Honeywell MPD Series User manual

Operating Manual
Multi-Purpose Detector (MPD)

MPD Operating Manual 3
Safety......................................................................................................5
1. Introduction .......................................................................................8
1.1.1 Naming Conventions .......................................................8
1.2 Principle of Operation..............................................................9
1.2.1 Catalytic Bead Sensor MPD-**-CB1................................9
1.3 Accessories..............................................................................9
1.3.1 Collecting Cone .............................................................10
1.3.2 Weatherproof Cap..........................................................10
1.3.3 Sample / Calibration Gas Flow Adaptor ........................11
1.3.4 Gassing Point Assembly................................................11
1.3.5 Duct Mount Kit...............................................................12
1.3.6 Filters .............................................................................12
2. Installation .......................................................................................13
2.1 Unpacking...............................................................................13
2.2 Sensor Orientation.................................................................13
2.3 MPD Remote Mount ...............................................................13
2.4 Wiring......................................................................................14
2.4 Cable Connections.................................................................14
2.5 Fitting Sensors.......................................................................15
3. Fitting Accessories .........................................................................16
3.1 Collecting Cone......................................................................16
3.2 Weatherproof Cap..................................................................16
3.3 Sample/Calibration Gas Flow Adaptor.................................16
3.4 Filters ......................................................................................16
3.5 Duct Mount Kit........................................................................16
4. Maintenance.....................................................................................17
4.1 General....................................................................................17
4.2 Cleaning..................................................................................17
5. Faults................................................................................................18
6. Functional Gas Test (Bump Test).................................................. 19
6.1 Sensor without Accessories ................................................19
6.2 Sensor with Collecting Cone or Weatherproof Cap............19
6.3 Sensor with Sample/Calibration Gas Flow Adaptor ...........19
7. Calibration........................................................................................20
7.1 Zero and Span Calibration for MPD Sensors with XNX
Universal Transmitter ..............................................................20
7.2 Cross Calibration procedure for MPD-CB1 .........................22
7.3 MPD-CB1 Flammable Sensor Operational Life ...................24
7.4 Meter Multiplication Factors for MPD-IF1 ............................24
8. Replacement Parts..........................................................................25
Table of Contents

MPD Operating Manual
4
8.1 MPD Catalytic Bead and IR Replacement Sensor Cartridges
.......................................................................................................25
8.2 Terminal Housings.................................................................25
8.3 Maintenance Spares ..............................................................25
8.4 MPD Calibration Gases..........................................................26
9. Specifications..................................................................................26
9.1. General Specifications .........................................................26
9.2 Performance Data ..................................................................26
9.3 MPD-CB1.................................................................................28
9.2.1 MPD-CB1 Cross Sensitivity...........................................28
9.4 MPD-IV1...................................................................................29
9.5 MPD-IF1...................................................................................30
9.6 MPD-IC1 ..................................................................................31
9.7 MPD Certifications by Part Number Series..........................32
9.7.1 MPD Certification Labels ...............................................33
10. Warranty.........................................................................................34
11. EC Declaration of Conformity ......................................................36

MPD Operating Manual 5
Safety
»Ensure that this Operating Manual is read and understood BEFORE installing, operating,
or maintaining the equipment.
»Pay particular attention to Warnings and Cautions.
»All document Warnings and Cautions are listed here and repeated where appropriate in
the relevant chapter(s) of this Operating Manual.
WARNINGS
»Agency approvals are associated with specific Sensor/Housing combinations
rohibiting field upgrade of sensor types. The MPD part number, serial number, sensor
type and target gas should be provided when ordering replacement sensors (See
Section 8.1 MPD Catalytic Bead and IR Replacement Sensor Cartridges).
»High off-scale readings may indicate an explosive concentration of gas.
»To maintain safety standards, regular maintenance, calibration and operation of this
equipment by qualified personnel is essential. Read and understand this manual
completely before operating or servicing. If any further details are required which
do not appear in this manual contact Honeywell Analytics or their agent.
»The Code of Practice regarding ‘Selection, Installation and Maintenance of Electrical
Apparatus for use in Potentially Explosive Atmospheres’ must be complied with at all
times. Refer to the appropriate local or national regulations relative to the installation
site. Elsewhere the appropriate local and/or national regulations should be used.
»As some test gases may be hazardous, the Flow Adaptor outlet should exhaust into
a safe area.
»Operators must be fully aware of the action to be taken if the gas concentration
exceeds an alarm level.
»Before installing the sensors, isolate the power supply by disconnecting or removing
the associated control module from the installation.
»Appropriate care should be taken when handling cylinders of compressed flammable
and toxic gases during calibration and bump testing.

MPD Operating Manual
6
CAUTIONS
»To maintain safety standards, regular maintenance, calibration and operation of the
equipment by qualified personnel is essential.
»Do not modify or alter the sensor construction as essential safety requirements
may be invalidated.
»When replacing sensors, dispose of used sensors in accordance with local
disposal regulations. For more information on sensor disposal, contact your HA
Representative.
»The catalytic detector element is resistant to catalyst poisons, however, abnormally
high concentrations of halogenated hydrocarbons, vapors of heavy metals or
compounds, some silicone compounds and sulfur compounds may cause loss of
sensitivity.
»The MPD must never be used in conditions where there is insufficient oxygen to
totally oxidize the combustible gas. For most combustible gases, an oxygen level
of at least 15% is sufficient.
»The sintered disc on the sensor assembly must be kept free from contaminants;
i.e. oil and dirt.
»The sensitivity of catalytic sensors is impaired by silicone compounds. Do not expose
the sensors to silicones or silicone-based products.
»The relevant site procedures must be obeyed at all times when opening the Terminal
Housing or removing the sensor in a hazardous areas.
»The sensitivity of Catalytic Sensors is impaired by silicone compounds. Do not expose
to silicones or silicone based products.
»Dismantling of a sensor or a sensor installation by other than authorized engineers
invalidates certification.
»Upward pressure on the gassing nozzle of the Weatherproof Cap forces the nozzle
against the sinter. Rotation of the nozzle may damage the sinter if a filter is not fitted.
»Direct gassing of the sensor via the nozzle on the Collecting Cone in wind speeds of
greater than 5 meters per second may cause errors.
»The calibration procedure should only be performed by qualified personnel.
»Before initial calibration allow the detector to stabilize for 30 minutes after applying
power. When in zero and span calibration mode the current output from the detector
is inhibited (e.g. default 2mA) to avoid false alarms.
»Extended or frequent exposure to elevated concentrations of combustible gases
may affect sensor sensitivity. Verify sensor performance by frequent calibration.
»Where the user calibrates any sensor using a different gas, responsibility for dentifying
and recording calibration rests with the user. Refer to the local regulations where
appropriate.
»These (meter multiplication) factors only apply to gas concentrations expressed in
% Volume terms.

MPD Operating Manual 7
»When using a linear cross reference factor the temperature compensation is based
upon propane, and there may be errors at temperatures away from the calibration
temperature.
»To maintain safety standards, regular maintenance, calibration and operation of the
equipment by qualified personnel is essential.
»Do not modify or alter the sensor construction as essential safety requirements
may be invalidated.
»When replacing sensors, dispose of used sensors in accordance with local
disposal regulations. For more information on sensor disposal, contact your HA
Representative.
ATEX Temperature Code Ratings
»Component gets no hotter than an operating temperature code of T4 when installed
according to the electrical specifications of Label ( Sch Drawing 1226E0309)
»Maximum surface temperatures is less than 85°C when measured under normal
operating conditions for the Dust evaluation.
Important Notices
Every effort has been made to ensure the accuracy of the contents of our documents,
however, Honeywell Analytics can assume no responsibility for any errors or omissions in
our documents, or their consequences.
Honeywell Analytics can take no responsibility for installation and/or use of its equipment if
this is not done in accordance with the appropriate issue and/or amendment of the manual.
The user of this manual should ensure that it is appropriate in all details to the exact equipment
to be installed and/or operated. If in doubt, the user should contact Honeywell Analytics for
advice.
If further details are required which do not appear in this manual, contact Honeywell Analytics
or one of their agents.

MPD Operating Manual
8
1. Introduction
The MPD (Figure 1) is a serviceable explosion proof housing, offered with either
catalytic bead or infrared sensors for the measurement of ammable and toxic
gases. The assembly is constructed of 316 stainless steel and is supplied in either
¾ inch NPT or M25 thread versions with corresponding approvals (See Section
10 - Specications). The sinter assembly can easily be removed for same sensor
replacement.
WARNING:
Agency approvals are associated with specific Sensor/Housing combinations
prohibiting field upgrade of sensor types. The MPD part number, serial number,
sensor type and target gas should be provided when ordering replacement sensors
(See Section 8.1 MPD Catalytic Bead and IR Replacement Sensor Cartridges).
The MPD can be mounted directly to a transmitter such as the XNX Universal
Transmitter or other suitable device in a hazardous area, or remotely mounted to a
transmitter located in a non-hazardous area. For remote mounting, the detector is
tted to an optional junction box. The ¾ NPT type is supplied with factory sealed
leads eliminating the need for a pour gland between the detector and the junction
box.
Optional accessories such as collecting cone, weatherproof cap or alternative
sampling systems can be installed to the MPD via the M40 external thread provided
on the sensor retainer. A M40 (female) to M36 (male) adaptor can be ordered,
offering additional accessory selections.
The presence of target gas is indicated via a millivolt electrical interface for all
sensor types via three wires. Two additional wires provide a digital interface for
the infrared version. When appropriately interfaced with a controller, the controller
can provide outputs such as display, 20mA, relay, etc.
The MPD detector must be installed in accordance with local and national
requirements for the installed area and application. Reference drawing number
1226E0351 for specic installation requirements.
Honeywell recommends periodic bump testing of the sensor to ensure proper
operation and compliance with the functional safety rating of the installation.
1.1.1 Naming Conventions
MPD sensor models are in the format MPD-XX-YYY. XX designates agency approval
(AM = ATEX/IEC Ex with male M25 thread, UT = UL/CSA or UL with male 3/4“
NPT thread, BT = UL/INMETRO with male 3/4“ NPT thread), YYY designates the
sensor Type (CB1 = Catalytic bead % LEL, IF1 = Infrared % LEL, IV1 = Infrared %
LEL CH4, IC1 = Infrared CO2).

MPD Operating Manual 9
3/4” NPT or M25 Threads
Sensor Cell
Sensor Retainer
and Locking Screw
1.875 [47.63]
2.080 3.016
[76.62]
2.016
[51.21]
(All dimensions reference)
20AWG Stranded Wire
7.5 [190.5] Nominal Length
[52.83]
Figure 1. Multi-Purpose Detector (MPD)
1.2 Principle of Operation
1.2.1 Catalytic Bead Sensor MPD-**-CB1
The CB1 sensor, catalytic bead type contains two elements which are heated by a
dened constant electrical current from the transmitter. One element is sensitive to
the presence of combustible gas, the second element compensates for changes in
temperature. When a combustible gas is present, the sensing element temperature
increases due to catalytic oxidation of the gas. The resistance of the element is
proportional to temperature and is proportional to a change to gas concentration.
The catalytic bead sensor provides the broadest range of combustible detection,
widest temperature range and performance approvals.
1.2.2 Infrared Sensor MPD-**-IF1, IV1, IC1
The IF1, IV1and IC1sensors use Non-Dispersive InfraRed (NDIR) Adsorption
techniques to detect a gas or family of gases. The sensor cells contain a long life
tungsten lament infrared light source, an optical cavity into which gas diffuses,
a dual temperature compensated pyroelectric infrared detector, and integral
semiconductor temperature sensor and electronics to process the signals from
the pyroelectric detector.
The IV1 sensor can measure methane concentration in the range of 0-5%Vol or
0-100%LEL. The IF1 sensor can measure propane concentration in the range of
0-100%LEL. The IC1 is used for carbon dioxide monitoring in the rage of 0-5% Vol.
1.3 Accessories
The following accessories are available for use with the sensors:
a. Collecting Cone (Figure 3).
b. Weatherproof Cap (Figure 4).
c. Sample/Calibration Gas Flow Adaptor (Figure 5).
d. Remote Gassing Port (Figure 6).
e. Duct Mount Kit (Figure 7).
f. Filters

MPD Operating Manual
10
1.3.1 Collecting Cone
(02000-A-1642)
The detection of a lighter than air gas is enhanced by the use of a Collecting Cone.
The cone ts onto the Sensor accessory thread in place of the Filter Housing and
retains the lter. The appropriate lter must be tted.
A nozzle on the cone permits gassing of the Sensor with the cone in position. Test
gas is applied either direct to the nozzle or via a permanently connected pipe-line
when the Sensor is in an inaccessible location.
Figure 2. Collecting Cone
1.3.2 Weatherproof Cap/Housing
(Cap: 02000-A-1640, Housing: SPXCDWP)
The Weather Protection Housing, tted to a sensor installed in an exposed location,
affords protection from driving rain from vertical to 30° below horizontal. When
mounted close to the ground, protection is afforded from heavy rain rebounding
off the ground. It also reduces contamination from industrial waste and enables
the application of test gas in high wind speeds without signicant error.
Incorporated in the housing is a nozzle to facilitate gassing of the sensor with the
Weather Protection Housing in position, either by direct application to the nozzle or
via a permanently connected pipeline. On the Weatherproof Cap (02000-A-1640),
the nozzle is free to rotate within the housing to allow removal from the sensor
without disconnecting a permanently connected pipeline, when changing the
Hydrophobic Barrier and cleaning the sensor.
MPD
Sensor Accessory Thread
Weatherproof Cap
Figure 3. MPD, Adaptor and Weatherproof Cap
Figure 4. Weatherproof Housing

MPD Operating Manual 11
1.3.3 Sample / Calibration Gas Flow Adaptor
(1226A0411)
A Flow Adaptor provides a facility to allow sampling of a closed system by means
of two pipelines. The Flow Adaptor is tted to the sensor accessory thread by a
locking ring that enables the Flow Adaptor to be removed without disconnecting
the pipeline. The Filter is retained by the Flow Adaptor and interfaces with a gasket
bonded to the Flow Adaptor. The Flow Adaptor ports are designed to be tted
with 1/4 in (6mm) soft tubing.
The Flow Adaptor is also used to apply calibration gas to the sensor. See Section
7 - Calibration for further details on calibrating the detector.
Figure 5. Flow Adaptor / MPD with Flow Adaptor
1.3.4 Gassing Point Assembly
(1226A0354)
The Gassing Point Assembly assembly can be xed in a convenient position and
permanently connected by suitable tubing to an inaccessible sensor, thus simplifying
the application of test gas when checking sensor calibration. A DIN Rail Mounting
Assembly (00785-A-0069) is available to enable ve gassing point assemblies to
be mounted side by side.
Tube Cap
Mounting Bracket
1/4 in (6mm) I.D.
Teflon®Tubing
Device Adapter
Figure 6. Remote Gassing Port

MPD Operating Manual
12
1.3.5 Duct Mount Kit
The duct mounting kit (S3KDMK), combined with the MPD Interface Adaptor
(1226A0382), can accommodate the MPD to detect ammable gases in a duct
application. The duct mount kit includes the adaptor, gasket and required fasteners.
The MPD Interface Adaptor includes only the adaptor and requires the S3KDMKduct
mount kit.
1226A0382 MPD Adapter Ring
S3KDMK EC/MPD Duct Adapter Kit
Figure 7. Duct Mount Kit
1.3.6 Filters
In a clean atmosphere, and where no accessories are to be tted, a lter is not
needed. It is however mandatory that a lter should be tted to provide protection
appropriate to the environment and to complete the seal when a Weatherproof
Cap or Collecting Cone is tted.

MPD Operating Manual 13
2. Installation
WARNING
The Code of Practice regarding ‘Selection, Installation and Maintenance of
Electrical Apparatus for use in Potentially Explosive Atmospheres’ must be
complied with at all times. Refer to the appropriate local and/or national regulations
relative to the installation site. Elsewhere the appropriate local and/or national
regulations should be used.
CAUTIONS
The catalytic detector element is resistant to catalyst poisons, however, abnormally
high concentrations of halogenated hydrocarbons, vapors of heavy metals or
compounds, some silicone compounds and sulfur compounds may cause loss of
sensitivity.
The MPD must never be used in conditions where there is insufficient oxygen to
totally oxidize the combustible gas. For most combustible gases, an oxygen level
of at least 15% is sufficient.
The sintered disc on the sensor assembly must be kept free from contaminants;
i.e. oil and dirt.
2.1 Unpacking
On receipt the equipment must be carefully unpacked, observing any instructions
printed on the packaging, and the contents checked for deciencies and transit
damage.
2.2 Sensor Orientation
The sensor must be installed with the Sensor facing downwards. For MPD-BT-
IC1 and MPD-UT-IC1 performance approval, the supplied SPXCDWP weather
protector must be installed in order to meet published performance standards. In
environments requiring IP66 protection, the SPXCDWP must be tted.
2.3 MPD Remote Mount
The MPD can be remote mounted using an approved junction box and
interconnecting conduit or cabling. The Junction Box and installation must be in
compliance with all local requirements for the area in which the unit is installed.
• The MPB UT versions must be installed a minimum of 5 1/4 turns into the
Junction box or Transmitter to maintain approval rating.
• The MPD Leads are factory sealed, which relieves the requirement for a
pour tting between the junction box and sensor.
UL/CSA Aluminum Junction Box
2441-0022
ATEX/IEC Junction Box
00780-A-0100
Figure 8. Terminal Housings

MPD Operating Manual
14
2.4 Wiring
NOTe:
To maintain EMC integrity, wiring must be shielded by either an integral
shield or run through conduit or pipe. Shield should provide 90%
coverage.
The MPD Sensor must be operated from a transmitter supplied by a Class 2 Power
Supply.
For remote sensor installations, ensure the resistance of the wire is considered
in the interface of the sensor to maintain proper operation. For XNX the following
values should not be exceeded:
AWG Metric Wire Gauge
(mm2)
MPD CB1 Sensors
(distance in meters)
MPD IC1, IV1 & IF1 Sensors
(distance in meters)
24 0.25 12 (47 ft.) 30 (97 ft.)
22 20 (65 ft.) 50 (162 ft.)
20 0.5 30 (97 ft.) 80 (260 ft.)
18 50 (162 ft.) 120 (390 ft.)*
16 1.0 80 (260 ft.)* 200 (650 ft.)*
* Frequency of zero calibration may increase due to the changes in wire resistance at different
temperatures.
2.4 Cable Connections
The sensor is connected by three wires:
Connections Color Code
Sensitive (S) Brown
Non-sensitive (NS) Blue
Common (01) White
A 3-way terminal block is provided in the terminal enclosure to enable connection
to be made to the control unit. Earthing facilities are available if required.
NOTe
The black and red wires from the MPD are not used with the XNX mV Personality
Board. Insure they are properly isolated from live connections. DO NOT CUT.

MPD Operating Manual 15
2.5 Fitting Sensors
WARNING
Before installing the sensors, isolate the power supply by disconnecting or
removing the associated control module from the installation.
CAUTION
• The sensitivity of catalytic sensors is impaired by silicone compounds. Do not
expose the sensors to silicones or silicone-based products.
• The sintered disc on the sensor assembly must be kept free from containments;
i.e. oil and dirt.
• The relevant site procedures must be obeyed at all times when opening the
Terminal Housing or removing the sensor in a hazardous areas.
If replacing a sensor refer to CAUTION 1 in Section 4 - Maintenance.
To t the MPD proceed as follows:
1. Remove the protection disc and t the accessories as required. (Refer to
Section 3 - Fitting Accessories).
2. Isolate the power supply and wait for ve minutes.
3. Remove the Terminal Housing lid.
4. Pass the cable into the Terminal Housing and t the sensor to housing.
To comply with the certication requirements, a minimum of ve threads
must be engaged.
5. Connect the sensor cable to the terminal block. (See the label adjacent
to the connector).
6. After mounting the Terminal Housing in the required location, connect the
associated Control Module wiring to the terminal block (see the label).
7. Replace and secure Terminal Housing lid.
8. If not already replaced by accessories, unscrew the Filter Housing, remove
the protection disc and replace Filter Housing and gasket.
NOTe
The Hydrophobic Barrier is retained in position by the Filter Housing, or
one of the accessories.
9. Connect power supply to the Sensor by reconnecting or replacing the
associated Control Module.
10.Calibrate the system as detailed in the equipment manual.
NOTe:
Calibration of the MPD is mandatory before the detector can be used for
gas monitoring. Refer to Section 7 - Calibration for the proper procedure.

MPD Operating Manual
16
3. Fitting Accessories
3.1 Collecting Cone
(02000-A-1462)
To t the Collecting Cone to a sensor, carry out the following:
1. Remove the Filter Housing and gasket from the sensor.
2. Fit the Stainless Steel Filter.
3. Screw the Collecting Cone onto the sensor accessory thread and
tighten rmly by hand.
See Appendix A in the XNX Technical Manual for more Local HART Handheld.
information.
3.2 Weatherproof Housing
(SPXCDWP)
For FM 6340 performance approvals on MPD-BT-IC1 and MPD-UT-IC1,
SPXCDWP must be installed for IP66 compliance.
Note: Environmental conditions that compromise the IP66 protection
provided by the weather proof cover will extend published response
times. Safety protocols or maintenance procedures that consider these
environmental conditions are recommended specic to the installation.
3.3 Weatherproof Cap
(02000A1640)
To t a Weatherproof Cap to a sensor carry out the following:
1. Remove the Filter Housing and gasket from the sensor.
2. Fit the Stainless Steel Filter.
3. Screw the Weatherproof Cap on to sensor accessory thread and
tighten rmly by hand.
3.4 Sample/Calibration Gas Flow Adaptor
(1226A0411)
To t a Flow Adaptor to the sensor, carry out the following:
1. Remove the Filter Housing and gasket from the sensor.
2. Ensure that the Flow Adaptor is tted with its gasket.
3. Apply a thin coating of anti-seize compound, such as light petroleum
grease, to the sensor accessory thread.
4. If required t the Stainless Steel Filter, screw the Flow Adaptor on
to the sensor and tighten with a 47mm A/F spanner.
5. Set the sample ow rate to 0.5 ± 0.2 liters per minute, unless
otherwise directed in System installation instructions.
See Appendix B in the XNX Technical Manual for more Modbus. information.
3.5 Duct Mount Kit
The Duct Mounting Kit (S3KDMK), when combined with the MPD
Interface Adaptor (1226A0382), the Duct Mounting Kit can
accommodate the MPD to detect ammable gases in a duct application.
The kit includes the adaptor, gasket and required fasteners. The MPD
Interface Adaptor includes only the adaptor and requires the S3KDMK
Duct Mounting Kit.

MPD Operating Manual 17
4. Maintenance
4.1 General
Maintenance consists of cleaning the sensor and accessories, replacing gasket
and the Hydrophobic Barrier and gassing the sensor when testing the system.
CAUTIONS
• The sensitivity of Catalytic Sensors is impaired by silicone compounds. Do
not expose to silicones or silicone based products.
• Dismantling of a sensor or a sensor installation by other than authorized
engineers invalidates certification.
In the event of exposure to contaminant or prolonged exposure to high concentration
of gas, the sensor should be operated for 24 hours in a clean environment and
then recalibrated.
NOTe
If the sensor is found to be faulty, or cannot be calibrated, the sensor
cartridge is replaceable.
Dispose of in accordance with local disposal regulations. For more
information on sensor disposal, contact your HA Representative.
4.2 Cleaning
Sensor and accessories may be cleaned using an industrial grade of methanol,
providing the appropriate safety precautions are taken when handling this solvent.
4.3 Sensor Cell Replacement
Using Figure 8 as a guide, follow the procedure below:
1. Check that the label on the new sensor cell is the correct gas type.
2. Remove power from the transmitter.
3. Unscrew the weatherproof cover (if equipped), loosen the retainer locking
screw and unscrew the sensor retainer.
4. Remove the old sensor cell by pulling without twisting.
5. Replacement cartridges are designed to seal against an O-ring in the sensor
retainer. Verify O-ring described is in place prior to reassembly.
6. Slide the replacement cell into the MPD body taking care to align the tab
with the alignment slot, then press the cell rmly to seat it into the body.
7. Ret the sensor retainer, tighten until hex is ush with the body of the sensor.
8. Tighten the locking screw and ret the weatherproof cover (if equipped).
9. Recalibrate the detector following the procedures in Section 7.

MPD Operating Manual
18
Cell Alignment Slot
Sensor Cell
IR or Cat Bead
Sensor Retainer
and Locking Screw
Internal O-ring
(critical to performance times)
Figure 9. Replacing Plug In Sensor
5. Faults
The following table provides a list of possible faults related to the sensor together
with possible causes and remedies.
Fault Cause/Remedy
Sensor reads non-zero all the time Gas could be present, ensure there is no
combustible gas in the atmosphere.
Sensor reads non zero when no gas is present Adjust the zero of the control system.
Sensor reads low when gas is applied Adjust the span of the control system.
Sensor reads high when gas is applied Adjust the span of the control system.
Sensor reads zero when gas is applied
• check the wiring.
• check that the dust protection cap has been
removed.
• check that the sinter is not obstructed.
• replace the sensor if poisoning is suspected.
In the event of exposure to contaminant, e.g. silicones or silicone based products,
or prolonged exposure to high concentration of gas, the sensor should be operated
for 24 hours in a clean environment and then recalibrated.
If the sensor is found to be faulty, or cannot be calibrated, the complete sensor
must be discarded and replaced.

MPD Operating Manual 19
6. Functional Gas Test (Bump Test)
6.1 Sensor without Accessories
Where there are no accessories tted, it is recommended that a Flow Adaptor is
used when gassing the sensor. Where this is not possible, a suitable plastic bag
may be used.
6.2 Sensor with Collecting Cone or Weatherproof Cap
1. Using the rubber tubing, connect the test gas to the gassing nozzle or to
the permanently connected tubing if tted.
CAUTION
• Upward pressure on the gassing nozzle of the Weatherproof Cap forces the
nozzle against the sinter. Rotation of the nozzle may damage the sinter if a
filter is not fitted.
• Direct gassing of the sensor via the nozzle on the Collecting Cone in wind
speeds of greater than 5 meters per second may cause errors.
2. Set the ow rate to 1.5 ± 0.1 liters per minute and test the system in
accordance with the instructions in the appropriate system equipment
manual.
3. On completion, shut off the test gas and disconnect the rubber tubing.
6.3 Sensor with Sample/Calibration Gas Flow Adaptor
1. Shut off the sample ow to the Flow Adaptor.
2. Disconnect the input pipeline from the input nozzle of the Flow Adaptor.
3. Using the rubber tubing, connect the test gas to the Flow Adaptor input
nozzle.
4. Set the ow rate to 0.5 ± 0.2 liters per minute and test the system in
accordance with the instructions in the appropriate system equipment
manual.
5. On completion, shut off the test gas and disconnect the rubber tubing.
6. Reconnect the input pipeline to the Flow Adaptor input nozzle and restore
the sample ow.

MPD Operating Manual
20
7. Calibration
CAUTION
The calibration procedure should only be performed by qualified personnel.
NOTe:
Honeywell Analytics recommends that the maximum calibration interval
be 6 months or in accordance with customer site procedures, whichever
is sooner to assure the highest level of safety. Correct operation of each
sensor/detector should be confirmed with test gas of known concentration
before each use.
7.1 Zero and Span Calibration for MPD Sensors with XNX Universal
Transmitter
CAUTION
Before initial calibration allow the detector to stabilize for 30 minutes after
applying power. When in zero and span calibration mode the current output from
the detector is inhibited (e.g. default 2mA) to avoid false alarms.
Extended or frequent exposure to elevated concentrations of combustible gases
may affect sensor sensitivity. Verify sensor performance by frequent calibration.
This section describes how to calibrate MPD sensors tted to the XNX Universal
Transmitter.
The calibration adjustments are made on the XNX’s display and gassing is performed
at the sensor (this may be locally or remotely located).
The following equipment is required:
• Sample/Calibration Gas Flow Adaptor (Part No: 1226A0411)
• Test gas
• Regulator
NOTe
Zero gas and Span gas should be at roughly the same humidity levels to
avoid erroneous cell responses.
1. At the MPD, remove the Weatherproof Cap if equipped.
2. Fit the Flow Adaptor onto the MPD.
Figure 10. Flow Adaptor
Reverse the cap removal procedure. The following diagram shows the Flow Adaptor
accessory tted to the MPD.