E-Beam Water Mist for Fire Fighting--Possible Halon Replacement
Source: UFTO
Date: 3/17/97    Record No.: 10430
Contact: Contact: Dr. Arnold. J. Kelly, Chief Engineer.
Charged Injection Corporation, Monmouth Junction, NJ
(908) 274-1470, fax (908) 274-1454, spraytron@aol.com

E-Beam Water Mist for Fire Fighting--Possible Halon Replacement
Misting sprays have been shown to be particularly effective in quenching fires. Considerably less water is required to put out a fire when it is in mist form as opposed to the larger droplet sprays generated by typical sprinkler nozzles. While effective in suppressing fires with little water damage, mist nozzles suffer from an inability to convey droplets to cloistered areas where all to often fires can take hold. This failing is shared by all uncharged sprays, whose droplets follow ballistic or aerodynamically influenced trajectories.

This is not true of charged sprays. Charged droplet trajectories are controlled by mutually induced electrical forces that automatically drive them to grounded surfaces no matter how distant these surfaces are from the nozzle. These forces literally force charged spray droplets to wrap around grounded objects in their path. For instance, charged spray droplets will flow to a fire under a bench that would not be contacted by uncharged droplets. In addition, since flames are grounded and conductive, they are attractive to charged droplet sprays, which will preferentially flow toward them.

Such a technique could potentially provide a replacement for Halon, which is being phased out as a greenhouse gas.

Charged Injection Corporation (CIC) is currently working under Navy sponsorship on the development of an electrostatic nozzle for dispersal of fire fighting water mists. CIC has developed a number of nozzles that are capable of providing high flow rate charged sprays. The Plasma Physics Lab at Princeton is working closely with CIC, providing important modeling and theoretical support.

All of CIC's nozzles involve the same concept, the driving of free charge (electrons) into a passing fluid. Once charged, the fluid predictably atomizes and self-disperses. Non-conductive fluids, such "clean extinguishing agents" of the type produced by 3-M, and fuels and oils, are easily charge-injected by simply immersing an electrode in the fluid upstream of an orifice. These SPRAY TRIODE atomizers are compact, require very low power for operation, and can be operated at arbitrarily high flow rates.

While SPRAY TRIODE devices will short out when used with water, charge injection can be obtained by a second means. CIC is under Navy contract to develop an electrostatic water mist nozzle using an electron gun to drive charge directly into water streams. This patented technology uses a peanut sized electron gun as the source (the SPRAYTRON is similar to what's in a TV picture tube). The electrons pass through a thin window to the exterior.

This technique opens the way to the development of nozzles that are capable of operating at any flow rate of interest. Most importantly, since droplet size is solely a function of the amount of charge imparted to the fluid, the SPRAYTRON source permits direct electronic control of spray droplet size.

Many other applications are also possible with CIC's devices, such as dispersing insecticides or herbicides, spray coating and painting, fuel injection, drug delivery, desalination, and even size separation of microparticles.