Explosion Protection: A Short Guide to Selecting the Correct Explosion Panel

Successful venting of an enclosure during deflagration is essential to the safety of all concerned. Providing an adequate vent area is one of the most important factors to be considered when sizing the vent area of an enclosure. The NFPA (National Fire Protection Association) has provided standards and proper sizing equations for relief areas for enclosures.

For example, NFPA 68 states: Deflagration venting is one means of controlling damage. By releasing expanding gases through an opening engineered for that purpose, it is possible to maintain a reduced maximum pressure (Pred) that is below that which would cause unacceptable damage...The choice of the most effective and reliable means for explosion control should be based on an evaluation that includes the specific hazard and objectives for protection.

Many of the applications for explosion panels and the venting of enclosures occur in the processing of grain and the associated dust. Grain dust is a highly explosive media and a natural occurrence in the pneumatic handling and conveying of grain. The NFPA 61 Bulletin Standards for the Prevention of Fires and Dust Explosions in Agricultural and Food Products Facilities provides guidelines for Starch, Grain Elevators, Feed Mills, and Agricultural Commodities.

Useful Definitions

Deflagration: A flame front propagating through unburned media less than the speed of sound (subsonic velocity).
Detonation: A flame front propagating through unburned media greater than the speed of sound (sonic velocity).
Explosion: A point after detonation occurs where the internal pressure exceeds the ultimate strength of the enclosure.
‍Pmax: The maximum internal pressure which the enclosure can sustain.
Pred: The maximum allowable internal pressure the enclosure will experience during a vented deflagration.
Pstat: The designed pressure that the explosion panel opens and venting begins.
Explosion panel: A pressure and temperature sensitive membrane designed to rupture at a predetermined pressure and temperature. Also known as an explosion vent, rupture panel or vent panel.

Common Applications

Dust Collectors & Arrestors
Bucket & Drag Conveyors
Blenders
Mixers
Crushers
Grinders
Pulverizers
Driers
Ovens & Furnaces
Ducts
Bins
Silos
Grain Elevators
... Any application where deflagrations are possible

Selecting an explosion panel

The advantages of using explosion panels over other methods of venting are their economical cost and the fact they provide a leak-tight seal until activation. Factors to consider when selecting an explosion panel for your facility include the following:

Dust type or gas type / composition
Dust Kst value
Curved or flat surface
Normal operating temperature
Maximum temperature
Nominal working pressure
Rupture pressure required (Pstat)
Static or cycling application
Location of the vent (indoors or outdoors)
New or retrofit application
Are vacuum conditions ever present?
Ideal construction material for the explosion panel
Duct length
Volume of vessel or area to be protected
Vent area required - support is available for calculating this, please contact our engineers for further information.

OE’S PRODUCT LINE

OsecoElfab’s explosion panels are dependable and efficient. The composite construction provides strength for static and high vacuum applications. We use laser scoring technology to achieve precision, dependability and repeatability in establishing set rupture pressures. The finished product is a pressure sensitive rupture panel that is accurate, dependable and provides rapid response venting in the event of deflagration. Features and options of an OE explosion panel include:

Leak-tight seal
Standard & special sizes
Minimal or zero fragmentation
Flat or crowned design
Broad range or materials available
Welded or bolted frames
Square, rectangle, round and custom shapes available
Insulated panels for elevated temperatures
Rapid opening
Maximum vent area
Cycling or static service
Test certifications
Emergency service
Complete in-house manufacturing

OsecoElfab’s explosion protection engineers are experts in using the industry standards and equations to consider all necessary variables when sizing an explosion panel for your applications.