Installation of Electrical Equipment in Hazardous Areas of Bently Nevada System

Installation of Electrical Equipment in Hazardous Areas of Bently Nevada System

This is intended to provide general information about hazardous areas and how to correctly apply Bently Nevada machinery information systems. Recommendations listed within this document are based on definitions and guidelines established by the North American Electrical Codes, IEC, European, and other agencies throughout the world. Since most field installations vary depending upon the type of hazardous area and the category of equipment to be placed in the area, a careful examination must be made of which equipment is suitable for the area prior to equipment protection. The system design work is completed first, thus allowing proper selection of transducers and electrical equipment with appropriate agency approvals before hardware installation begins.

When practical, electrical systems and instruments should be installed in areas having non-hazardous atmospheres to avoid the possibility of electrical ignition of a hazardous atmosphere. However, theses systems must frequently be installed in locations where flammable or explosive atmospheres exist. Such environments are found in chemical plants, petroleum refineries and other industries where combustible liquids, gases, or vapors exist.

In explosive atmospheres, the instrumentation system must be configured to prevent or control system-caused ignition of the atmosphere. This Applications Note outlines typical hazardous environments in which machinery protection instruments may be installed, ignition-related characteristics of the instrumentation and various safety measures that may be employed to prevent or control ignition.

The material in this discussion is intended to familiarize the reader with types of hazardous area problems and solutions but does not present specific instructions and safety code requirements necessary to install a complete instrument system. For additional data required to design and install an instrument system in such areas, you may refer to publications listed in the appendix of this paper, the instrument manufacturer and/or the local safety or code enforcement agency. The final authority on what is and is not a safe equipment installation rests with the “Safety Enforcement Authority” for that area. This authority may be a representative of the insurance underwriters, a local government inspector or a member of the corporate safety organization.

Prior to instrumentation system installation, the user must determine whether system components will be located in atmospheres that can burn or explode. The degree of hazard must be classified for various areas. These tasks generally fall to the local plant authority. The instruments and wiring to be installed in the area must be evaluated as to their ignition capability. Then, with respect to instrument location, necessary protection measures must be determined for the installation. In all cases, the user must specify the Zone, Group or Class, Division, Group, where the transducers, and where the monitors are to be located.

Installation of Electrical Equipment in Hazardous Areas has covered some basic levels of applying Bently Nevada equipment. This Applications Note does not cover all aspects of the hazardous area environment nor does it discuss all of the equipment that is permitted in these areas.

When specifying a monitoring system to be placed in a hazardous area, the area must be fully defined before selecting electrical equipment. Once the area is defined, the location of the transducers and the location of the monitors can then be determined. Transducers may be placed into the Zone 1/ Division 1 areas when used with safety barriers or galvanic isolators. Monitoring systems are different. They require approved weatherproof housings for Division 1 having a Type X or Type Y purge set-up as defined by the National Electrical Code, Article 500 or Canadian Electrical Code. Primarily, this promotes use of monitors in Division 2 or Safe areas.

In most European countries, monitors are preferably installed in safe areas except in the UK where they are certified for Zone 2.

In Europe, if a monitor has to go in a Zone 1 area, it has to be certified to a purge system (EExp).

Once the area is defined and the equipment locations are chosen, equipment and approval agency selection can then take place. Generally, the approval agency is determined based on geographic location of the job site and which approvals Bently Nevada has received for various products which are being considered. It is important to be sure that all equipment being placed into the hazardous area is certified and approved by a recognized approval agency such as BASEEFA, SIRA, LCIE, or CSA. These approved products will carry the agency’s sticker and logo on them.

Next, the method of preventing ignition should be decided. Flameproof/Explosion-proof housings, air-purged housings, and intrinsic safety barriers or galvanic isolators are all acceptable ways of containing or limiting the source of ignition. Bently Nevada recommends using intrinsic safety barriers or galvanic isolators over explosion-proof housings whenever possible to limit the energy going into the Division 1/ Zone 1 hazardous area. The use of safety barriers or galvanic isolators has proven to be universally accepted throughout the world because of ease of installation, cost-effectiveness, and the high standard of safety attained by using them. With the arrival of internal safety barriers found in recent Bently Nevada monitoring systems, even more safety, convenience, and cost reduction are realized.

Should your specification call for Bently Nevada electrical equipment in hazardous areas, prepare a worksheet of the installation requirements and then contact your nearest Bently Nevada Sales and Service Office for detailed information and assistance.

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