Inhalation Exposure System
Full Body Exposure System, The Inhalation Exposure System provides reproducible animal exposure to droplet-borne contaminants and infectious agents. It also produces deep-lung infections that more closely simulate real-world circumstances.The system allows you to vary the concentration of airborne pathogens, the rate of air flow, and the length of exposure, so experiments can be reproduced accurately and adjusted easily. UV lamps and an air incinerator for decontamination provide additional protection in the lab.
The system is a whole-body exposure chamber for the quantitative experimental infection of animals by inhalation of air bearing the pathogenic agent. The heart of the system is the nebulizer-venturi unit into which the suspension is introduced. Air under pressure atomizes the suspension, which is mixed with filtered room air drawn into the system by a suction beyond the decontamination system. By varying the number of micro-organisms in the suspension, the proportion of bacteria-bearing nuclei can be varied. The system permits control of the volume of air moving through the chamber per unit time.
The animals are placed in a compartmented mesh basket within the chamber. Compressed air and vacuum pumps, along with the necessary controls and flow indicators, are built into the system. A programmable control is used to time the preheat, nebulizing, cloud decay, and decontamination periods. A filter and ultraviolet lamps are provided for cleaning the system.
The control regulates the operating cycle of the Inhalation Exposure System, which consists of four periods with preset times:
- Preheat: 15 Minutes
- Nebulizing: 30 Minutes
- Cloud Decay: 30 Minutes
- Decontamination: 15 Minutes
If these times are not suitable for your application, you may easily enter alternate times by using the keypad. The Inhalation Exposure System provides whole-body exposure for 100 mice, 15-20 quinea pigs, or five rabbits.
Improved filtering and ultraviolet lamps aid in the decontamination of the system, and for additional safety, the system operates under negative pressure. The system is equipped with an Allen Bradley programmable control. This sophisticated control is highly functional, very easy to use, and increases the efficiency of the system. The control's visual display screen allows you to read what process is taking place.
- Chamber - An anodized aluminum tank, 22-3/4' in diameter by 22' deep, with a volume of 5 cu. ft., constitutes the infection chamber.
- Basket - A stainless steel, wire mesh basket, 22' in diameter by 14' deep, is provided. The opening in the basket lid can be rotated to each of 5 equal compartments. Each compartment can hold 20 mice, 3-4 guinea pigs, or one rabbit; for a total of 100 mice, 15-20 guinea pigs, or 5 rabbits.
- Lid - A clear acrylic lid, impervious to ultraviolet rays, supports the UV lamps and sample port. Four latches provide pressure on the tank gasket to seal the lid to the chamber.
- Cabinet - The apparatus is housed in a sturdy stainless steel cabinet, mounted on casters. Flowmeters, controls, and nebulizer are mounted on a recessed panel. Cabinet size is 30' wide by 33' deep by 33' high. Weight is about 170 pounds. The incinerator is at the right rear corner of the cabinet. Depending on position, it adds 11' to either the depth or the width. A minimum space of 6' is recommended between the incinerator and adjacent walls or other equipment.
- Filter - The exhausted air passes through an HEPA filter unit with a glass fiber medium that has a minimum efficiency of 99.;97% on particles as small as .3 micron. Filters are individually DOP tested at a flow rate of 100 CFM at 1.2'w.g.
- Controls - Allen Bradley programmable control regulates the four cycles of the Inhalation Exposure System (preheat, nebulizing, cloud decay, decontamination) and increases its efficiency. Displays time in seconds.
- Flowmeters - Two durable and easy-to-read flowmeters accurately measure the airflow to the chamber. The compressed air line flowmeter has a range of 2 to 20 SCFM, and the main air flowmeter has a range of 10 to 100 SCFM.
- Nebulizer - An all-glass nebulizer-venturi unit with septum is provided for atomizing the suspension under pressure and combining it with the air drawn in from the room to provide the proper mixture to be delivered to the chamber.
- Pumps - The system features a very quiet and reliable vacuum pump to provide adjustable flows through the tank of up to 1.67 CFM.
The system is supplied with an air incinerator on the outlet.
A typical application for the Inhalation Exposure System
In a typical experiment for tuberculosis research, the basket is filled with mice, placed in the tank, and the lid is secured to the chamber. Tubercule bacilli are suspended in a solution of 0.1% bovine albumin fraction V and 0.1% Tween-80 and placed in the nebulizer-venturi unit. The air pressure and vacuum controls are adjusted for proper flow: approximately 5 liter/min. for the compressed air and 28 liters/min. (1 cfm) for the main air flow.
The droplets are dried to droplet nuclei before reaching the infection chamber and form an ambient cloud. This cloud is allowed to build up for approximately 30 minutes and then to decay for 30 minutes with the nebulization stopped. The size of the droplet is approximately 2 to 5 microns. The bacilli are deposited in the alveolar spaces and cause lesions on the surface of the lungs.
The cloud is uniform throughout the chamber since animals of the same size develop approximately the same number of lesions. The infection is quantitative, depending on the number of infecting organisms in the nebulizer fluid and the minute breathing volume of the animal.
Before opening the chamber, decontamination of the fur and chamber is accomplished by air washing for 15 minutes with the ultraviolet lamps on.