An intrinsic safety barrier (IS barrier) is an integral part of an intrinsic safety system that prevents fire and explosions in hazardous areas with flammable or explosive chemicals and gases.

The two types of intrinsic safety barriers (or intrinsic barriers) are galvanic isolators and zener barriers. To adhere to safety conditions, zener barriers limit excess voltage and current for the circuit. On the other hand, galvanic isolators isolate the circuit and prevent the unwanted current or voltage from passing through other connected components. Some of the devices that use intrinsic safety barriers are flow meters, current-to-pressure converters and proximity switches.

Some important parameters you must consider before purchasing intrinsic safety barriers are:

1. Maximum voltage and current for the circuit
2. Performance specifications for the safety barrier: operating temperature and number of input and output channels
3. Type of current: AC or DC

Action Steps
The best contacts and resources to help you get it done

Buy a safety barrier from intrinsic barrier manufacturers

Once you understand your requirements, research different intrinsic safety barriers from the manufacturers to find the most suitable safety barrier.

I recommend: Exloc Instruments is an intrinsic barrier manufacturer that offers galvanic isolator IS barriers for a range of circuit currents. Pepperl+Fuchs designs and manufactures automation products including intrinsic safety barriers. Motor Protection Electronics, another intrinsic barrier supplier, offers intrinsic safety relays and pump controllers for water and wastewater applications. Leuze electronic provides safety relays for automobile finishing operations. You can also buy intrinsic safety barriers at Ronan and AMETEK.

Buy a safety barrier from intrinsic barrier distributors or retailers

You can compare different safety barriers, their specifications and prices at distributors' or retailers' websites before buying an intrinsic safety barrier.

I recommend: You can buy intrinsic safety barriers online at TriStar Electronics. You can also browse through the list of intrinsic barrier suppliers at ThomasNet and GlobalSpec.

Buy a specialty or customized intrinsic safety barrier

An intrinsic safety barrier must meet all the requirements for your automation system setup. You can select a customized intrinsic safety barrier if standard products available in the market do not match your requirements.

I recommend: Siemens is a reputable intrinsic barrier supplier that also offers specially engineered zener shunt-diode barrier for equipments installed in hazardous areas. Phoenix Contact is another intrinsic barrier manufacturer that customizes modular safety barriers for equipments in explosive surroundings. Rockwell Automation, a manufacturer of automation products, provides standard as well as customized intrinsic safety barriers under the brand Allen-Bradley. You can order customized safety barriers at Rice Lake, another intrinsic barrier supplier.

Tips & Tactics

Helpful advice for making the most of this Guide

• •  Install an intrinsic barrier in a dust and moisture-free enclosure.
• •  As zener safety barriers ground the unwanted current and voltage, ensure isolated grounding when you use them.