What is Class 1 Div 2?
Class 1 Div 2 is a classification of hazardous location. When a location is deemed a hazardous location, it means that the location is at risk for combustion, flammability or an explosion due to the potential presence of flammable vapors or gases. Within this classification, a Class: 1 Division 2 area means an area where: (1) Ignitable concentrations or quantities of flammable gases or vapors are handled, processed, or used; or (2) Ignitable concentrations of flammable gases or vapors are not handled, processed, or used in the area, but where the use of electrical equipment is normally inconducive to the safe conduct of operations because of the hazard of physical damage to the electrical equipment from adjacent operations, outside traffic, etc . In practice, this means that in a Class 1 Div 2 area, electrical equipment within the location may be exposed to flammable or highly flammable materials in the atmosphere, but under normal operating conditions, the flammable materials are contained within an enclosed area.
Importance of Seal Off Requirements
Use of seal-off requirements is very important in a Class 1 Div 2 area as it is meant to make the interior of the cabinet below the EzSeal coupling the same as the exterior of the enclosure above the EzSeal coupling. Electrical code requirements for conductors or cables passing into or out of a Class I Division 2 area are contained in Articles 501.15(A), (B) and (C) of NEC 2014, which also apply to NEC 2015. Article 501.15(A) requires that cable or conductors entering or leaving a Class I Division 2 area have an approved sealing fitting installed in accordance with Articles 501.15(B) and (C).
Article 501.15(B) provides that for fittings used for rigid conduit the seals are installed inside the conduit, except as provided in 501.15(B)(2). Article 501.15(B)(2) provides for an exemption from 501.15(B) to paragraph (B)(1) above to the following: A power distribution panel shall be allowed to be connected for circuits and device feeds that are located in both Class I, Division 1 and Division 2 areas, where the sealing fitting described in Section 501.15(B) is installed at the entrance of the Class I, Division 1 area only. In such a case, the seal shall be properly sized so as to ensure that the minimum distance, as required in Section 501.15(B), is maintained within the Class I, Division 1 area. In such cases, the conductors entering the panel in the Class I, Division 2 area shall be installed in a flexible metal conduit or nonmetallic raceway.
With the use of EzSeal couplings as a replacement for traditional conduit seals, Article 501.15(B)(2) provides a provision for exemption from 501.15(B) for the panel being provided with a non-metallic raceway. The use of a non-metallic raceway (i.e., liquid tight conduit that is not metal) in place of rigid metal conduit provides the same protection as metal conduit for conductors and cables passing through the explosion hazard but will not provide a ground path for the equipment. It is very important that this issue be addressed in the compliance of the equipment to the Class 1 Div 2 area. The connectors that have been developed for use above and below the explosion hazard have an integral jumper or internal ground strap to provide a ground connection if metallic elements of the enclosure are being utilized to ground the equipment.
Seal Off Types
Seal off material is typically a stuffing compound used to seal off the inside gas path under increasing sealing pressures to assure a safe, continuous seal exists at all times. Seal off materials have been developed in various forms, including granular, putty, rope, tape, putty tapes and tubular forms.
Granular seal off material comes in a variety of sizes and compositions to accommodate different applications and pressures. The particle sizes of these systems can range from 20/30 mesh all the way to fine powder. Granular seal off materials are typically utilized when a pack off is built into the flameproof conduit fittings such as a combination seal, or a device where the granular material is placed under high pressure in a tube. Some tubular applications incorporate granular seal off systems in pre-taped tubing (such as mineral insulated cable).
Putty seal off material applications include both powder and semi-paste putties filled to various concentrations with inert solids. Commonly incorporated into conduit within flameproof systems, putties can also be used for sealing cable in various applications. Typical applications include sheaths or wraps applied to a leave behind, or layered applications onto cables in conduit, to promote a high degree of adhesion. Often these putties are applied in lieu of packing material.
Rope type seal off materials are typically twisted, round ropes of a stranded or braided composition. Ropes are often coiled with layers of conventional packing in between, both for applications with small diameter packed off tubes and applications where the rope has been wound around and through cable contact points. Typical applications include poring putty over compacted, flexible packing where an air gap exists following compaction.
Tape seal off materials are used as a pre-tape material or in conjunction with your tubular type offerings. The use of tape can be beneficial during the installation process by improving the ease of placement, enhancing the surface bonding properties, and/or providing a low compression tape. For low compression sheath cables and highly compacted non-compression material applications, the use of tape can enhance the bonding ability of top coats of tape with additional adhesive.
Putty tapes and tubular forms of tape seal off materials enhance the typical capabilities of a conventional tape. Typical applications include use as an interleaved tape in conjunction with other types of seal off materials such as putties or granular material. These compounds offer advantages and benefits of a tape combined with the advantages and benefits associated with putty or granular seal off materials.
Sealing Off Instructions
Once the decision has been made to install seal offs, it is important to ensure that they are being used in the correct locations per the relevant installation standard. For example NEC 500 Method 3 requires the use of seal off fittings at conduits or tubing. Whereas NEC 501 requires the use of an explosionproof fitting with flexible metal conduit for Class 1 Div 2 locations and it does not specify a seal off method. It is always a good idea to refer back to the manufacturer’s instructions for these types of details.
The ANSI/ISA 12.12.01 standard for (10070-2010) standard for wiring and instrumentation specifies that the seal off fittings be installed in such way that any point of gas migration from outside the conduit to the inside of the conduit must pass through the seal off. The standard also states that the interior of the seal off must be filled with a suitable compound so that it is gas tight.
It is very important that the sealing compound not be mixed with any other substances as specified by method 503, such as two part epoxy. Mixing the sealing compound with other substances can actually reduce the protective qualities of the sealing compound. It is important to use the same type of sealing compound for any seal off fittings to ensure proper functioning. If a seal off is damaged it is suggested that the best approach is to restore it to its original condition by the same procedure as before. A common problem is the over filling or under filling of the seal off. If there is not enough sealing compound in the unit, leaking conduits or tubes can cause flashback and have devastating effects. While it is always best to consult the manufacturer’s instructions for the specific equipment you are using, Seal offs should be used to ensure that all seals are concentric with the device inside the enclosure and on exterior mounting surface. It is important to use the same type of compound when making multiple installations as this will allow compatibility in the future next time the equipment is serviced or replaced. Seal off junctions should always be made in an area of minimal vibration. Seal off fittings should not be located near strain relief devices for cable unless it can be known with reasonable certainty that vibration levels are minimal. If seal offs are necessary in close proximity to vibration producing factors, the only practical solution is to use explosionproof fittings.
Regulatory Compliance Issues
Class 1 Div 2 seal off requirements can often be overlooked when a newer electrical code begins to take effect. This can lead to companies being unprepared for the updated code, especially when dealing with Class 1 Div 1 hazardous locations. Another common concern is the difficulty that some companies face when trying to have an internal audit performed for their device entry requirements. They may not be aware of the extent of their obligations, and the number of devices that must be entered outside of their space. However, there are a handful of common problems that can pose compliance roadblocks.
One such problem is that older connections may still be in service from before Class 1 Div 2 seal offs were required (essentially, devices with no internal seals). If a connection goes out at a remote site, it can be difficult for your company to rush its TL 07 audit to submit for approval without facing off against non-compliance penalties. However, as long as you have the documentation showing the original date of installation, "grandfathering" provisions called out in the code state that it is most often acceptable to continue using these obsolete connections . This may only become an issue when the device is replaced or upgraded, and the local authority has verified your plans with their own engineer and found the corporate TL 07 plan to be sufficient. Once that happens, you won’t be able to show your audit plan as readily as the ones you have provided in conjunction with the new devices your company has purchased.
Another road block brought up repeatedly by companies who invite TL 07 audits is that their personnel have been handed the manual for one particular area of the business, and they don’t have full visibility over the entirety of the site. If this is the case, you should add to or supplement the manual with an overview section presenting a complete picture of what exists on the site, and how your plan helps prevent potential compliance issues and the penalties they can lead to.
A final major stumbling block we see at the beginning of a TL 07 audit is a lack of information about hazards that may exist on-site. If your auditor shows up and your personnel cannot tell them about flammable materials in an area, it will raise a red flag and potentially require your management to hire a consultant to gather additional information and get them up to speed.
Seal Off Innovations
Recent developments in seal off technology have focused on improvements in materials and designs that simplify the sealing off process while still ensuring a high degree of protection from gas flow. In some explosive gas environments, a single sealing-off fitting must include multiple taps where different conductors will enter the enclosure without breaching the seal which must be absolute. For a number of years now, one of the main materials used to provide seals has been a type of epoxy resin. This is often injected into the sealing off fitting and allowed to cure in place. However, in many situations it can be difficult to control how far into the fitting the epoxy will flow. Another way to mitigate this problem is to flood the entire fitting with epoxy. However, this can cause difficulty with further electrical work when it can be difficult or impossible to remove the not-yet-cured epoxy from the fitting.
A newer material called Norchem forms a more uniform seal off that does not require as much effort as traditional methods. Norchem does not intrude into the cable space which means that when the seal off is complete it does not significantly impair the ability to use the space. The new chemical is mixed with water to create a slurry that is then poured into the sealing off fitting. This slurry mixes with air to form a tough seal off that can be ready for inspection in a matter of hours. Another benefit of Norchem is that it can be completely removed for future work. The Norchem seal off allows the capping process to move beyond the restriction of a time consuming process that falls into two categories: explosion-proof or non-explosion-proof. These limitations can now be moved around.
Summary
In summary, the Class 1 Div 2 (CI DIV 2) seal off requirement is a critical component of maintaining safety in industrial environments where flammable gases, vapors, or liquids are present. These requirements, as outlined by NFPA 70 (The National Electrical Code), are designed to mitigate the potential for sparking that could lead to disastrous explosions and fires. The C1 DIV 2 seal off requirements are particularly relevant for process instrumentation, including thermowells, where maintenance and repair access is crucial over the life cycle of the product.
Failure to comply with these requirements can pose serious risks. However , proper planning and proactive design can ensure compliance and enhance safety. Investing in CI DIV 2 compliant products and infrastructure will not only bring your operations into compliance with the NFPA 70 requirements but also ensure that you are prepared for the more stringent inspection and certification standards implemented by OSHA.
It is essential for companies operating in hazardous locations to stay abreast of current standards and regulations and to ensure that their facilities and processes are in full compliance. This includes regular reviews of safety procedures, equipment inspections, and updating of systems and procedures as needed.