Venturi Dry Powder Dispenser
The Venturi style dry-powder generator has air entering into one end of the venturi. The powder is fed into the narrowed throat of the venturi by the pressure differential. A funnel that is attached to the body of the venturi holds the powder supply. Then, shear flow disperses the powder into an aerosol in the expansion section. The total flow and the feed flow are functions of the compressed air pressure. The flow rate downstream of the Venturi tube is measured using a dry test meter.
A paper, “A Venturi Disperser as a Dry Powder Generator for Inhalation Studies”, by Y.S. Cheng, E.B. Barr and H.C. Yeh describes the design and operation based on the Venturi principle.
The table shows the stability of Aerosol Concentrations during a 1 month study.
Slide Action Powder Generator
This Dry Powder Aerosol Generator is a pneumatic driven device that can be operated in continuous or single puff configurations. A slide bar is actuated into fill, load and dispersion positions. The volumetric airflows and pressures are set with a Puff Control System. Operational parameters are selectable and are controlled and monitored through a LabVIEW™ operating platform. Dispersion air is discharged with an EXAIR static neutralizer. Puff volumes are determined using a calibrated 0.318”cm diameter differential pressure orifice meter. Intertracheal pressure is measured using a SETRA model 254 pressure transducer. An automated safety overpressure “kick-out loop” is built into the system.
Dry Powder Aerosol Generators
Pneumatic Powder dispersion techniques using airstream, fluidized beds and fluid energy jet mills have been used as dry powder aerosol generators in inhalation studies and for calibration of aerosol instruments. Most powder dispersers have certain limitations on test materials and maximum/minimum aerosol concentrations that can be achieved. The Wright Dust Feeder is good for test materials that form a stable cake under compression, and the fluidized bed generator is useful for free-flowing materials, but neither is suitable for use with sticky powders. For nose-only inhalation exposure systems, generators that can operate at low flow rates, ranging from 10 to 60 L/min. are needed. The Wright dust feeder and the fluidized bed generators can be operated at the required flow rates for certain powders, but are difficult to operate with sticky powders such as TiO2. The following two powder generators were developed for use with the sticky powders.
Constant Flow Aerosol Nebulizer
The Constant Flow Nebulizer is designed to act as an aerosol source capable of operating for a period of 8.5 hours without refilling. It has been particularly useful to produce low concentration aerosols from suspensions or solutions for use in Nose-Only Plenums and Whole Body animal exposure chambers in toxicity studies. At 25 psig the Constant Flow Nebulizer generates 0.588 ml per minute and uses 6.5 liters per minute of air. The nebulization rate is 74µl per liter of air. The aerosol is constantly recirculated in the nebulizer by use of a peristaltic pump.
Lovelace Aerosol Nebulizer
This compressed air Nebulizer system may be used as an aerosol source for a variety of testing and research purposes. It is found in widespread laboratory uses for aerosolizing liquid solutions and suspensions. Water and other fluids have been used as solvents or suspension media. The nebulizer is one of the most efficient nebulizers commercially available.
The nebulizer operating characteristics are described in the table below. The nebulizer is fabricated from a clear acrylic (cup) and a tooling compound (top). The jet is acrylic, however, it is also available in Delrin, Brass or Stainless Steel. The nebulizer is sealed between the cup and top with a neoprene O-ring.
A Nebulizer Control Unit is also available.
P.O. Box 2070, Moriarty, NM 87035 us
High Output Aerosol Nebulizer
The High Output Aerosol Nebulizer is designed to fulfill the need for an aerosol source operating with several cubic feet per minute of compressed air. Most often used in conjunction with large whole body inhalation exposure chambers, it is also ideal for generating test aerosols to characterize high volume sampling systems.
Body and baffle are lucite, jet is brass and exit system is stainless steel.
Nebulizer operating conditions are listed below.
Slit Jet Aerosol Nebulizer
The In-Tox Slit-Jet Aerosol Nebulizer is a constant feed Nebulizer. The liquid is pumped, via a peristaltic pump through an adjustable discharge rod and over a second rod which discharges compressed air through a small slit jet. As the liquid flows over the air jet it is nebulized. The aerosolized agent then exits via the top of the Nebulizer. The liquid dispensing rod can be adjusted to maximize nebulization. Input air pressure is normally maintained between 25 and 30 psi, but can be increased at the users discretion. See chart below…
Recent advances in pharmaceutical powder technologies and scientific interests in bio aerosols have predicated the necessity of efficient laboratory scale aerosol generation devices for research purposes. The slide action powder generator (SAPG) was designed to deliver precise, known qualities of test article directly into the lung with a single breath. The SAPG was tested with bulk pharmaceutical, medicinal vehicle and bacterial powders to determine their mass transfer, mass transfer efficiency and particle size distribution (PSD).
· Different Dry Powders are generated with different efficiencies by the use of the SAPG.
· Particle charging during dispersion causes agglomeration resulting in larger aerosol particle sizes than bulk compound.
· As a result, each material generated with the SAPG must be characterized for size distribution and output efficiency.
Available in a one and two station model.
Fluidized Bed Aerosol Generator
The Fluidized Bed Aerosol Generator (FBAG) has been a useful method of generating aerosols from powders or dusts. Observations of particle deposition patterns in inhalation exposure systems with and without a Kr aerosol discharge device suggested that the aerosolized particles may carry a large number of electrostatic charges. Measurements of average charge carried by aerosols generated from an FBAG were performed for a variety of aerosolized materials. It was found that average charge per particle was higher for insulators than for metals and increased with increasing fluidization airflow for most materials. Also, the charge level was found to be changed with the length of operating time.
Dusts and powders are among the common sources of air pollutants in workplace environments. To study potential health hazards from inhaling these pollutants, an aerosol generation system for dispersing these dusts or powders is required. The fluidized bed aerosol generator (FBAG) uses a flow of air through a bed of powder to aerosolize fine particles. In this process, the particles are vigorously agitated in the FBAG prior to release into the mainstream. During this process, contact charging mechanisms between aerosolized material and bed material or bed housing wall will act to place electrostatic charges on the aerosolized efficiency in the respiratory tracts when inhaled.Therefore, it is important to know the charge level carried by aerosols for inhalation experiments.
In-Tox Products has two sizes of the FBAG available. A 1” and a 2” model FBAG are the standard sizes kept in stock. These models are available in Brass or Stainless Steel. The FBAG comes mounted on a base with a cabinet that contains the controls for the system.Type your paragraph here.
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