Installation Checklist for Intrinsically Safe Instrument (Apparatus)

Safety and Risk Assessment

Before starting any installation activities, prioritize safety measures to ensure both personnel and equipment protection, especially in hazardous environments:

Risk Assessment:

• Conduct a thorough Hazard and Risk Assessment specific to the installation of intrinsically safe (IS) instruments.
• Identify hazards related to explosive gases, incompatible equipment, or incorrect wiring practices.
• Document control measures to mitigate identified risks and ensure they are applied during the installation.

Safety Procedures:

• Implement Lockout/Tagout (LOTO) procedures to ensure the isolation of power systems.
• Confirm that personnel are equipped with appropriate Personal Protective Equipment (PPE) suitable for hazardous area work, such as flame-resistant clothing and intrinsically safe tools.
• Review and adhere to site-specific safety practices related to working in hazardous areas, especially in classified zones.

Work Permit:

• Ensure all required work permits have been issued, and verify that all safety protocols have been clearly communicated to the installation team.

Pre-Installation Documentation Review

Thoroughly reviewing documentation is critical to a successful installation:

Project Documentation:

• Verify the availability of accurate and up-to-date installation drawings.
• Review the system design drawings to ensure alignment with intrinsic safety requirements and that equipment placement meets hazardous area classifications (Zone 0, 1, or 2).
• Ensure that all necessary certificates (ATEX, IECEx, or other relevant certifications) for the IS apparatus are valid and available.

Equipment Compatibility:

• Check that the apparatus is suitable for the hazardous area classification, ensuring it complies with relevant gas and dust classifications (e.g., Zone 0, Gas Group IIC).
• Confirm that the instrument’s temperature classification is appropriate for the surrounding environment.

Cable Specifications:

• Verify that the cable type and length meet the system’s design specifications, and ensure they are documented in the project files.
• Ensure that the capacitance and inductance of the cables are within the safety parameters of the IS system.

Pre-Installation Preparations

Before starting physical installation, ensure all preparations are complete:

Site Inspection:

• Inspect the installation area to ensure it meets all intrinsic safety requirements.
• Confirm that there are no sources of ignition or environmental hazards that could affect the installation process or equipment operation.

Tools and Equipment:

• Gather all necessary tools, ensuring they are certified for use in hazardous areas and meet IS installation requirements.

Initial Safety Parameters Verification

Check the intrinsic safety parameters of the instrument to ensure compliance with hazardous area requirements:

Protection Levels:

• Verify the instrument’s level of intrinsic safety protection (e.g., ia, ib, or ic) and ensure it matches the system’s requirements.

Gas and Temperature Classification:

• Confirm that the instrument’s gas group classification (e.g., IIC, IIB, IIA) is suitable for the area of installation.
• Check the instrument’s temperature classification to ensure compatibility with the operating environment.

Electrical Parameters:

• Verify that the instrument’s voltage (Uo), current (Io), and power (Po) limits are within the acceptable range for intrinsic safety.
• Confirm that the cable capacitance (Cc) and inductance (Lc) are compliant with IS system limits.
• Ensure the L/R ratio is compliant with the intrinsic safety barrier’s specifications.

Click here for What is a Safety Barrier? & how does Safety Barrier work?

Physical Installation Checks

Ensure the physical installation follows design and safety protocols:

Mounting and Location:

• Ensure the instrument is mounted in the correct location according to the installation drawings.
• Confirm the mounting system provides adequate protection against mechanical stress, vibration, and environmental factors such as corrosion or moisture.

Sealing and Glands:

• Verify that cable glands are correctly installed and sealed to prevent the ingress of gases or moisture into the enclosure.
• Ensure enclosures are correctly sealed to maintain their intrinsic safety rating.

Labeling:

• Check that the instrument is properly labeled with the correct intrinsic safety information, including certification markings, classification, and identification tags.

Earthing System Verification

Proper earthing is essential for the safe operation of intrinsically safe equipment:

Earth Connection:

• Verify the integrity of the instrument’s earth connection, ensuring it provides a low-resistance path to ground.

Earthing Scheme:

• Check that the earthing scheme complies with the project’s design requirements and that no multiple earth points exist, which could cause interference or safety issues.

Click here for Instrument Earthing Systems

Cable Screens:

• Ensure that cable screens are properly earthed at designated points to prevent electrical interference.

Surge Protection:

• If applicable, verify that the surge protection system is properly earthed and integrated with the IS system.

Circuit Isolation and Insulation Checks

Ensure the system’s isolation and insulation requirements meet intrinsic safety standards:

Isolation Requirements:

• Verify that all circuit isolation barriers or isolators meet the system’s intrinsic safety requirements.

Insulation Integrity:

• Perform insulation tests using a low-voltage insulation tester to confirm that the instrument and cables are free from any potential insulation degradation.

Separation from Non-IS Circuits:

• Ensure that intrinsically safe circuits are properly separated from non-IS circuits, both physically and electrically, to avoid cross-circuit interference.

Click here for Why Choose Intrinsic Safety (IS) for Hazardous Area Instrumentation?

Functional Testing of Loop with Alarm Trip Logic, ESD, PLC/SCADA, and DCS Integration

After the physical installation, conduct a thorough functional test to ensure system integration and correct operation of the loop:

Loop Testing:

• Perform a complete loop test, verifying that signals from the field instrument reach the control system (PLC, SCADA, or DCS) without distortion or interference.

Alarm Trip Logic Testing:

• Test the alarm trip logic, ensuring that the alarms trigger at the appropriate setpoints and are correctly displayed on the control system interface.

Emergency Shutdown (ESD) Testing:

• Conduct an Emergency Shutdown (ESD) system test to confirm that the IS instrument correctly interacts with the safety systems, and triggers an ESD event when required.

PLC/SCADA Integration:

• Verify the proper integration of the instrument with the PLC and SCADA systems. Confirm that data from the instrument is accurately displayed on SCADA screens and that control commands can be sent back to the instrument if applicable.

DCS Integration:

• For systems integrated with a Distributed Control System (DCS), ensure that the data from the IS instrument is correctly integrated into the DCS architecture, and all alarms, controls, and feedback loops function as designed.

Interference Checks:

• Test for any interference with other systems, ensuring that signal integrity is maintained throughout the communication between the instrument and control systems.

Click here for Why select Intrinsic safety?

Final Operational Checks

Perform additional operational tests to verify the system’s reliability and safety:

Functional Testing:

• Conduct full functional testing of the entire system to ensure that it performs as designed under normal operating conditions.

System Performance:

• Verify that the instrument interacts correctly with control and safety systems, such as PLCs, SCADA, ESD, and DCS, and that all parameters are operating within specified limits.

Documentation and Record Keeping

Accurate record-keeping is essential for future maintenance and compliance audits:

Installation Records:

• Document all installation details, including location, equipment types, and cable parameters.

Deviations:

• Note any deviations from the original design, ensuring these are approved and documented in the project files.

Certificates:

• Store all relevant certificates related to the equipment’s intrinsic safety rating and performance.

Inspection Results:

• Record the results of all tests and inspections performed during installation.

Maintenance Records:

• Document any special maintenance or calibration requirements identified during installation or testing.

Periodic Inspection Planning

Intrinsic safety systems require regular inspection to ensure continued compliance and safe operation:

Inspection Frequency:

• Establish a routine inspection frequency, typically every three years, but potentially shorter based on the risk assessment or operational history.

Inspection Scope:

• Define the scope of periodic inspections, which should include visual inspections, loop tests, and verification of intrinsic safety parameters.

Maintenance Schedule:

• Develop a maintenance schedule to ensure that all IS equipment remains within operational safety limits.

Shortened Intervals:

• Define criteria for shortened inspection intervals, especially for high-risk environments or systems that have experienced failures or issues.

Important Notes in Intrinsically Safe Instrumentation Installation

• All modifications to intrinsically safe systems must be approved and documented. Unauthorized changes can lead to safety hazards.
• Maintain strict separation between IS and non-IS circuits to prevent potential cross-circuit hazards.
• Ensure that personnel performing installation and maintenance are certified and qualified to work with intrinsically safe systems.
• Keep all safety-related documentation, including installation records, inspection logs, and certificates, easily accessible for future reference.

This installation checklist should be part of the overall project execution plan to ensure compliance with safety standards like IEC 60079 and NFPA 70, safeguarding both equipment and personnel in hazardous environments.

Click here for more Essential Instrumentation activities Checklists

Intrinsically Safe Instrumentation Installation Example

The diagram illustrates a typical intrinsically safe (IS) instrument installation for hazardous and non-hazardous areas. It shows how equipment is classified based on the hazardous zone, the safe routing of signals through IS interfaces, and the connection to a control system in a non-hazardous area. The installation is designed to ensure safety in potentially explosive environments, adhering to relevant safety standards (e.g., IEC 60079).

Hazardous Area Zones and Equipment

Zone 0 (IIB T3) – Highest Risk Area

• Description: Zone 0 is a location where an explosive atmosphere is present continuously or for long periods.
• Equipment: A thermocouple is installed here as part of the system. Thermocouples are often classified as simple apparatus because they don’t store or generate significant energy, making them inherently safe.
• Cabling: Cable B01 connects the thermocouple to the rest of the system, ensuring that no unsafe levels of energy enter this zone.

Zone 1 (IIB T3) – Moderate Risk Area

• Description: This zone is where explosive gases are likely to occur in normal operations.
• Equipment:A temperature transmitter is installed here, also marked as a simple apparatus due to its low energy levels.
• Cabling:Cable B04 carries the signal from the transmitter out of the hazardous area.

Zone 2 (IIB T3) – Low Risk Area

• Description: Explosive atmospheres are less likely to occur here and would only be present under abnormal conditions.
• Equipment: A junction box collects signals from devices in Zones 0 and 1, preparing them for routing to the non-hazardous area.
• Cabling: Cable B05 connects the junction box to the interface cabinet in the non-hazardous area.

Interface Area

This is a transition zone where signals pass from the hazardous area to the non-hazardous area through safety barriers.

Intrinsically Safe Interface

• The IS interface is critical as it limits energy passing through the system to ensure that even in fault conditions, energy levels remain below the threshold that could ignite an explosive atmosphere.
• Cable B09 is used to connect the IS interface to the control system in the safe area.

Non-Hazardous Area (Safe Area)

Control System Rack

• This is where the signals from the hazardous area are processed. The control system can be a PLC, SCADA, or DCS.
• The control rack is responsible for monitoring and controlling processes in the hazardous area.
• The diagram shows connections using Cables wire 102, 103, 24V, and 0V, which indicate the inputs, outputs, power, and ground connections for the control system.

Signal Transmission and Safety Measures

Simple Apparatus

• Both the thermocouple and temperature transmitter are classified as simple apparatus, meaning they inherently generate or store low energy levels, making them safe for hazardous areas.

Cabling

• The diagram highlights the use of IS-rated cables (B01, B04, B05) to ensure safe signal transmission. These cables are designed to prevent energy transfer that could trigger ignition in hazardous zones.

Junction Box

• The junction box in Zone 2 plays an important role in consolidating and managing multiple signal lines from hazardous areas, providing a secure point to manage wiring before sending it to the IS interface.

IS Interface

• The intrinsically safe interface limits the electrical energy and ensures that the hazardous area devices remain safe under all operating conditions.

Safety Standards and Zoning Classification

• The equipment and cabling must comply with safety standards such as IEC 60079, which governs the use of electrical equipment in explosive atmospheres.
• Zoning (Zone 0, Zone 1, and Zone 2) and classification of devices (e.g., IIB T3) indicate the level of protection required based on the risk of explosion in those areas.

Click here for IEC Standards Chart for Instrumentation and Control

Key Functional Testing Procedures

Once installation is complete, functional testing ensures that the system operates correctly and safely:

• Loop Testing: Verify the integrity and performance of the complete loop from the thermocouple in Zone 0 through to the control system in the safe area.
• Alarm Trip Testing: Ensure that all alarms function as intended under predefined hazardous conditions, especially in critical areas.
• ESD (Emergency Shutdown) Testing: Confirm that emergency shutdown systems integrated with the IS equipment trigger safely in response to abnormal conditions.
• Integration with SCADA/PLC/DCS: Check that the system integrates properly with SCADA, PLC, and DCS systems, ensuring real-time monitoring and control of processes.

Intrinsically Safe Instrument Installation Checklist (Excel Download)

Ensure a smooth and compliant installation of intrinsically safe instruments in hazardous areas with this comprehensive checklist. It covers key steps for planning, installation, inspection, and testing to ensure safety and adherence to industry standards. Refer the below link to download

Intrinsically Safe Instrument Installation Checklist – Download

FAQ on Intrinsically Safe Instrumentation Installation

what is Simple apparatus?

In the context of intrinsic safety, simple apparatus refers to electrical equipment that is considered not to pose a significant risk of igniting an explosive atmosphere and therefore does not require formal certification. Such apparatus does not store or generate energy in a manner that could produce a spark or high temperature sufficient to ignite a hazardous environment.

The key characteristics of simple apparatus are:

1. Simple apparatus do not have energy-storing components (e.g., batteries, inductors, or capacitors) that could discharge and cause ignition.
2. They typically operate at very low power levels that do not have the potential to ignite an explosive atmosphere.
3. They do not include complex electronic components or circuits that could malfunction and cause a spark.

Because of these characteristics, simple apparatus are exempt from the need for certification under intrinsic safety standards. They are still subject to standards that outline their safe use, and it must be demonstrable that they are safe in hazardous environments.

Common examples of simple apparatus include:

• Switches
• Thermocouples
• Resistance Temperature Detectors (RTDs)
• Junction boxes
• Passive connectors

Although they are exempt from certification, these devices must be used correctly within an intrinsically safe system and must conform to installation requirements specified in the relevant standards

What wiring method should be permitted for installing intrinsically safe apparatus?

For intrinsically safe (IS) apparatus installation, the wiring must adhere to specific safety standards:

• Dedicated IS Cables: Use cables rated for IS circuits, designed to minimize energy transmission.
• Separation: Maintain physical separation between IS and non-IS wiring to prevent accidental energy transfer.
• Conduits and Cable Trays: Use metal conduits or cable trays with proper labeling and separation.
• Grounding: Ensure proper grounding and bonding to prevent static buildup.
• Shielding: Use shielded cables where electromagnetic interference (EMI) is a concern.

What are the requirements for intrinsically safe?

To be considered intrinsically safe, a system or device must meet these key requirements:

• Energy Limitation: The device must limit electrical energy to levels that cannot ignite explosive atmospheres.
• Compliance: Follow standards like IEC 60079 and ATEX to ensure proper design and installation.
• Certified Components: Use certified IS components, including barriers and isolators, for hazardous areas.
• Grounding: Ensure proper grounding to eliminate static risks.

What is intrinsically safe installation?

An intrinsically safe installation involves:

• Hazardous Area Classification: Classify the area based on explosion risks (e.g., Zones 0, 1, 2).
• Use of IS-Certified Equipment: Install only IS-certified devices and barriers.
• Proper Wiring: Use IS-rated wiring and maintain separation from non-IS circuits.
• Grounding and Shielding: Ensure proper grounding and EMI shielding.
• Testing: Conduct functional tests, including loop tests and alarm logic integration with PLC/DCS.

What makes an instrument intrinsically safe?

An instrument is intrinsically safe if:

• Energy Limitation: It limits the electrical energy in its circuits to prevent ignition in hazardous areas.
• IS Barriers: It is connected to energy-limiting IS barriers or isolators.
• Certified Components: It uses certified components and follows relevant IS standards.
• Design: It is designed to prevent sparks or high temperatures that could ignite explosive gases or dust.

Click here for Difference Between Intrinsically Safe and Explosion-Proof