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BGI COLLISON NEBULIZER | |
December 1997
1. Introduction
The Collison Nebulizer was first described in the scientific literature by Collison in 1935, according to May(1). Over the intervening years, it has become the recognized technique for atomizing liquids and suspensions. The original version had 3 jets and BGI is responsible for the standardization and publication of the 6 jet version(2).
Nebulization is taken to mean a refinement of two fluid atomization. In an atomizer, a gas is used to aspirate the liquid into a (usually) sonic velocity gas jet, wherein it is sheared into droplets. In a Nebulizer, this liquid/gas jet is impacted against a barrier (the inside of the jar) to remove the larger fraction of the droplets.
There is one basic type of Collison Nebulizer, known as the modified MRE, which is manufactured by BGI. MRE stands fro Microbiological Research Establishment, located in Porton, England.
All Collison Nebulizers of current BGI manufacture, have all the metal components fabricated from 316 stainless steel. All "O" rings are buna N or silicone rubber. No flat gaskets are currently utilized. Glass jars are either Crown Glass (standard) or Pyrex (precious fluids jar only).
2. Safety Precautions
While the recommended pressure to be applied to the nebulizer may vary from 20 to 100 psig., it must be clearly understood that this pressure is expanded to just above atmospheric, inside the jar. The glass jar is not to be subjected to pressures above 1 psig under any circumstances! Great care must be exercised at all times when connecting the nebulizer's output to other apparatus, to ensure that the flow of gas out of the nebulizer is not restricted in any manner that will cause significant back pressure.
The Collison Nebulizer is intended to be utilized by trained scientific professionals. BGI will bear no responsibility for misuse.
3.0 Set up
3.1 Air. It is the responsibility of the investigator to supply a source of clean, compressed air. The volumetric requirements as follows:
Pressure psig-------------------------------------------Volume
of Free Air in LPM
--------------------------------------------------------3-Jet--------6-Jet
20-------------------------------------------------------6------------12
40------------------------------------------------------10------------20
60-----------------------------------------------------13.5-----------27
80-----------------------------------------------------17.3----------34.5
100-----------------------------------------------------21------------42
It is recommended that a precision pressure gage be fitted to the plugged end of the "T". This may be accomplished by removing the plug screw by hand. A schematic diagram of the basic set up is shown in figure 1. All parts are shown in Figure 2.
3.2 Liquid Level
No specific liquid level is recommended. This is because the "T" may be pulled up or pressed down to a variety of positions. The important point is to begin with the tip of the nozzle immersed no more than 3/8 of an inch below the surface. Deeper immersion will cause the surface of the liquid to interfere with the formation of the jet. For clarification of this point see Figure 3.
3.3 Cleaning
Basic cleaning functions can be performed by disconnecting the apparatus from the air hose and removing and emptying the jar. All components can then be immersed in a cleaning solution appropriate to the material being aerosolized. Ultrasonic cleaning is highly recommended.
The nozzle may be removed from the "T" stem by hand (since 1996). A small, custom made, "O" ring is fitted to the stem, in a groove above the threads, to seal the juncture.
If an internal jet becomes plugged, it may be cleared with the clean out drill (CN-11) supplied with all new units.
4.0 Precious Fluids Jar
This is a fabricated pyrex jar, which has a 5 ml well formed into the bottom. It may be used as a replacement for the standard jar. However, it must be utilized in conjunction with the extension sleeve (CN-41) to the bottom of the nozzle. the purpose of the sleeve is to permit the nozzle to operate in a position sufficiently elevated such that the spray does not interact with the bottom of the jar. Its application is best illustrated by viewing Figure 4. The sleeve is slotted to permit bending the tabs thus formed, inwards for the purpose of achieving a firm fit between the sleeve and the nozzle.
5.0 External Fill Adaptor
The purpose of the external fill adaptor is to permit the addition of liquid while the Collison is running. Replacement liquid can not simply be poured into the jar through a fill hole because there is a slight pressure inside the jar and pouring liquid past he jets may cause unaccountable difficulties with the aerosol production.
The external fill adaptor (CN-42) comprises a luer bulkhead adaptor and cap fitted with a long section of thin tubing. All current production lids have a threaded hole fitted with a plug screw. All current production nozzles have an extra (4th or 7th) hole to guide the thin tube into the nozzle. Each CN-42 is supplied with an "O" ring and lock nut. The application of this device is illustrated in Figure 5.
6.0 Further Information
The best "cookbook" reference of the application of the Collision Nebulizer is and remains the one by May(1). Because of the universal acceptance and use of this device, references in aerosol-related literature are constantly occurring and should be consulted when appropriate or necessary.
7.0 Component Parts List
CN 24 ------JJet (3)
CN 25 ------JJet (6)
CN 27------Bottle
CN 40------Precious Fluids Bottle
CN 39------"O" Ring - Silicone
CN 43------Plug Screw
CN 44------"O" Ring
CN 47------Nut
CN 48------"T" Stem
CN 49------"O" Ring
CN 50------Compression Nut
CN 51------Conical Ferrule - TFE
CN 52------Ferrule, Flat-SS
CN 53------Lid
CN 54------"O" Ring
8.0 Disclaimer
The Collision Nebulizer is subject to all the terms of BGI Incorporated standard limited warranty. The nebulizer is a specialized article of research equipment intended for use by trained professionals. No liability is accepted by BGI Incorporated on account of misuse, misapplication or mishandling. BGI Incorporated specifically does not condone nor endorse any application or use which involves restricting emissions from the device and thus causing pressurizing of the jar. Further, BGI Incorporated accepts no liability for exposure to toxic, infectious or harmful substances resulting from the use of this apparatus.
Limited Warranty
BGI Incorporated warrants equipment of its manufacture and bearing its nameplate to be free from defects in workmanship and material. We make no warranty, express or implied, except as set forth herein.
BGI's liability under this warranty extends for a period of one (1) year from the date of BGI's shipment. It is expressly limited to repairing or replacing at the factory during this period and at BGI's option, any device or part which shall within one year of delivery to the original purchaser, be returned to the factory, transportation pre-paid and which on examination shall in fact be proved defecting. BGI assumes no liability for consequential damages of any kind. The purchaser, by acceptance of this equipment, shall assume all liability for consequences of its misuse by the purchaser, his employees or others. This warranty will be void if the equipment is not handled, installed, or operated in accordance with our instructions. If damage occurs during transportation to the purchaser, BGI must be notified immediately upon arrival of the equipment.
A defective part in the meaning of this warranty shall not, when such part is capable of being repaired or replaced, constitute a reason for considering the complete equipment defective. Acknowledgment and approval must be received from BGI prior to returning parts or equipment for credit.
No representative of ours has authority to change or modify
this warranty in any respect.
References:
Operational features of this device can be reviewed in an interactive slideshow.
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