as well as digital status output Language: switchable between English & German
Analog signal output	2 independently configurable, galvanically isolated analog outputs (with common ground; R_Load = 600 Ohm max) Available output levels: 0 - 20 mA, 4 - 20 mA, 4 - 20 mA with superimposed instrument status (NAMUR NE 43 compliant) as well as test signal levels (0, 4, 10, 12 & 20 mA)
Digital outputs 1 to 3 (instrument status)	Instrument status (NAMUR NE 107 compliant) via floating contacts (28 V max.; 350 mA max.) FAILURE (DO 1) \| MAINTENANCE REQUIRED (DO 2) \| FUNCTION CHECK (DO 3)
Analog inputs (optional)	3 galvanically isolated, configurable analog inputs for interference correction 0 - 20 mA or 4 - 20 mA (R_i = 50 Ohm)
Interference correction	3 correction channels for static and/or dynamic interference correction (dynamic correction only in conjunction with the optional analog inputs or RS-485)
Digital I/O (optional)	Digital inputs: 8 configurable, optically isolated inputs (6 - 24 VDC; 10 mA max.) remote range selection remote triggering of zero and span calibration remote triggering and cancelling of automatic calibration switching of interference correction analog inputs to a secondary input range mapping of user defined input to a digital output Digital outputs: 7 configurable, floating relay contacts (28 V max.; 350 mA max.) threshold monitoring (1 threshold per measuring range) feedback as to the current range calibration gas selection mapping of user defined input to a digital output (Note: The digital I/O board cannot be used in conjunction with the RS-485 serial interface hardware.)
Modbus interface (optional)	Modbus RTU - RS485 Modbus TCP
Service interface	non-isolated serial interface for accessing the instrument's configuration via a proprietary PC software

¹ at constant temperature and pressure

The stability data is valid for analyzer operation with pure bottled gases. Instrument accuracy is based on binary or quasi-binary gas mixtures. Deviations from the above data can occur in conjunction with process gases depending upon the gas quality and the degree of gas handling.
Unless otherwise specified the CONTHOS gas analyzer is neither ex-proof nor intrinsically safe in terms of explosion protection.
The CONTHOS may not be employed for the analysis of ignitable gas-mixtures. The customer must ensure compliance with applicable regulations when using the analyzer with inflammable or toxic gases or when installing within explosion endangered environments.
The customer must ensure that the sample gas is dry and free of particulates.