Anti-Deflagration
Central Vacuums

The fire triangle represents the three conditions necessary to produce fire. It takes combustible materials (such as wood, certain metals or chemicals); fuel (oxygen) and heat. A fire cannot take place without one of these three elements. And since the presence of combustible materials are often unavoidable given the nature of a company's business, it presents a fire hazard when there are sources of ignition. Hence the importance of having facilities that meet NFPA (National Fire Protection Association) standards.

Fire prevention must occur as early as possible. For example, instead of installing a foolproof collecting system in an area at risk, the question should be asked whether a regular (more affordable) system can be installed in an adjacent room where the risk of fire is significantly lower.

In summary, in order to prevent the risk of fire in the workplace, you must eliminate potential causes of fire, put in place prevention and intervention plan, then raise awareness and train the staff.

Here are the 7 main sources of ignition to watch out for and some precautions to avoid them and thus comply with NFPA standards:

1. Heated work (e.g. welding): provide a clearance zone or partitions.
2. Open flames and smouldering fires: add detection devices (prevention) and emergency ventilation (reaction).
3. Electrostatic discharges: use conductive materials with a grounding (GR).
4. Friction, mechanical sparks and hot particles: maintenance routine and scrupulous monitoring.
5. Hot surfaces: thermal insulation, temperature detection probe.
6. Spontaneous chemical reactions: prevention by chemical compatibility analysis, heat and gas detectors, continuous aeration.
7. Electrical equipment: provide regular maintenance, classify hazardous locations and replace non-compliant electrical equipment and devices.

To make a fire, three things were needed: combustible material, fuel and a heat source. Add to that a cloud of concentrated combustible particles and you get a deflagration. Now add containment to these four elements and you have an explosion. The reason is simple: each particle is surrounded by oxygen (oxidizer), so the finer the particles, the easier the combustion takes place.

In business, the different types of combustible particles are grouped into 5 categories:

• Food: cocoa, spices, flour and cereals, corn, sugar, etc.
• Metals: aluminum, copper, tin, iron, magnesium, titanium, etc.
• Chemical compounds: acetylsalicylic acid, benzoic acid, fumaric acid, mannitol, sulfur, etc.
• Plastics: ABS, rubber, nylon, polycarbonate, polyethylene, polypropylene, resins (epoxy), etc.
• Other products: wood or cardboard dust, cellulose, charcoal, cotton, etc.

However, not all particles can lead to a deflagration or explosion. Here are some examples of non-combustible particles:
welding fumes, combustion gases, alumina, silica, clay, salts and minerals, baking soda, fluorine, etc.

Aside from compliant installations, the biggest challenge for businesses is cleaning. A clean environment will eliminate the danger of a second deflagration.

Here is a summary of recommendations from BBA, a Canadian consulting engineering firm specialized in the application of NFPA regulations.

Each company must ensure that an analysis of the hazards associated with combustible dust, called Dust Hazard Analysis (DHA), is completed.
The two main objectives are:

1. Assess the dangers of fire, deflagration and explosion under normal and abnormal conditions.
2. Provide recommendations to manage these hazards.

The analysis of the hazards associated with combustible dust is carried out in four stages:

1. Prior risk assessment (equipment / buildings)
2. Identify and implement temporary solutions (mitigation measures) to protect the workers and their work environment while ensuring the continuity of operations (production).
3. Finalize the risk analysis (DHA)
4. Implementation of permanent control solutions and a management system

Ultimately, the objectives are to prevent explosions, prevent a second deflagration, protect in the event of an explosion and prevent the spread of flames and pressure waves.

Drainvac has acquired a great deal of experience in the commercial and industrial environment for almost 40 years now. Our expertise has led us to support several companies in achieving their objectives in terms of fire prevention and protection (and explosion) in order to comply with NFPA standards, mainly through two approaches:

1. Cleaning dust accumulations, powders and other residues.
2. Vacuum at the source

These two methods should be advocated to prevent second deflagration. The accumulation of dust on surfaces or inside equipment can represent a significant danger. A single explosion can do a lot of damage, but if the blast of it lifts the accumulated dust and causes a second deflagration, it leaves no chance.

Drainvac has therefore developed commercial and industrial vacuum cleaners specially designed to safely collect this type of accumulated dust. Installed in such a way to comply with NFPA standards, the dust is routed via a grounded network (GR) and then collected in a separator (SEPA.INOX02). What is not intercepted then goes into a second separator, made of plastic, which mixes the collected dust with water (when the vacuumed chemical compound can be mixed with water without danger naturally). In the case of metallic dust such as magnesium for example, we have other specialized equipment where everything is done dry.

Vacuuming at the source has the advantage of avoiding any dust accumulation at all times and can play an important role in the prevention of a main explosion. Drainvac is also specialized in custom-made tools and systems to meet specific needs. Do not hesitate to contact us!

Whether cleaning is done at the source or not, know that it is also important to regularly clean your vacuum system's pipelines. It is also another type of automated installation that we offer: www.drainvac.com/automatic-pipe-cleaning-systems

No matter what stage you are at in your thinking, don't hesitate to call us for any questions about the safety of your facilities!