ignitable / explosible fugitive dust caused by mechanical shredding and handling / baling of shredded paper.
The Piian High Pressure Mist System represents an efficient and effective fire and or dust explosion mitigation tool. A Piian High Pressure Mist System
will increase the moisture content of the air within the envelope of a building and consequently the moisture content of the dust and stored paper
within a paper processing building. Importantly, it will do so without causing undue wetting that leads to problems for the operator which include,
clogging of machinery, saturation of material, damage to material, handling problems, surface water issues, ground water problems etc.
Increasing the moisture content of paper dust particles is an accepted dust mitigation practice that has been documented by the NFPA, OSHA and
AQMD.
When paper dust particles are subjected to a moisture content increase, they increase in mass and so lose their ability to remain fugitive (buoyant) in
the air and to contribute to dust distribution and layering. Secondly, dust particles subjected to moisture increase agglomerate and behave as larger
particles that have an increased ignition temperature, decreased exposable / combustible energy and minimum exposable concentration.
NFPA 654-2006 and NFPA 664-2012 are the standards by which Piian Dust Suppression Systems are designed and applied for the prevention of fires and
or explosions in paper (and wood) processing.
Within NFPA 654-2006, please refer to the following:
Sections A.3.3.4 and A3.3.16 – The Piian High Pressure Mist System will reduce the incidence of combustible dust, moisture content is a factor used in
determining the deflagration hazard of dust. The system will maintain paper dust above its MEC (minimum explosible concentration) and will increase
its MIE (minimum ignition energy).
Section 8.2.1.2 – The system will significantly reduce the incidence of fugitive dust, will slow the buildup of dust layers on horizontal surfaces and will
decrease the housekeeping / cleaning load.
Section 8.2.2.1 – Dust with increased moisture content will less prone to forming dust clouds during cleaning.
Within NFPA 664-2012, please refer to the following sections:
Section 3.3.25 – where the NFPA makes the connection between combustible wood processes and paper processes. (Note: Section 3.3.25 specifically
uses the words “and Paper”).
Section A.3.3.17 – Where Minimum Exposible Concentration (MEC) is defined and where the moisture content of paper dust is a critical outcome
factor.
Section A3.3.27.1 – Moisture content is a factor used in determining the deflagration hazard of dust.
Section A4.2.2 – Moisture content is a factor that has a profound effect on dust deflagration. Moisture in dust particles raises the Minimum Ignition
Temperature (MIT), Minimum ignition energy (MIE), and minimum exposable concentration (MEC) by increasing agglomeration of particles.
Additionally, the EPA AQMD considers a mist system as a suitable dust mitigation measure per Rule 403 and Rule 1137.
The size of the Piian Mist system determines the rate of moisture addition; the suitable moisture addition rate is determined by Psychrometric
Calculation. The system activation / moisture level within the building is maintained by a Humidistat that causes the mist system to cycle on and off
around a target air moisture level (relative humidity of 75%). Through experience we have learned that this target air moisture level results in a 50%
moisture content addition to dust material and a 1 - 2% moisture content increase in stored paper material.
There is no prescriptive standard from the NFPA, OSHA or AQMD that applies to a mist system for this use. However each authority indicates that
raising the moisture content of dust is an effective method of dust mitigation. The Piian Mist system has been proven to be highly effective in raising
the moisture content of dust in a wide variety of industrial applications, including multiple paper shredding operations, for over 20 years.
The Piian Mist system is designed to be a fire hazard mitigation system, not an actual fire suppression or fire extinguishing system. It is however and
effective an efficient method for prevention of hazardous dust conditions for Confidential Document Destruction Operators.