OXYMAT 7 module

Заказные данные
(1)

The function of the OXYMAT 7 module is based on the paramagnetic alternating pressure method and is used to measure oxygen in gases.

Область применения

Application areas

For boiler control in incineration plants
In chemical plants
For ultra-pure gas quality monitoring
In environmental protection
For quality control
Purity control/air separator

Дизайн

Structure of high-pressure version, standard module, sample gas path with pipes

Structure of high-pressure version, field module, sample gas path with pipes

Designs – Parts wetted by sample gas, standard

Gas path		Material
With hoses	Bushing	PVDF
	Hose	FKM (e.g. Viton)
	Sample chamber	Stainless steel, mat. no. 1.4571
	O-rings/seals	FPM
	Restrictor	PTFE (e.g. Teflon)
With pipes	Bushing	Stainless steel, mat. no. 1.4571
	Pipe	Stainless steel, mat. no. 1.4404
	Sample chamber	Stainless steel, mat. no. 1.4571
	Sample gas restrictor	Stainless steel, mat. no. 1.4571
	O-rings/seals	FKM (Viton) or FFKM (Kalrez 6375)
Special applications		Materials adapted to the application

Gas path

High-pressure version with optional pressure switch for monitoring reference gas pressure


Reference gas pressure	2 000 … 4 000 hPa above sample gas pressure, but max. 5 000 hPa
Sample gas pressure
With hoses	500 ... 1 500 hPa (abs.)
With pipes	500 ... 2 500 hPa (abs.) with internal pressure sensor 500 ... 3 000 hPa (abs.) with external pressure sensor
Sample gas path	With hoses or with pipes

Gas path plan, high-pressure version with optional pressure switch for monitoring reference gas pressure

Low-pressure version with external reference gas pump


Reference gas pressure	100 hPa above the sample gas pressure (low-pressure version) for the connection of an external pump
Sample gas pressure	Atmospheric pressure ±50 hPa
Sample gas path	With hoses
Reference gas path	With hoses

Gas path plan, low-pressure with external reference gas pump, with hoses

Способ действия

Oxygen is highly paramagnetic. This outstanding property of paramagnetism is used as a physical measuring effect for oxygen analysis.

Oxygen molecules in an inhomogeneous magnetic field always move toward the higher field strength. This results in a higher oxygen concentration where the field strength is higher (higher oxygen partial pressure). If two gases with differing oxygen content are combined in a magnetic field, a (O₂ partial) pressure difference arises between them.

Since the measuring effect is always based on the difference of the oxygen content of the two gases, one refers to the sample and reference gases.

For measuring oxygen in the OXYMAT 7, the reference gas (N₂, O₂ or air) flows through two channels into the sample chamber (6). One of these partial flows enters the measuring chamber (7) in the area of the magnetic field. If the sample gas is O₂-free, the reference gas can flow out freely. If the sample gas does contain O₂, however, the oxygen molecules concentrate in the area of the magnetic field. The reference gas can then no longer flow off freely. An alternating pressure results between the two reference gas inlets. This pulsates in step with the magnetic field and depends on the oxygen concentration. This causes an alternating flow in the microflow sensor (4).

The microflow sensor consists of two nickel-plated grids heated to approximately 120ºC, which, along with two supplementary resistors, form a Wheatstone bridge. The alternating flow results in a change in the resistance of the nickel-plated grids. The resulting offset in the bridge is a measure of the concentration of oxygen in the sample gas.

Because the microflow sensor is located in the reference gas flow, the measurement is not influenced by the thermal conductivity, the specific heat or the internal friction of the sample gas. Additionally, the microflow sensor is protected through this arrangement from corrosion caused by the sample gas.

Further information

The oscillating magnetic field (8) means that the basic flow at the microflow sensor is not detected. The measurement is, thus, independent of the module's operating position or the position of the sample chamber.

The sample chamber is directly in the sample path and has a small volume, and the microflow sensor is a low-lag sensor. As a result, extremely short response times are realized.

Vibrations at the installation site can interfere with the measured signal (e.g. large fluctuations in the output signal). This behavior can be compensated for by a second (optional) microflow sensor (10), which functions as a vibration sensor. Since large differences in density between the sample and reference gases further amplify the undesired influence of vibration, reference gas is channeled to both the compensation microflow sensor (10) and the sample microflow sensor (4).

The sample gases must be fed into the analyzers free of dust. Condensation in the sample chambers must be prevented. Therefore, the use of gas modified for the measuring task is necessary in most application cases.

Flowing reference gas prevents the microflow sensor from being damaged and maintains the measurement capability of the module.

OXYMAT 7, principle of operation

Essential characteristics

Technical features

Depending on the reference gas, the physical zero point can be set between 0% and 100% oxygen.

Smallest measuring spans (up to 0.5% O₂) possible
Measuring ranges with physically suppressed zero points possible (e.g. 99.5% to 100%)
Short response time
Low long-term drift
Monitoring of reference gas pressure with reference gas connection 2 500 to 5 000 hPa (abs.) (option): reference gas pressure must be 2 000 ± 150 hPa higher than the sample gas pressure.

Features

Internal pressure sensor for correction of pressure variations in sample gas in the range from 500 to 2 500 hPa (absolute)
External pressure sensor - only with piping as the gas path - can be connected for correction of variations in the sample gas pressure up to 3 000 hPa absolute (option)
Monitoring of reference gas (option)
Analysis part with flow-type compensation circuit as an order variant for reducing the vibration impact at the installation site
For sample gas path with hoses: Connection cable to the pressure sensor with hoses
Hardware adapted to application
Customer-specific analyzer options such as:
- Drift recording
- Kalrez gaskets

Reference gases

Measuring range	Recommended reference gas	Reference gas connection pressure	Comments
0 to ... vol.% O₂	N₂	2 000 … 4 000 hPa above sample gas pressure (max. 5 000 hPa absolute)	The reference gas flow is set automatically to 5 … 10 ml/min (up to 20 ml/min with flow-type compensation branch)
... to 100 vol.% O₂ (suppressed zero point with full-scale value 100 vol.% O₂)	O₂
Around 21 vol.% O₂ (suppressed zero point with 21 vol.% O₂ within the measuring span)	Air	100 hPa with respect to sample gas pressure, which may vary by max. 50 hPa around the atmospheric pressure

Table 1: Reference gases for OXYMAT 7

Correction of zero-point error/cross-sensitivities

Accompanying gas (concentration 100 vol.%)	Zero point deviation in vol.% O₂ absolute
Organic gases
Ethane C₂H₆	-0.49
Ethene (ethylene) C₂H₄	-0.22
Ethine (acetylene) C₂H₂	-0.29
1.2 butadiene C₄H₆	-0.65
1.3 butadiene C₄H₆	-0.49
n-butane C₄H₁₀	-1.26
iso-butane C₄H₁₀	-1.30
1-butene C₄H₈	-0.96
iso-butene C₄H₈	-1.06
Dichlorodifluoromethane (R12) CCl₂F₂	-1.32
Acetic acid CH₃COOH	-0.64
n-heptane C₇H₁₆	-2.40
n-hexane C₆H₁₄	-2.02
Cyclo-hexane C₆H₁₂	-1.84
Methane CH₄	-0.18
Methanol CH₃OH	-0.31
n-octane C₈H₁₈	-2.78
n-pentane C₅H₁₂	-1.68
iso-pentane C₅H₁₂	-1.49
Propane C₃H₈	-0.87
Propylene C₃H₆	-0.64
Trichlorofluoromethane (R11) CCl₃F	-1.63
Vinyl chloride C₂H₃Cl	-0.77
Vinyl fluoride C₂H₃F	-0.55
1.1 vinylidene chloride C₂H₂Cl₂	-1.22
Inert gases
Helium He	+0.33
Neon Ne	+0.17
Argon Ar	-0.25
Krypton Kr	-0.55
Xenon Xe	-1.05
Inorganic gases
Ammonia NH₃	-0.20
Hydrogen bromide HBr	-0.76
Chlorine Cl₂	-0.94
Hydrogen chloride HCl	-0.35
Dinitrogen monoxide N₂O	-0.23
Hydrogen fluoride HF	+0.10
Hydrogen iodide HI	-1.19
Carbon dioxide CO₂	-0.30
Carbon monoxide CO	+0.07
Nitrogen oxide NO	+42.94
Nitrogen N₂	0.00
Nitrogen dioxide NO₂	+20.00
Sulfur dioxide SO₂	-0.20
Sulfur hexafluoride SF₆	-1.05
Hydrogen sulfide H₂S	-0.44
Water H₂O	-0.03
Hydrogen H₂	+0.26

Table 2: Zero point error due to diamagnetism or paramagnetism of some accompanying gases with reference to nitrogen at 60 °C und 1 000 hPa absolute (according to IEC 1207/3)

Conversion to other temperatures:

The deviations from the zero point listed in Table 2 must be multiplied by a correction factor (k):

with diamagnetic gases: k = 333 K / (ϑ [°C] + 273 K)
with paramagnetic gases: k = [333 K / (ϑ [°C] + 273 K)]²

All diamagnetic gases have a negative deviation from zero point.

Особенности

Paramagnetic alternating pressure principle

Small measuring ranges (0 to 0.5% or 99.5 to 100% O₂)

Absolute linearity

Detector element has no contact with the sample gas

Applicable in the absence of corrosive sample gases

Long service life

Physically suppressed zero point possible, e.g. in the measuring range 98% or 99.5% to 100% O₂

Схема подключения

Gas connections

Gas connections for sample gas inlet and outlet, reference gas, purging gas (optional): Fittings, 6 mm pipe diameter

Gas connections of the field module

Технические данные

The technical specifications are based on the definitions of DIN EN 61207-1.

Unless specified otherwise, the data listed below relates to the following measurement conditions:

Ambient temperature	25 °C
Atmospheric pressure	Atmospheric (approx. 1 000 hPa)
Sample gas flow	0.6 l/min (or Nl/min)
Reference gas	Nitrogen
Site of installation	Vibration- and impact-free

General information
Weight	Approx. 5.5 kg (standard version)
Measuring ranges
Number of measuring ranges	Max. 4; parameters can be assigned freely
Parameters can be assigned in the measuring ranges
Smallest possible measuring spans	0.5%, 1%, 2% or 5% O₂
Largest possible measuring span	100% O₂
Gas inlet conditions
Sample gas pressure
Standard devices with hoses	500 … 1 500 hPa (abs.)
Standard devices with hoses and ext. RG pump	Atmospheric pressure ± 50 hPa
Standard devices with pipes	500 … 3 000 hPa (abs.); briefly < 5 000 hPa (abs.)
Field module
For non-combustible gases	500 … 2 500 hPa (abs.)
For combustible gases up to gas mixtures which are occasionally explosive	800 … 1 100 hPa (abs.)
Reference gas pressure
High-pressure connection	2000 hPA above sample gas pressure (within permitted reference gas pressure range 2500 to 5000 hPa, abs.)
Low-pressure connection with external reference gas pump	100 hPa above sample gas pressure
Pressure drop between sample gas inlet and sample gas outlet	< 100 hPa at 1 l/min
Sample gas flow	18 … 60 l/h (0.3 … 1 l/min)
Sample gas temperature	0 … 60 °C
Sample gas humidity (rel. humidity)	< 90% (condensation inside the gas path is to be avoided)
Sample chamber temperature
Standard version	Approx. 72 °C
Time response
Warm-up period at room temperature	< 2 h
Response characteristics
Display delay T₉₀ with an electronic damping setting of 0 s and a sample gas flow of 1 Nl/min.	≤ 1.9 s; ≤ 2.4 s (field module including flame arrestor)
Dead time T₁₀	≤ 1.1 s; < 1.6 s (field module)
Measuring response
Output signal fluctuation with static damping constant of 0 s and dynamic noise suppression of 5% / 10 s	≤ ±0.5% of smallest measuring span (noise bandwidth corresponds to 1% = 6σ value or 0.333% = 2σ value), with vibration compensation activated: < 1.5 times the value
Detection limit	≤ 1% of smallest measuring span according to nameplate (with vibration compensation activated: < 1.5 times the value)
Measured-value drift
At the zero point	≤ ±0.5% of the smallest span/month or ≤ ±50 vpm O₂/month, whichever is greater
For span gas	≤ ±0.5% of the current measuring span/month or ≤ ±50 vpm O₂/month, whichever is greater
Repeatability
At the zero point	≤ ±0.5% of the smallest measuring span/month or ≤ ±50 vpm O₂/month, whichever is greater
For span gas	d≤ ±0.5% of the current measuring span/month or ≤ ±50 vpm O₂, whichever is greater
Linearity error with dry ambient air¹⁾	< 0.1%
Influencing variables
Ambient temperature
Deviation at zero point	≤ 0.5% of the smallest measuring span / 10 K or ≤ 50 vpm O₂/10 K, whichever is greater
Deviation of the span gas	≤ 0.5% of the current measuring span / 10 K or ≤ 50 vpm O₂/10 K, whichever is greater
Sample gas pressure
Deviation at zero point	≤ 0.2% of the smallest measuring span / 1% pressure variation or ≤ 50 vpm O₂/1% pressure variation, whichever is greater
Deviation of the span gas	≤ 0.2% of the current measuring span / 1% pressure variation or ≤ 50 vpm O₂/1% pressure variation, whichever is greater
Sample gas flow
Deviation at zero point	≤ 1% of smallest measuring span per 0.1 l/min change in flow or ≤ 50 vpm O₂ per 0.1 l/min change in flow within the permissible flow range (0.3 to 1 l/min), whichever is greater
Deviation of the span gas	≤ 1% of current measuring span per 0.1 l/min change in flow or ≤ 50 vpm O₂ per 0.1 l/min change in flow within the permissible flow range (0.3 to 1 l/min), whichever is greater
Accompanying gases	Zero point deviation (cross-sensitivity) in accordance with Table A.1 of EN 61207-3
Supply voltage	< 0.1% of the current measuring span (within the nominal range of use)
Electrical inputs and outputs
Analog and digital interfaces	See base unit
Gas connections
Connection fittings	Pipe connection with 6 mm outer diameter
Climatic conditions
Storage and transport	-30 to 70 °C
Permissible ambient temperature (during operation in base unit)²⁾	0 to 50 °C
Relative humidity (RH) during storage, transport or operation	< 90% (condensation from the installed components is to be avoided)
Materials of wetted parts
Sample chamber	Stainless steel: Plates: Mat. No. 1.4571 (X6CrNiMoTi 17-12-2) Screw-in glands: Mat. No. 1.4404 (X2CrNiMo17-12-2)
Internal gas path
With hoses	FPM (e.g. Viton), gas connections of stainless steel material no. 14404 (X2CrNiMo 17-12-2)
With pipes	Stainless steel: Pipes: Mat. No. 1.4571 (X6CrNiMoTi 17-12-2) Gas connections: Mat. No. 1.4404 (X2CrNiMo 17-12-2)
Sealing material	FPM (e.g. Viton) or FFKM (e.g. Kalrez 6375)
Special applications
Gas path
With pipes	Materials adapted to the application

¹⁾ Untreated ambient air contains less than 20.95% O₂ (literature value) since existing humidity of the oxygen content is decreased relatively.

²⁾ Restriction for installing an ULTRAMAT 7 module: 5 to 45 °C

Дальнейшая информация

Ordering example

OXYMAT 7 module built into wall box
7MB3000-3AX00-1AA0-Z+D02
7MB3020-0CE00-0AA0-Z+D02

OXYMAT 7 module and ULTRAMAT 7 module built into rack-mounted enclosure
7MB3000-0AA00-1AA0-Z+D05
7MB3020-0CE00-0AA0-Z+D05
7MB3010-0CA10-0AA0-Z+D05

OXYMAT 7 module and wall box supplied unassembled
7MB3000-3AX00-1AA0
7MB3020-0CE00-0AA0