Intrinsic Safety for Hazardous Areas Explained

Intrinsic Safety Barriers are devices that limit power delivered from a safe area into a hazardous area. The possibility of an explosion is prevented, not merely contained (by a housing or a conduit). The total energy is maintained within safe limits, not electrical energy (voltage and current), eliminating an ignition from excessive heat. The use of an intrinsically safe design offer many cost and safety advantages.

• Easy access to components - no time spent opening/closing explosion proof enclosures.
• Safety assured due to low voltage system.
• Use of standard wiring, cable runs, and light gauge cable.
• Calibration and maintenance the same as if in a general purpose area.
• No special hazardous area procedures for opening enclosures, area gas testing, or shut-down process.
• Simple use of plug-in modules.

The document below provides an excellent explanation into Intrinsic Safety and goes far more in to the background, concepts, principles, and devices used in this approach to safety in hazardous areas.

Intrinsic Safety Explained from Belilove Company-Engineers

For more information, contact:

BCE

P.O. Box 55936
21060 Corsair Blvd
Hayward, CA 94545

www.belilove.com
Phone: (510) 274-1990
Fax: (510) 274-1999
E-mail: sales@belilove.com

In the Market for an Industrial Annunciator? Here's a Guide to Help

Alarms and Annunciators

Annunciators are found in industrial control rooms, boiler rooms, power substations and just about any type of process control operations room where the process conditions need to be closely monitored and where constant status indication is important.

Here is an outline for the primary selection criteria for an integrated logic alarm annunciator:

Chassis

• Panel mount
• Surface mount
• Rack mount

Alarm Points

• How many alarm points do you have? Annunciators break down alarm points by "cell" and you call out the number of cells based on the layout desired. For instance, a 1x4 would be 1 annunciator cell tall by 4 cells wide. 

Pushbuttons (and Location)

• Occupying bottom right module cell space
• On the bottom right trim of the chassis
• Located remotely

The Available Panel, Box or Cabinet Space Available

• Dictates how alarm points and pushbuttons are arranged.

Networkable or Stand-alone?

Configuration via software?

Event recording?

Do you need electrical outputs?

• Audible and visual signals: horn, beacon, bell
• Common Trouble Alarm (CTA) Relay: notification of any alarm within the system (commonly used for remote beacon or dial-up) 
• Group CTA functions: for critical and noncritical groups 
• Auxiliary Contact Repeat Relay: individual repeater output per input 
• Reflash Alarm Relay: alarm counter 

Field contact voltage?

Source voltage?

Alarm type grouping? 

For a detailed annunciator selection guide (courtesy of RONAN Engineering) visit this annunciator selection guide link.