Siemens Maxum II User manual

Maxum II
PD PA AP
Explosion Protection Safety
Standards
Manual
August 2017
A5E02220442001 Rev 8
General Information for the
User 1
Safety Systems - Purging 2
Safety Systems - Oven 3
Valves, Detectors, and
External Systems 4
Safe Operation 5

Legal information
Warning notice system
This manual contains notices you have to observe in order to ensure your personal safety, as well as to prevent
damage to property. The notices referring to your personal safety are highlighted in the manual by a safety alert
symbol, notices referring only to property damage have no safety alert symbol. These notices shown below are
graded according to the degree of danger.
DANGER
indicates that death or severe personal injury will result if proper precautions are not taken.
WARNING
indicates that death or severe personal injury may result if proper precautions are not taken.
CAUTION
indicates that minor personal injury can result if proper precautions are not taken.
NOTICE
indicates that property damage can result if proper precautions are not taken.
If more than one degree of danger is present, the warning notice representing the highest degree of danger will be
used. A notice warning of injury to persons with a safety alert symbol may also include a warning relating to property
damage.
Qualified Personnel
The product/system described in this documentation may be operated only by personnel qualified for the specific
task in accordance with the relevant documentation, in particular its warning notices and safety instructions. Qualified
personnel are those who, based on their training and experience, are capable of identifying risks and avoiding
potential hazards when working with these products/systems.
Proper use of Siemens products
Note the following:
WARNING
Siemens products may only be used for the applications described in the catalog and in the relevant technical
documentation. If products and components from other manufacturers are used, these must be recommended or
approved by Siemens. Proper transport, storage, installation, assembly, commissioning, operation and
maintenance are required to ensure that the products operate safely and without any problems. The permissible
ambient conditions must be complied with. The information in the relevant documentation must be observed.
Trademarks
All names identified by ® are registered trademarks of Siemens AG. The remaining trademarks in this publication
may be trademarks whose use by third parties for their own purposes could violate the rights of the owner.
Disclaimer of Liability
We have reviewed the contents of this publication to ensure consistency with the hardware and software described.
Since variance cannot be precluded entirely, we cannot guarantee full consistency. However, the information in
this publication is reviewed regularly and any necessary corrections are included in subsequent editions.
Siemens AG
Division Process Industries and Drives
Postfach 48 48
90026 NÜRNBERG
GERMANY
Document order number: A5E02220442001
Ⓟ 09/2017 Subject to change
Copyright © Siemens AG 2017.
All rights reserved

Table of contents
1 General Information for the User..................................................................................................................7
1.1 Contacts.................................................................................................................................10
1.2 Approved Use........................................................................................................................11
1.3 Qualified Personnel................................................................................................................11
1.4 Applicable Standards and Regulations..................................................................................12
1.5 Safety Protection Principles...................................................................................................13
1.6 Intrinsically Safe Devices.......................................................................................................14
2 Safety Systems - Purging...........................................................................................................................17
2.1 Purging Overview...................................................................................................................17
2.2 Electronics Purging System (without Automatic Purge Unit).................................................18
2.2.1 Overview................................................................................................................................18
2.2.2 Instrument Air Inlet and Regulator.........................................................................................20
2.2.3 Fast Purge Switch..................................................................................................................21
2.2.4 Purge Control Module............................................................................................................23
2.2.5 SYSCON or CIM and Purge Alarm Light...............................................................................23
2.2.6 Pressure Sensor and Atmospheric Pressure Reference.......................................................24
2.2.7 Fast Purge Pressure Relief Valve..........................................................................................25
2.3 Electronics Purging System (with Automatic Purge Unit)......................................................26
2.3.1 Overview................................................................................................................................26
2.3.2 Purge Air Inlet and Regulator.................................................................................................27
2.3.3 Proportional Valve..................................................................................................................28
2.3.4 Automatic Purge Control Unit.................................................................................................28
2.3.5 Maintenance Switch...............................................................................................................29
2.3.6 Exhaust Diffuser.....................................................................................................................30
2.3.7 Signal Disconnect Relay........................................................................................................31
2.4 Maintenance Considerations for Purged Systems.................................................................32
3 Safety Systems - Oven...............................................................................................................................35
3.1 General Oven Information......................................................................................................35
3.2 Isothermal Air Bath Oven Heater System (Single and Split)..................................................36
3.2.1 Purging...................................................................................................................................36
3.2.2 Temperature Control..............................................................................................................37
3.3 Programmed Temperature Air Bath Oven Heater System (Split)..........................................38
3.4 Isothermal Airless Oven Heater System (Split)......................................................................39
3.5 Maintenance Considerations for Air Bath and Airless Ovens................................................41
3.6 Modular Oven Heater System................................................................................................42
3.7 Maintenance Considerations Modular Ovens........................................................................43
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4 Valves, Detectors, and External Systems..................................................................................................45
4.1 Heated Siemens Liquid Injection Valve (SLIV)......................................................................45
4.1.1 SLIV Functional Description...................................................................................................45
4.1.2 SLIV Maintenance Considerations.........................................................................................46
4.2 Detectors................................................................................................................................47
4.2.1 Detector Functional Descriptions...........................................................................................47
4.2.2 Detector Maintenance Considerations...................................................................................48
4.3 Air Treater..............................................................................................................................52
4.3.1 Air Treater Functional Description..........................................................................................52
4.3.2 Air Treater Maintenance Considerations................................................................................53
4.4 Methanator.............................................................................................................................53
4.4.1 Methanator Functional Description........................................................................................53
4.4.2 Methanator Maintenance Considerations..............................................................................55
5 Safe Operation...........................................................................................................................................57
5.1 Maintenance Panel Functional Description............................................................................57
5.2 Maintenance Considerations for Maintenance Panel.............................................................58
5.3 Color Touchscreen Display Functional Description...............................................................58
5.4 Maintenance Considerations for Control Interface Module Display.......................................59
5.5 Steps for Safe Startup of Maxum II........................................................................................60
5.5.1 Overview................................................................................................................................60
5.5.2 Procedure...............................................................................................................................60
Glossary.....................................................................................................................................................63
Figures
Figure 1-1 Reference of Hardware (MAA) to Applicable Sections of this Manual..........................................8
Figure 1-2 Reference of Hardware (MMO) to Applicable Sections of this Manual.........................................8
Figure 2-1 Electronics Pressurization System (Type py) for Airbath/Airless Oven Model (New pressure
relief valve configuration)............................................................................................................18
Figure 2-2 Electronics Pressurization System (Type py) for Airbath/Airless Oven Model (Old pressure
relief valve configuration)............................................................................................................19
Figure 2-3 Electronics Pressurization System (Type py) for Modular Oven Model......................................19
Figure 2-4 Instrument Air Inlet and Pressure Regulator...............................................................................20
Figure 2-5 Fast Purge Switch (Shown in the Off Position)...........................................................................22
Figure 2-6 Purge Control Module.................................................................................................................23
Figure 2-7 Purge Alarm Indicator Lamp........................................................................................................23
Figure 2-8 Pressure Sensor on PECM Board...............................................................................................24
Figure 2-9 Atmospheric Pressure Reference for Purge................................................................................24
Figure 2-10 Pressure Relief Valve for PY Purge............................................................................................25
Figure 2-11 APU System Component Layout (Modular Oven model)............................................................26
Figure 2-12 Purge Air Inlet and Pressure Regulator.......................................................................................27
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Figure 2-13 Proportional Valve.......................................................................................................................28
Figure 2-14 Automatic Purge Control Unit (APU) shown in Airless/Airbath model.........................................29
Figure 2-15 Location and Close-Up of Maintenance Switch (MAA, Set for Normal Operation).....................30
Figure 2-16 MMO APU Maintenance Switch..................................................................................................30
Figure 2-17 Covered Purge Exhaust Diffuser.................................................................................................31
Figure 2-18 Signal Disconnect Relays............................................................................................................32
Figure 2-19 Purge Disable Jumper on PECM or PECM-DC (Shown with Alarm Disabled)...........................33
Figure 3-1 Pressure Switch for Purge Control Module.................................................................................36
Figure 3-2 Timing Coil for Pressure Switch..................................................................................................37
Figure 3-3 Programmed Temperature Air Bath Oven (with Deflector).........................................................38
Figure 3-4 Airless Oven................................................................................................................................39
Figure 3-5 Location of Temperature Probes and Heaters on Airless Oven..................................................40
Figure 3-6 Heat Retainer Plug for Airless Oven...........................................................................................40
Figure 3-7 Typical Modular Oven Configuration...........................................................................................42
Figure 3-8 Heater and RTD Tubes for the Modular Oven............................................................................43
Figure 4-1 Siemens Liquid Injection Valve...................................................................................................45
Figure 4-2 Siemens Liquid Injection Valve (Installed)...................................................................................46
Figure 4-3 Heater for Siemens Liquid Injection Valve..................................................................................46
Figure 4-4 Explosion Proof/Flameproof Thermal Conductivity Detector.......................................................49
Figure 4-5 Thermal Conductivity Detector Beads on Modular Oven Application Module (Intrinsically
Safe TCD)...................................................................................................................................50
Figure 4-6 Flame Ionization Detector (without Insulation and Cover)...........................................................51
Figure 4-7 Flame Photometric Detector (without Insulation and Cover).......................................................51
Figure 4-8 Air Treater...................................................................................................................................52
Figure 4-9 Purged Methanator......................................................................................................................54
Figure 4-10 Explosion Proof Methanator........................................................................................................55
Figure 5-1 Maintenance Panels - Color Touchscreen (left) and legacy HMI (right)......................................57
Figure 5-2 Color Touchscreen Display.........................................................................................................59
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6Manual, August 2017, A5E02220442001 Rev 8

General Information for the User 1
The Maxum II Process Gas Chromatograph employs several design and construction features
which conform to various international safety standards. These standards are to ensure that
the Maxum II and related products can be safely installed and operated in hazardous areas.
Each individual detail and component of these safety systems is important to help ensure that
the chromatograph does not ignite flammable vapors and gases which may be present in the
environment surrounding the analyzer. Therefore, it is important that any personnel that come
in contact with the analyzer be familiar with the operation of the safety systems so that they
are less likely to compromise safe operation while performing routine maintenance, operation,
or other tasks.
This manual provides an overview and general description of the primary safety systems used
in the Maxum II. Also, this manual provides guidelines and procedures that should be followed
to avoid damage to the safety systems. Note, it is not possible in this manual to describe every
possible operation or maintenance situation. At all times, maintenance and operation should
be performed only by properly trained and experienced personnel who are familiar with
explosion prevention designs in electrical apparatus. In addition, Maxum II maintenance and
operation procedures should be supervised and approved by plant personnel who are
knowledgeable in local safety regulations and practices.
Also, this manual does not provide specific instructions for installation, operation, or
maintenance. Those topics are covered in other manuals.
The exact configuration of any Maxum II Process Gas Chromatograph depends on the
application. Therefore, the information in this manual is general in nature and may not apply
to specific installations.
This manual includes figures and illustrations that are not formal design drawings to explain
maintenance issues and device function. Note however, that formal design drawings of all
safety systems are an integral part of the safety certifications for the Maxum II.
This manual describes the safety systems in several sections that relate to the various portions
of the hardware. In addition, a special section is provided to describe normal, safe instrument
startup.
Figure 1-1 for the Maxum Airless/Airbath configuration (MAA), and Figure 1-2 for the Maxum
Modular Oven configuration (MMO), identify the layout of the safety systems of the Maxum II
and associate various portions of the hardware to the relevant sections in this document. Note
that some hardware, such as the Automatic Purge Unit (APU), may be optional depending on
configuration.
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Manual, August 2017, A5E02220442001 Rev 8 7

Heated Valve
Section 4.1
Air Treater
Section 4.3
Detector Enclosure (Including
Detectors and Methanator)
Sections 4.2, 4.4, 4.5
Oven Enclosure
(Air Bath Oven Shown)
Sections 3.1 to 3.5
Electronics
Enclosure (Purged)
Sections 2.2, 2.3
Signal Disconnect
Relay for APU
Section 2.3
Purge Air Inlet &
Regulator
Sections 2.2, 2.3
Exhaust Diuser
Sections 2.2, 2.3
Automatic Purge Unit (APU)
or Pressure Relief Valve
(Inside Enclosure)
Sections 2.2, 2.3
Touch Screen or
Maintenance Panel
Section 5.1
Proportinal Valve for
APU (Section 2.3) or
Purge Control Module
(Section 2.2)
Figure 1-1 Reference of Hardware (MAA) to Applicable Sections of this Manual
Signal Disconnect
Relay for APU
Section 2.3
CIM Display
Section 5.1
Oven Enclosure
for Modular Oven
Sections 3.6 to 3.7
Electronics
Enclosure (Purged)
Sections 2.2, 2.3
Intrinsically Safe
Detector Personality
Module (DPM)
Section 4.2
Automatic Purge Unit (APU)
or Pressure Relief Valve
(Inside Enclosure)
Sections 2.2, 2.3
Exhaust Diffuser
Section 2.2, 2.3
Purge Control Module
(Section 2.2)
Proportinal Valve for
APU (Section 2.3)
edition II
MAXUM
Figure 1-2 Reference of Hardware (MMO) to Applicable Sections of this Manual
General Information for the User
Explosion Protection Safety Standards
8Manual, August 2017, A5E02220442001 Rev 8

See also
Fast Purge Pressure Relief Valve (Page 25)
Copyright Notice
Contents copyright © 2017 by Siemens AG.
All rights reserved.
This publication is for information only. The contents are subject to change without notice and
should not be construed as a commitment, representation, warranty, or guarantee of any
method, product, or device by Siemens.
Reproduction or translation of any part of this publication beyond that permitted by Sections
107 and 109 of the United States Copyright Act without the written consent of the copyright
owner is unlawful.
Trademarks
All names identified by ® are registered trademarks of Siemens AG. The remaining trademarks
in this publication may be trademarks whose use by third parties for their own purposes could
violate the rights of the owner.
General Information for the User
Explosion Protection Safety Standards
Manual, August 2017, A5E02220442001 Rev 8 9

1.1 Contacts
Register at the Siemens Industry Online Support (SIOS) website:
https://support.industry.siemens.com
International USA
Siemens AG
I IA SC PA PM Process Analytics
Oestliche Rheinbrueckenstrasse 50
76187 Karlsruhe
Germany
Tel: [phone]
Fax: [phone]
Web site: www.siemens.com/processanalytics
Training
Tel: [phone]
Email: [email protected]
Spares
Contact your local Siemens sales representative
Support
www.siemens.com/automation/support-request
Tel: [phone]
Siemens Industry, Inc.
5980 West Sam Houston Parkway North
Suite 500
Houston, TX 77041
USA
Tel: [phone]
Fax: [phone]
Email: [email protected]
Web site: www.usa.siemens.com/pa
Training
Tel: [phone] (USA)
Email: [email protected]
Spares
Tel: [phone] (USA)
Tel: [phone] (International)
Email: [email protected]
Support
www.siemens.com/automation/support-request
Tel: [phone] (USA)
Tel: [phone] (International)
Email: [email protected]
Singapore Online Support Request
Siemens Pte. Limited
I IA SC Process Analytics
9 Woodlands Terrace
Singapore 738434
Tel: [phone]
Fax: [phone]
E-mail: [email protected]
Web Site: http://www.siemens.com.sg
Web site:
www.siemens.com/automation/support-request
General Information for the User
1.1 Contacts
Explosion Protection Safety Standards
10 Manual, August 2017, A5E02220442001 Rev 8

1.2 Approved Use
The Maxum edition II gas chromatograph is primarily used in all branches of the fine chemicals,
refining, and hydrocarbon processing industries. It performs chemical composition analysis of
gases and liquids that are present in all phases of production. The Maxum II is built for
installation in harsh environments either directly or nearby in at-line process measurement
laboratories. The application flexibility of the Maxum II allows it to analyze a wide variety of
samples including feedstock, partially processed streams, final products, and process
byproducts including wastes and environmental hazards.
The Maxum II product is intended to be used only in conjunction with other devices and
components which have been recommended and approved by Siemens. Appropriate safety
standards were used in the development, manufacture, testing, and documentation of the
Maxum II. Under normal operation, this product is safe for use providing that all safety and
handling guidelines are observed with respect to configuration, assembly, approved use, and
maintenance. This device has been designed such that safe isolation is guaranteed between
high and low voltage circuits. Low voltages which are connected must also be generated using
safe isolation.
If any part of the Maxum II is opened, certain parts of the device are accessible which may
carry dangerous voltages. Therefore, only suitably qualified personnel may work on this device
as indicated in the next section which is titled "Qualified Personnel".
1.3 Qualified Personnel
Only suitably qualified personnel may operate or perform maintenance on the Maxum II. For
the purposes of safety, qualified personnel are defined as follows:
● Those who have been appropriately trained for the tasks which they are performing (for
example, commissioning, maintenance, or operation).
● Those who have been appropriately trained in the operation of automation technology
equipment and are sufficiently acquainted with Maxum II documentation.
● Those who are familiar with the safety concepts of automation technology and are
sufficiently acquainted with Maxum II documentation.
● Those who are authorized to energize, ground, and tag circuits and devices in accordance
with established safety practices may perform the tasks for which they are trained.
WARNING
Operation or Maintenance of the Maxum II by unqualified personnel or failure to observe the
warnings in this manual or on the device may lead to severe personal injury and/or extensive
property damage.
General Information for the User
1.3 Qualified Personnel
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Manual, August 2017, A5E02220442001 Rev 8 11

1.4 Applicable Standards and Regulations
When proper precautions are observed, the Maxum II Process Gas Chromatograph is
designed for safe use in locations rated as ATEX Zone 1 or Zone 2, or Class I Division 1 or
Division 2. Local safety and electrical codes must be observed for installation, operation, and
maintenance of the Maxum II.
No work should be done on an analyzer without the consent and approval of all applicable
safety authorities. This may include obtaining necessary work permits (e.g. "hot work" permit).
Any changes may affect safety certifications.
An analyzer should never be installed or operated in a location that is more hazardous than
that for which the analyzer was designed. This includes the temperature class, which is also
called the T‑Rating. For reference purposes, table 1-1 lists the applicable Maxum II
temperature limits for areas rated T1 to T4. Refer to section 3.1 (General Oven Information)
for more information regarding temperature constraints for the Maxum II.
Temperature Classifi‐
cation
Surface Temperature
Limit °C
Agency - Approved, Safe Operating Temper‐
ature Limit*
°C
T1 450 440
T2 300 290
T3 200 195
T4 135 130
*Note the maximum operating temperature limit that is approved by the certifying agencies is lower
than the specified ignition temperature limit of the area classifications.
Note: The Modular Oven Configuration always operates below 100°C, and can thus be installed in all
T-rated locations down to T4.
The Maxum II Process Gas Chromatograph conforms to ATEX directive 94/9/EC for safe use
in ATEX Zone 1 or Zone 2 environments.
The ATEX certificate for the Airbath/Airless Oven Configuration is ISSeP10ATEX033X and
comes with the following conditions for safe use:
● The material will be equipped with cable entries of a suitable type ATEX / Ex e.
● The display may resist impact up to 2 Joules.
● It is the manufacturer's responsibility to choose the correct value of resistance for the
determination of the temperature class.
The ATEX certificate for the Modular Oven Configuration is Sira 12ATEX1260X and comes
with the following conditions for safe use:
● The Maxum II Modular Oven Gas Chromatograph shall be fitted with cable glands or conduit
entries having an IP54 minimum rating.
● The Maxum II Modular Oven Gas Chromatograph shall contain shunt zener diode interfaces
that are connected to the external earth stud. This shall be connected to a suitable
intrinsically safe earth in accordance with EN 60079-14:2007 clause 12.2.4.
General Information for the User
1.4 Applicable Standards and Regulations
Explosion Protection Safety Standards
12 Manual, August 2017, A5E02220442001 Rev 8

Typical ATEX Certification Markings for Maxum II
with Airless/Airbath Oven
Typical ATEX Certification Markings for Maxum II
with Modular Oven
1.5 Safety Protection Principles
Several different types of protection principles are used within the Maxum II and its
components. These include intrinsically safe circuits, pressurization, explosion-proof
enclosures, etc. The protection principles used depend on such factors as the type of device,
the certifying organization that is applicable for the site, and the type of environment. Table
1-2 details some of the protection principles used in the Maxum II along with the hardware that
uses those protection principles.
Type of Protection Principle Applicable Devices Applicable Certificate
Intrinsic Safety ● Programmed Temperature
Oven Heater.
● Color Touchscreen
● Intrinsically Safe TCD DPM
CSA & ATEX
Type X Pressurization (Px) ● Electronics Enclosure (EC)
● Liquid Injection Valve Heater*
● Purged Methanator*
● Air Bath Oven Heater
● Modular Oven Heater*
ATEX for the EC, Methanator, and
LIV Heater, and Modular Oven
Heater
ATEX and CSA for Air Bath Oven
Heater
General Information for the User
1.5 Safety Protection Principles
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Type of Protection Principle Applicable Devices Applicable Certificate
Type Y Pressurization (Py) ● Electronics Enclosure (EC)
● Liquid Injection Valve Heater*
● Purged Methanator*
● Modular Oven Heater*
CSA and ATEX
Flameproof Housing ● Flame Ionization Detector
● Flame Photometric Detector
● Thermal Conductivity Detector
(with Explosion-Proof/
Flameproof Housing)
● Airless Oven Heater
● Air Treater
● Methanator
ATEX
Explosion Proof Housing ● Flame Ionization Detector
● Flame Photometric Detector
● Thermal Conductivity Detector
(with Explosion-Proof/
Flameproof Housing)
● Airless Oven Heater
● Air Treater
● Methanator
CSA
* Note: Although the Purged Methanator is located in the Detector Enclosure and the Liquid Injection
Valve Heater is located in the Maxum oven, they are connected in such a way that the interior of these
components are effectively part of the Electronics Enclosure (EC). As a result, they are part of the same
purging system as the EC. This is also true for the heaters for the Modular Oven, which are connected
in such a way that they are effectively part of the EC.
Table. 1-2: Safety Protection Methods in the Maxum II
1.6 Intrinsically Safe Devices
Intrinsic safety is a method of protection where a circuit is designed such that it will not create
a spark or other condition capable of causing ignition of flammable vapors or gases, even
under fault conditions. Various circuits in the Maxum analyzer utilize this form of protection,
including the IS‑TCD and the connections to the CIM touch screen display.
Intrinsic safety protection for circuits and devices within the Maxum II enclosure is designed
to conform to IEC EN60079-11. This is the standard that is applicable to factory installed
electrical components and also for circuits that are additionally protected by other methods,
such as a purged Maxum enclosure.
Because internal Maxum II connections are factory installed wiring, certain labeling techniques
that are commonly seen with intrinsically safe circuits are not applicable. Notably blue
connectors and wiring that the user may be familiar with are not used.
General Information for the User
1.6 Intrinsically Safe Devices
Explosion Protection Safety Standards
14 Manual, August 2017, A5E02220442001 Rev 8

CAUTION
Failure to adhere to the instructions and requirements below could violate the safety
protections of the analyzer.
Maintenance Considerations for Intrinsically Safe Devices:
● Maintenance for intrinsically safe devices, such as the IS-TCD, is limited to replacement.
Repair or service on-site are not permitted.
● Intrinsically safe devices in the Maxum II that are equipped with a cover must have the
cover attached during use. Leaving the cover off can violate requirements pertaining to
mandatory separation from non-IS wiring.
● Intrinsically safe devices in the Maxum II must be operated with all factory installed
mounting and grounding hardware secured. IS circuitry within the Maxum requires two
redundant chassis grounds. There are two separate grounding connections from the CIM-
Base and the IS-TCD to the chassis. Note that redundant grounds from the same device
may not be stacked on the same termination point, but grounds from different devices (such
as CIM and IS-TCD), may share a termination point.
● Care must be taken to prevent other wiring from contacting the IS circuitry. This means that
other all wiring that is secured must remain secured. If it becomes necessary to unsecure
wiring for maintenance, then the wiring must be secured again before placing the equipment
back in service.
● External wiring includes serial cabling, Ethernet cabling, external IO wiring, external power,
and any other wiring that enters the Maxum enclosure from outside. For the installation of
any external wiring, the wiring must be secured in a minimum of two locations, within 50mm
of its termination point and also within 100mm of its termination point. Additionally, secure
along its length as needed to prevent it possibly coming within 50mm of any IS circuitry.
● Any wiring that is not sufficiently secured per the above requirement must have sufficient
insulation thickness to add up to at least 1mm of solid insulation, 2mm of encapsulation, or
remain on the opposite side of a suitable physical barrier from any IS circuit.
● The Maxum chassis is required to be earth grounded at the location where it is installed
using ground screws connected externally as described in the Maxum Installation Manual
(2000595‑001). The earth ground used must be as close to the Maxum as possible.
● Power system ground, from mains power that is brought to the Maxum, is required to be
grounded to the cabinet as part of required installation practices for basic safety.
General Information for the User
1.6 Intrinsically Safe Devices
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General Information for the User
1.6 Intrinsically Safe Devices
Explosion Protection Safety Standards
16 Manual, August 2017, A5E02220442001 Rev 8

Safety Systems - Purging 2
2.1 Purging Overview
For safety purposes, Maxum enclosures that are installed in hazardous locations where
flammable vapors or gases may exist must be purged. Purging refers to the process of
supplying the interior of the enclosure with protective gas in order to increase the pressure
within the enclosure above that of the ambient outside air. This increased pressure creates
flow out of the enclosure and prevents flammable vapors or gases from entering the enclosure.
It also removes any flammable vapors or gases that may exist within the enclosure.
The primary electronic devices of the Maxum II analyzer are housed inside the electronics
enclosure (see Figures 1-1 and 1-2). All electronics in the Maxum II are designed to meet North
American Division 2 and European Zone 2 safety requirements. This means that these
electronics will not cause combustion of flammable vapors or gases under normal conditions.
However, safety codes also require that equipment be designed to accommodate abnormal
conditions as well as normal conditions. The concern is that electronics inside an enclosure
might fail, causing a hot spot, a spark, or some other possible source of ignition. To mitigate
this risk, when operating in locations where flammable vapors or gases are present, the
enclosure is normally closed and supplied with a flow of clean instrument air. The air ensures
that the interior of the enclosure is maintained at a positive pressure relative to the outside and
that air always flows out of, rather than into, the electronics enclosure. This "purging" makes
sure any flammable vapors or gases located outside the enclosure cannot migrate to the
interior of the enclosure where they might contact a possible source of ignition.
The type of purging within the Maxum II depends on location-specific requirements. The
certification of the analyzer (and hence the applicable purging method) can be identified from
the labeling on the analyzer. See Section 1.7 ( Applicable Standards and Regulations ) of this
document for more information. There are two purging methods available in the Maxum II.
1. Purging without Automatic Purge Unit: This is the standard purging method for the Maxum.
In this purging method, constant purging pressure is applied. Circuitry on the Power Entry
Control Module (PECM or PECM-DC, depending on configuration) of the Maxum II is used
to verify positive purging pressure. This circuitry compares interior pressure to exterior
pressure to determine whether the proper pressure difference exists. An alarm is generated
when purge pressure is lost.
2. Purging with Automatic Purge Unit control: This optional method of purging utilizes a device,
called an Automatic Purge Unit (APU), to control the purging system. The APU disconnects
electrical power to the Maxum if purge is lost.
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Manual, August 2017, A5E02220442001 Rev 8 17

2.2 Electronics Purging System (without Automatic Purge Unit)
2.2.1 Overview
The standard purging system of the Maxum II is controlled by the Power Entry Control Module
(PECM) and the processor board (either SYSCON or CIM, depending on the Maxum II
configuration). In the standard purging configuration, an alarm is generated whenever purging
pressure is lost. This is referred to as purging with Type Y pressurization (py). An illustration
of the typical py system of the Maxum II is shown in the following figures.
Legend
“Fast Purge” Switch
Instrument Air
Input - “Clean
and Dry”
Purge
Warning
Light
Air
Regulator
Purge Signal
Cable
PECM to
SYSCON
Pressure
Relief
Valve
Power Entry
Control Module
(PECM) Pressure Sensor
System Controller
(SYSCON)
“Fast” Purge Air Flow
“Normal” Purge Air Flow
Purge Control
Module (PCM)
Electronics
Enclosure
Detector
Compartment
Inside Electronics Enclosure
Purge
Figure 2-1 Electronics Pressurization System (Type py) for Airbath/Airless Oven Model (New
pressure relief valve configuration)
Safety Systems - Purging
2.2 Electronics Purging System (without Automatic Purge Unit)
Explosion Protection Safety Standards
18 Manual, August 2017, A5E02220442001 Rev 8

Legend
“Fast Purge” Switch
Instrument Air
Input - “Clean
and Dry”
Purge
Warning
Light
Air
Regulator
Purge Signal
Cable
PECM to
SYSCON
Pressure
Relief Valve
Power Entry
Control Module
(PECM) Pressure Sensor
System Controller
(SYSCON)
“Fast” Purge Air Flow
“Normal” Purge Air Flow
Purge Control
Module (PCM)
Electronics
Enclosure
Detector
Compartment
Inside Electronics Enclosure
Purge
Figure 2-2 Electronics Pressurization System (Type py) for Airbath/Airless Oven Model (Old pressure
relief valve configuration)
“Fast Purge” Switch
Instrument Air
Input - “Clean
and Dry”
Purge Warning
Light (outside door)
Air Regulator
Purge Signal
Cable PECM-DC
to CIM-Board
PECM-DC
(back wall of enclosure) Pressure
Reference
Purge Control
Module (PCM)
Electronics
Enclosure
CIM-Board (inside door)
Modular Oven
Compartment
Legend
“Fast” Purge Air Flow
“Normal” Purge Air Flow
Inside Electronics Enclosure
Pressure Sensor
Purge
Pressure
Relief
Valve
Figure 2-3 Electronics Pressurization System (Type py) for Modular Oven Model
Safety Systems - Purging
2.2 Electronics Purging System (without Automatic Purge Unit)
Explosion Protection Safety Standards
Manual, August 2017, A5E02220442001 Rev 8 19

In this configuration air enters the enclosure through one of two possible paths. A pressure
sensor on the PECM determines whether the pressure inside the enclosure is higher than the
pressure outside the enclosure. If purge pressure is lost, then the PECM sends this status to
the System Controller (SYSCON) or Control Interface Module (CIM), depending on which
processor is used. The SYSCON or CIM generates an alarm message and turns on the Purge
warning light on the front door of the Maxum II analyzer. When purge is operating properly,
excess pressure is released through the pressure relief valve.
Note that PECM in the above descriptions may refer to the PECM or PECM‑DC, depending
on configuration of the Maxum II. The Type Y pressurization purging system consists of the
components described in the following sections.
2.2.2 Instrument Air Inlet and Regulator
This is a pressure regulator with air input that is connected to an instrument air source. The
regulator is necessary to prevent excess input air pressure. Depending on the configuration
of the Maxum II, the regulator may be labeled as either "Purge" or "Isothermal Oven Air" (refer
to the section of this manual regarding Isothermal Ovens for more information). The purge air
is connected to the purged electronics enclosure through two possible paths, the "normal" path
and the "fast purge" path. These flow paths are shown in figures 2-1 and 2-2 and are described
in the following section titled "Fast Purge Switch". All instrument air must be clean (free of
particulates and flammable vapors and gases) and dry.
Figure 2-4 Instrument Air Inlet and Pressure Regulator
Safety Systems - Purging
2.2 Electronics Purging System (without Automatic Purge Unit)
Explosion Protection Safety Standards
20 Manual, August 2017, A5E02220442001 Rev 8