General information Siemens

Область применения

Fields of application

Chlorine-alkali electrolysis
Metallurgy (steel production and processing)
H₂ measurement in LNG (Liquefied Natural Gas) process
Ammonia synthesis
Fertilizer production
Petrochemicals

Special versions

Special applications

In addition to the standard combinations, special applications are also available upon request (e.g. higher sample gas pressure up to 2 000 hPa absolute).

Обзор

The CALOMAT 62 gas analyzer is primarily used for quantitative determination of one gas component (e.g. H₂, N₂, Cl₂, HCl, NH₃) in binary or quasi-binary gas mixtures.

The CALOMAT 62 is specially designed for use in corrosive gas mixtures.

Дизайн

19" rack unit

With 4HE for installation
- in hinged frame
- in cabinets with or without telescope rails
- With closed or flow-type reference chambers
Front plate for service purposes can be pivoted down (laptop connection)
IP20 degree of protection, with purging gas connection
Internal gas routes: Pipe made of stainless steel (mat. no. 1.4571)
Gas connections for sample gas inlet and outlet and for reference gas: Internal thread 1/8" – 27 NPT
Purging gas connections: Pipe diameter 6 mm or 1/4"
With closed or flow-type reference chambers

Field device

Two-door enclosure (IP65) for wall mounting with gas-tight separation of analyzer and electronic parts, purgeable
Individually purgeable enclosure halves
Gas path with screw pipe connection made of stainless steel (mat. no. 1.4571), or Hastelloy C22
Purging gas connections: Pipe diameter 10 mm or 3/8"
Gas connections for sample gas inlet and outlet and for reference gas: Internal thread 1/8" – 27 NPT
With closed or flow-type reference chambers

Display and control panel

Large LCD field for simultaneous display of:
- Measured value (digital and analog displays)
- Status bar
- Measuring ranges
Contrast of the LCD field adjustable via the menu
Permanent LED backlighting
Washable membrane keyboard with five softkeys
Menu-driven operator control for parameterization, test functions, adjustment
Operator support in plain text
Graphical display of the concentration progression; time intervals parameterizable
Bilingual operating software German/English, English/Spanish, French/English, Spanish/English, Italian/English

Input and outputs

One analog output per medium (from 0, 2, 4 to 20 mA; NAMUR parameterizable)
Two analog inputs configurable (e.g. correction of cross-interference or external pressure sensor)
Six binary inputs freely configurable (e.g. measurement range changeover, processing of external signals from the sample preparation)
Six relay outputs, freely configurable (e.g. failure, maintenance request, threshold alarm, external magnetic valves)
Each can be expanded by eight additional binary inputs and relay outputs (e.g. for autocalibration with max. four test gases)

Communication

RS 485 present in basic unit (connection from the rear; for the rack unit also behind the front plate).

Options

RS 485/RS 232 converter
RS 485/Ethernet converter
RS 485/USB converter
Connection to networks via PROFIBUS DP/PA interface
SIPROM GA software as the service and maintenance tool

CALOMAT 62, membrane keyboard and graphic display

Designs – parts wetted by sample gas

Gas connection	19" rack unit	Field device
Input block with gas connection	Stainless steel, mat. no. 1.4571	Stainless steel, mat. no. 1.4571
Seal	FPM (e.g. Viton) or FFPM	FPM (e.g. Viton) or FFPM
Sensor	Glass	Glass
Input block with gas connection		Hastelloy C22
Seal		FFPM (e.g. Kalrez)
Sensor		Glass

CALOMAT 62, 19" rack unit, gas path

CALOMAT 62, field device, gas path

Функции

Principle of operation

The measuring principle is based on the different thermal conductivity of gases.

The temperature of a heated resistor surrounded by gas is determined by the thermal conductivity of the gas. Four such resistors are connected as a bridge.

Sample gas flows around two of them, reference gas surrounds the other two. A constant DC voltage heats the resistors above the temperature of the measurement block.

The different thermal conductivities of the sample and reference gases result in different temperatures of the resistors. A change in the composition of the sample gas thus also causes a change in the resistance values.

The electrical equilibrium of the measuring bridge is disrupted, and a voltage is generated in the bridge diagonal. This is a measure of the concentration of the measured component.

Note

The sample gases must be fed into the analyzers free of oil, grease, and dust. The formation of condensation in the sample chambers (dew point of sample gas < ambient temperature) must be avoided. Therefore, gas prepared for the respective task must be provided in most applications.

CALOMAT 62, principle of operation, example of a non-flow-type reference chamber

Important features

Four freely-programmable measuring ranges, also with suppressed zero, all ranges linear
Smallest spans down to 1 % H₂ (with suppressed zero: 99 to 100 % H₂) possible
Measuring range identification
Electrically isolated measured-value output 0/2/4 to 20 mA (also inverted)
Automatic or manual measuring range switchover selectable; remote switching is also possible
Measured value can be saved during adjustment
Time constants are selectable within wide ranges (static/dynamic noise suppression); i.e. the response time of the analyzer can be adapted to the respective task
Short response time
Low long-term drift
Measuring point switchover for up to 6 measuring points (parameterizable)
Measuring point identification
External pressure sensor can be connected – for correction of variations in sample gas pressure
Possibility for correcting the influence of residual gases (correction of cross-interference)
Automatic measuring range calibration can be programmed
Operation based on the NAMUR recommendation
Two operator input levels with their own authorization codes to prevent unintentional and unauthorized interventions
Simple handling using a numerical membrane keyboard and operator prompting
Customer-specific device versions, such as:
- Customer acceptance
- TAG labels
- Drift recording
- Clean for O₂ service

Spans

The smallest and largest possible spans depend on both the measured component (gas type) and the respective application (see ordering data).

Cross-interferences

Information on the sample gas composition is required in order to determine the cross-interference of residual gases with several interfering components.

The zero offsets in % H₂ which result from 1 % residual gas (interfering gas) are listed in the following table; the specified values are approximate values.

It should be noted that the influence of interfering gas is not linear to its concentration. Information on the sample gas composition is required in order to determine the cross-interference of residual gases with several interfering components.

Ar	Approx. - 0.15 %
O₂	Approx. + 0.02 %
CO₂	Approx. - 0.13 %
CH₄	Approx. + 0.17 %
SO₂	Approx. - 0.31 %
Air (dry)	Approx. + 0.25 %

Effect of 1 % gas component with nitrogen as the residual gas, expressed in % H₂

Moreover, it must be noted that - in addition to a zero offset - the gradient of the characteristic can also be affected by the residual gas. However, this effect is negligible in the case of variations in the interfering gas concentration below 10 %.

Taking these facts into consideration and due to the fact that the cross-interference analyzers cause further measuring inaccuracies, a larger error in measurement occurs than with binary gas mixtures despite correction of cross-interference.

Specification for the interface cable

Surge impedance	100 ... 300 Ω, with a measuring frequency of > 100 kHz
Cable capacitance	Typ. < 60 pF/m
Core cross-section	> 0.22 mm², corresponds to AWG 23
Cable type	Twisted pair, 1 x 2 conductors of cable section
Signal attenuation	Max. 9 dB over the whole length
Shielding	Copper braided shield or braided shield and foil shield
Connection	Pin 3 and pin 8

Bus terminating resistors

Pins 3-7 and 8-9 of the first and last connectors of a bus cable must be bridged (see figure).