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Table of Contents
Table of Contents
1.About This Document................................................................................... 7
follow instructions carefully at this point, there is a risk of injury or even death.
CAUTION!
follow instructions carefully at this point, the product could be damaged or
important data could be lost.
Note highlights important information on using the product.
Warning alerts you to a serious hazard. If you do not read and
Caution warns you of a potential hazard. If you do not read and
7
MGP261 User GuideM212273EN-A
1.4 Trademarks
Vaisalaâ and CARBOCAPâ are registered trademarks of Vaisala Oyj.
All other product or company names that may be mentioned in this publication are trade
names, trademarks, or registered trademarks of their respective owners.
8
Chapter 2 – Product Overview
2. Product Overview
2.1 Introduction to MGP261
Vaisala CARBOCAPâ MGP261 Multigas Probe for Methane, Carbon Dioxide, and Humidity
Measurement is a compact and durable in situ probe for methane (CH4), carbon dioxide (CO2),
and moisture (H2O vapor) measurements in demanding biogas processing conditions. MGP261
probes are Ex certified for use in Ex Zone 0 (parts inserted into process) and Ex Zone 1 (parts
outside the process).
MGP261 can be installed directly into raw process gas, removing the need for sample
treatment. Application areas include anaerobic digestion of industrial and municipal waste and
sludge from waste water treatment, landfill gas monitoring, activated carbon filter monitoring
in biogas treatment process, and CHP engine feed gas monitoring.
The proprietary infrared technology of MGP261 provides superior stability and repeatability.
Thanks to condensation elimination through probe heating and corrosion-resistant steel and
plastic materials, the IP66-rated instrument is highly robust and durable.
MGP261 measurement output options include 3 analog current output channels (4 … 20 mA)
and Modbus RTU over RS-485. The probe also provides a 4 … 20 mA Ex ia input for connecting
an optional external pressure or temperature sensor.
For easy-to-use access to configuration, diagnostics, and calibration and adjustment
functionalities, MGP261 can be connected to Vaisala Insight PC software with a USB cable
accessory.
2.2
Basic Features and Options
• Available measurement parameters: methane (CH4), carbon dioxide (CO2), and moisture
(H2O vapor)
• Ex classification:Ex II 1/2 (1) G Ex eb mb [ia] IIB T3 Ga/Gb -40 °C ≤ Tamb ≤ +60 °C
• Operating pressure: -500 ... +500 mbar
• 3 analog outputs (4 … 20 mA, scalable, isolated)
• Digital output: Modbus RTU over RS-485
• Optional external temperature or pressure sensor input (4 … 20 mA, Ex ia)
• Power supply input: 18 … 30 VDC
• Direct installation into process: for pipeline ports with 1.5" female NPT thread
• Compatible with Vaisala Insight PC software
2.2.1 Hazardous Area Safety
CAUTION!
the safety information in Using MGP261 in Hazardous Locations (page 17).
Do not install or use MGP261 in a hazardous area before reviewing
9
MGP261 User GuideM212273EN-A
2.2.2 Measurement Parameters
Table 3 (page 10) shows the units and ranges of the MGP261 measurement parameters. For
further information on the measurement parameters, see Specifications (page 62).
Table 3 MGP261 Measurement Parameters
ParameterUnitMeasurement Range
Methane (CH4)Volume-%0 … 100 vol-%
Carbon Dioxide (CO2)Volume-%0 … 100 vol-%
Water Vapor (H2O)• Volume-%
• Dew point temperature
• Dew point and frost point
temperature
• 0 … 100 vol-%
• -10 … +60 °C (14 … +140 °F)
2.2.3 Wet Basis and Dry Basis Measurement Output
MGP261 methane, carbon dioxide, and water vapor measurements can be shown either as wet
basis or dry basis values. The wet basis / dry basis measurement output selection is made
when ordering the probe, and can be configured with Vaisala Insight PC software or Modbus.
Figure 1 Output Parameter Selections in Vaisala Insight PC Software
10
Chapter 2 – Product Overview
More Information
‣
Configuring Analog Outputs with Insight (page 40)
2.2.4 Installation Type
MGP261 can be installed either directly into the process (for example, through a flange or ball
valve in the actual process pipeline), or using a flow-through adapter (for example, in a
sampling line installation or when performing a field calibration).
MGP261 uses dierent internal calculation models depending on the installation type and gas
flow rate. For this reason, the type of the installation must be set correctly in MGP261 settings.
You can view and change the installation type configuration with Vaisala Insight PC software:
for instructions, see Installation Type Configuration in Insight (page 33).
CAUTION!
correctly in Insight when changing from one installation type to another, so that
the calculation model in use matches the installation environment and
measurement accuracy is not aected.
Always ensure that the installation type configuration is set
2.2.5 Process Flow Range and Installation Type
A process flow range of 2 ... 20 m/s is suitable for the in situ installation calculation model.
When operating the probe in a low flow environment (0 … 2 m/s) or using the flow-through
adapter, use the flow-through calculation model. To set the correct calculation model for the
flow range, choose the installation type in the Vaisala Insight PC software.
Process Flow Range
2 ... 20 m/sDirectly in process
0 … 2 m/s or with flow-through adapterFlow-through adapter
Installation Type Configuration in Insight (page 33)
‣
Connecting to Insight Software (page 35)
‣
Specifications (page 62)
Installation Type Selection in Insight PC Software
2.2.6 Connectivity to Vaisala Insight Software
The probe can be connected to Vaisala Insight software using a Vaisala USB cable (order code:
257295). With the Insight software, you can:
• Calibrate and adjust the measurement.
• See device information and status.
11
MGP261 User GuideM212273EN-A
• See real-time measurement.
• Configure serial communication settings, analog input and output parameters and scaling,
and environmental compensations.
More Information
‣
Connecting to Insight Software (page 35)
12
12
1
234
5
76
10911
8
Chapter 2 – Product Overview
2.3 Probe Parts
Figure 2 (page 13) shows the MGP261 main components with the connection box of the probe
closed and opened.
Figure 2 MGP261 Probe Parts (Closed and Opened View)
1
2Grounding terminal
3Lead-throughs for wiring: install cable glands as required (see Cable Gland Options and
4Connection box cover: open with connection box key to access wiring terminals
5Tightening nut: only tighten from the tightening nut when installing
61.5" male NPT thread: never install the probe to any other thread type than 1.5" female
7Probe filter
81.5" NPT thread test plug
9Wiring terminals for optional 4 … 20 mA input from external pressure or temperature
10 Barrier separating the intrinsically safe (Ex ia) optional external sensor input terminals
11Wiring terminals for 4 … 20 mA analog outputs, 18 … 30 VDC power supply input, and
12Measurement cuvette with optics and CARBOCAPâ sensor inside the probe filter
Connection box key
Lead-Throughs (page 14)) and seal unused lead-throughs
NPT thread
sensor (Ex ia)
from the analog output, power supply input, and RS-485 terminals
RS-485 communication
13
M16x1.5
M20x1.5
E
E
E - E
6 [0.24]
mm
[in]
1
2
3
MGP261 User GuideM212273EN-A
2.3.1 Cable Gland Options and Lead-Throughs
Figure 3 (page 14) shows the MGP261 cable gland options and lead-through measurements.
Cable glands are not provided by Vaisala. When selecting cable glands for your
application, note the requirements in Guidelines for Safe Use in Hazardous
Conditions (page 17).
Figure 3 Cable Gland Options and Lead-Throughs
M16x1.5 wiring lead-through (1): used when wiring the optional Ex ia external pressure or
1
temperature sensor input terminal
2 M20x1.5 wiring lead-throughs (2): used when wiring the analog output, power supply
input, and RS-485 terminals
3 The depth of the lead-throughs is 6 mm (0.24 in): the maximum thread length for the
plugs used in the lead-throughs is 8 mm (0.31 in) and the maximum cable gland length is 5
cm (1.97 in)
More Information
‣
Preparing Probe for Installation (page 26)
‣
Wiring (page 28)
14
2.4 Measurement Principle
1
2
3
Chapter 2 – Product Overview
The Vaisala CARBOCAPâ sensor used in
the probe is a silicon-based, nondispersive
infrared (NDIR) sensor for the
measurement of methane (CH4), carbon
dioxide (CO2), and humidity (H2O).
Figure 4 Probe Cuvette with Mirror and
Sensor Chips
1Mirror
2 Cuvette
3 Sensor chips under TO5 packages
The sensitivity to gases is based on absorption of infrared light at a characteristic wavelength.
During measurement, infrared light is routed through the cuvette that contains the gas to be
measured. A mirror reflects the light from the cuvette to thermopile detectors that measure
the light intensity at a wavelength determined by a Fabry–Pérot interferometer (FPI) and a
band pass filter. One set of optics measures humidity and carbon dioxide, and a second one
measures methane.
The measurement consists of two steps: first, the FPI is electrically tuned so that its pass band
coincides with the characteristic absorption wavelength of the measured gas and the signal is
recorded. Second, the pass band is shifted to a wavelength where no absorption occurs in
order to get a reference signal. The ratio of these two signals, one at the absorption
wavelength and the other at the reference wavelength, gives the fraction of light absorption
from which the gas concentration is calculated. Measuring the reference signal compensates
the possible eects of sensor aging and signal attenuation due to dirt on optical surfaces,
making the sensor very stable over time.
15
1
3
4
5
6
7
8
2
MGP261 User GuideM212273EN-A
TO5 packages with hermetic windows are used to protect the sensor chips from moisture and
contamination. A heater chip is utilized to prevent condensation in normal operation.
Figure 5 Measurement in the Measurement
Cuvette
1Mirror
2 Light absorbed by the measured gases
3 Sensor chips under TO5 packages (see
Ex II 1/2 (1) G Ex eb mb [ia] IIB T3 Ga/Gb -40 °C ≤ Tamb ≤ +60 °C
12
Ga
Gb
Chapter 2 – Product Overview
2.5 Using MGP261 in Hazardous Locations
WARNING!
specified by the product classification. The personnel installing, using, or
maintaining the probe are responsible for determining the appropriate
protection concept for the specific application the probe is used in, and that
the hazardous area classification of the probe meets the requirements of the
application.
MGP261 is certified for use in hazardous areas as defined by the following classification:
CAUTION!
have the required competencies for working in the hazardous location, as
defined by the applicable standards.
For information on the standards that apply to using MGP261 based on the classification of the
device, see MGP261 certification documentation and the declarations of conformity related to
MGP261 at www.vaisala.com/declarationofconformity.
MGP261 has been designed for use in hazardous locations as
The personnel installing, operating, and maintaining MGP261 must
2.5.1 Guidelines for Safe Use in Hazardous Conditions
Process Connection and Partition Wall
Figure 6 MGP261 Probe Ga/Gb Division
The part outside of the process (up until to the NPT 1.5" connection thread) complies with
1
the Gb Equipment Protection Level (EPL).
2 The part inside the process (starting from the NPT 1.5" thread) complies with the Ga EPL.
The partition wall is made of stainless steel, sapphire glass, and silicone adhesive. The
stress limit temperature range of the silicone adhesive is -40 … +60 °C (-40 ... +140 °F).
17
MGP261 User GuideM212273EN-A
WARNING!
flammable gas release or
While installing or uninstalling the device, there is a risk of
flame entrance.
Wiring Requirements
• The wiring of the optional intrinsically safe (Ex ia) external pressure or temperature sensor
input terminal must be kept separate from the analog input, power supply input, and
RS-485 wiring.
• See the overview in the installation instructions.
• The cable glands and wires used for wiring MGP261 must be Ex compliant.
• Unused lead-throughs must be sealed using Ex compliant plugs.
• Select a strain relief option that suits the application (either use cable glands that include
strain relief or install separate clamps: see IEC 60079-14).
• See Table 4 (page 18) for screw terminal requirements.
• Permitted supply short-circuit current (Ik): 50 A
• MGP261 analog outputs must be externally powered.
CAUTION!
input befor
Connect only de-energized wires. Never switch on the power supply
e completing the wiring and closing the connection box.
Screw Terminal Connections
Table 4 Screw Terminal Wiring Requirements
PropertySpecification
Connection torque0.5 Nm ... 0.6 Nm
Connection capacity (solid and flexible
Stripping length7 mm (0.27 in)
)
0.2 mm2 ... 2.5 mm2 (AWG 24 ... 12)
Intrinsic Safety
vervoltage category of MGP261 is I (non-mains equipment), as defined in IEC 60664-1.
The o
MGP261 is in conformance with the IEC 60079-11 dielectric strength requirement. For the
intrinsic safe IIB output parameters, see Table 5 (page 18).
Table 5 Intrinsic Safe IIB Output Parameters
ParameterValue
U
o
I
o
18
25.2 V
78 mA
Chapter 2 – Product Overview
ParameterValue
P
o
U
m
C
o
L
o
0.5 W
40 V
820 nF
20 mH
The parameters listed in Table 5 (page 18) apply when one of the two conditions below is
given:
• the total Li of the external circuit (excluding the cable) is < 1% of the Lo value; or
• the total Ci of the external circuit (excluding the cable) is < 1% of the Co value.
The parameters are reduced to 50% when both of the two conditions below are given:
• the total Li of the external circuit (excluding the cable) is ≥1% of the Lo value; and
• the total Ci of the external circuit (excluding the cable) is ≥1% of the Co value.
Note: the reduced capacitance of the external circuit (including cable) shall not be greater
than 1μF for Groups I, IIA, IIB & IIIC, and 600nF for Group IIC.
The values of Lo and Co determined by this method shall not be exceeded by the sum of all of
the Li plus cable inductances in the circuit and the sum of all of Ci plus cable capacitances,
respectively.
Connecting Probe to Insight PC Software
The Insight PC software connection cable must only be used outside the explosion hazardous
area. Remove the probe from the process for configuration, and use only the Vaisala accessory
PC connection cable to connect the probe to Insight.
Maintenance
The probe filter is the only user-replaceable part in MGP261. For other maintenance
requirements, contact Vaisala.
Live maintenance is not allowed.CAUTION!
The content in this chapter is maintained in the following separately tracked document:
Document ID: M212241ENRevision: B (21 Jan 2019)
19
MGP261 User GuideM212273EN-A
3. Installation
3.1 Overview
MGP261 can be installed either directly into the process (for example, through a flange or ball
valve in the actual process pipeline), or using a flow-through adapter (for example, in a
sampling line installation or when performing a field calibration).
For an overview of installing MGP261 directly in the process, see Installation Option: Ball Valve
Installation (page 22)
For an overview of the flow-through adapter, see Installation Option: Flow-Through Adapter
Installation (page 23)
MGP261 uses dierent internal calculation models depending on the installation type and gas
flow rate. For this reason, the type of the installation must be set correctly in MGP261 settings.
You can view and change the installation type configuration with Vaisala Insight PC software:
for instructions, see Installation Type Configuration in Insight (page 33).
CAUTION!
correctly in Insight when changing from one installation type to another, so that
the calculation model in use matches the installation environment and
measurement accuracy is not aected.
Always ensure that the installation type configuration is set
3.1.1 Process Flow Range and Installation Type
A process flow range of 2 ... 20 m/s is suitable for the in situ installation calculation model.
When operating the probe in a low flow environment (0 … 2 m/s) or using the flow-through
adapter, use the flow-through calculation model. To set the correct calculation model for the
flow range, choose the installation type in the Vaisala Insight PC software.
Process Flow Range
2 ... 20 m/sDirectly in process
0 … 2 m/s or with flow-through adapterFlow-through adapter
Installation Type Configuration in Insight (page 33)
‣
Connecting to Insight Software (page 35)
‣
Specifications (page 62)
Installation Type Selection in Insight PC Software
20
1
Chapter 3 – Installation
3.1.2 NPT 1.5" Thread Test Plug 257525SP
Figure 7 NPT 1.5" Thread Test Plug
1NPT 1.5" male thread (same as on MGP261 connector)
MGP261 comes shipped with an NPT 1.5" male thread test plug (Vaisala order code: 257525SP).
If you are uncertain about the thread type of the process connector you want to install MGP261
into, use the thread test plug to check that it fits into the process connector threads (that is,
that the process connector thread type is NPT 1.5" female).
More Information
‣
Inserting Probe into Process and Opening Connection Box (page 27)
3.1.3 Installation Preparations
Before starting the installation, check the following:
• Make sure that your installation site suits the Ex classification of MGP261:
Ex II 1/2 (1) G Ex eb mb [ia] IIB T3 Ga/Gb -40 °C ≤ Tamb ≤ +60 °C
• Review the hazardous area information in Using MGP261 in Hazardous Locations (page 17)
and make sure that the conditions for safe use are met.
• Review the wiring diagram included in this document for power supply requirements:
MGP261 requires a dedicated 24 VDC power supply. Note that in addition to the power
supply input for the probe, each analog output must be externally powered.
• Inspect the probe for any possible damage or dirt that could compromise the leak
tightness of the device (for example, bent or punctured parts of the probe body, or dirt on
the connection box threads preventing it from closing fully).
• When selecting the cable glands and plugs for your application, make sure they are Ex
compliant.
The following figure shows an example MGP261 ball valve installation. The figure
the correct wiring routes and shows the recommended installation depth and orientation.
highlights
CAUTION!
essure or temperature sensor input wiring (1), and make sure the wiring
pr
remains separated from the terminals and wiring (2) on the other side of the
metal barrier (3) on the component board.
Figure 8 MGP261 Installation Example with Wiring Routes and Recommended Orientation and
Depth
1Optional external pressure or temperature sensor input wiring (Ex ia): use the M16x1.5
2 Standard analog output, power supply input, and RS-485 communication wiring: use the
3 Metal barrier separating the intrinsically safe external sensor input terminals (optional, for
4 1.5" male NPT thread on MGP261: never install to any other thread type than 1.5" female
5 For best results, install MGP261 horizontally and position the tip of the filter within 1/3 of
ough and route the cable directly to the terminal.
lead-thr
M20x1.5 lead-throughs and route the cables to the terminals through the openings below
the component board.
environmental compensation input) from the analog output, power supply input, and
RS-485 terminals on the component board.
NPT.
the pipe's diameter from the pipe centerline. In smaller pipes, the installation depth can be
adjusted by using an adapter (for example, a ball valve).
Always use a separate cable for the optional (Ex ia) external
More Information
‣
22
R
ecommended Installation Position on Pipeline (page 24)
Figure 9 (page 23) shows MGP261 attached into the MGP261 flow-through adapter accessory
(Vaisala order code: 258877). For instructions on attaching MGP261 to the flow-through
adapter, see Attaching Flow-Through Adapter to MGP261 (page 31).
Figure 9 MGP261 in Flow-Through Adapter
258877
1Clamp with 2 screws
2 Mounting plate (attach to mounting
surface with screws or ties)
3 Probe gland tightening nut
4 Probe gland locknut: do not turn
5 Gas tube inlet port, G 1/8 (on the other
side of the adapter)
6 Gas tube outlet port, G 1/8
More Information
‣
Attaching Flow-Through Adapter to MGP261 (page 31)
‣
Flow-Through Adapter Dimensions (page 67)
23
Ø 32
[1.26]
Ø 80.5 [3.17]
1 .5” NPT
M16x1.5
M20x1.5
Ø 40 [1.57]
Ø 80.5 [3.17]
E
E
E - E
6 [0.24]
14
[0.56]
142 [5.59]
179 [7.05]
388 [15.27]
Ø 34 [1.34]
402 [15.83]
20 [0.79]
17 [0.67]
209 [8.23]
[1.85]
47
mm
[in]
≥
5 ø
≥
2 ø
1
MGP261 User GuideM212273EN-A
3.1.6 MGP261 Dimensions
Figure 10 (page 24) shows the MGP261 dimensions. The figure also shows the cabling lead-
through depth: for more information on cable gland options and lead-through dimensions, see
Cable Gland Options and Lead-Throughs (page 14).
Figure 10 MGP261 Dimensions in Millimeters and Inches
3.1.7 Recommended Installation Position on Pipeline
Figure 11 (page 24) shows the recommended installation position for MGP261. Install the
probe in a straight run of pipeline, ≥ 5 pipe diameters downstream of the closest bend or other
feature aecting gas flow, and ≥ 2 pipe diameters upstream to the next bend or similar feature.
For best results, use the orientation and installation depth shown in Figure 8 (page 22).
Figure 11 Recommended MGP261 Installation Position on Pipeline
Recommended MGP261 installation position on pipeline.
1
24
3.1.8 Gas Safety During Installation
Chapter 3 – Installation
WARNING!
flammable gas release or flame entrance.
WARNING!
(H2S)) is possible when installing or removing MGP261 from the process.
• Always follow local safety guidelines. Ensure that the work area is safe and
meets local regulations (for example, related to ventilation and personal
protective equipment).
• Use a personal gas detector to monitor the safety of the area you are
working in.
• After installation, use a gas detector to ensure that process connections are
leak-free.
CAUTION!
• Ensure that the thread type of the installation port is 1.5" female NPT. If
unsure, verify the thread type with the 1.5" NPT thread test plug.
• Apply PTFE tape to the 1.5" male NPT thread of MGP261 as instructed in
Preparing Probe for Installation (page 26), and make sure that the PTFE tape
seal has not been damaged by rotating the probe open (counter-clockwise)
in the installation port.
While installing or uninstalling the device, there is a risk of
Exposure to hazardous gases (for example, hydrogen sulfide
To avoid compromising the leak tightness of the installation:
25
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