The Tisch Ambient Eight-Stage Cascade Impactor is an aluminium alloy mechanical inertial separator designed to aerodynamically separate ambient particulate into multi fractions in the range of 10μm AED (Aerodynamic Equivalent Diameter) to filtration collection of sub-micron particles 0 to 0.43μm. Use of a Pre-Impactor Size Selective Inlet (High-Capacity Pre-Separator) is used when applications with larger than 9.0μm AED particles are present. The Pre- Separator is designed to remove large particles, which due to inertial energy can cause particle-bounce inside a classical Cascade Impactor and be measured incorrectly. The Pre-Separator is a large capacity, single-jet impactor where the total suspended particulate air sample is drawn in through a single inlet nozzle, accelerated, and only particles <9.0μm AED exit to be further aerodynamically separated in the Cascade Impactor Stages.
The Tisch Model 20-800 series of Cascade Impactors are designed for applications in ambient air where Non-Viable (Non-Biological) aerosol is to be collected and measured for its concentration by aerodynamic particle size. The concentration of particulate is calculated by pre and post weighing of the 81mm sample substrates located below each Orifice Stage. As particles pass through each successively smaller diameter orifice stage the sample rate is accelerated. As the aerosol exits each orifice it will curve around the impaction sample substrate. Particles which have an aerodynamic diameter and inertia that can not stay in the sample air stream break free from the flow and collect by impaction onto the sample substrate. By subsequently making the orifice diameter smaller on each Stage of the Cascade Impactor, the particles are increased in velocity and the aerodynamic separation of particles over a large range can be determined.
The first commercial Cascade Impactor was introduced in 1945 in the United Kingdom by Dr. K.R. May Ph.D. and design and data published in the Journal of Scientific Instruments #22. The design uses a single orifice jet impacting onto a glass microscope slide and four successive Stages with decreasing orifice diameters. The “May Impactor” remains a valuable laboratory tool even today with a well characterized and precise particle separation efficiency. Its only limitation is the sample flow rate is low and the glass slides require grease-coatings to collect the sample for analysis. The Tisch Ambient Eight-Stage Cascade Impactor concept was designed and published by Dr. Aerial Andersen in Provo, Utah in 1958 (Journal of Bacteriology #76). In an attempt to improve collection efficiency Dr. Andersen developed the multiple Stage, multiple-Orifice Cascade Impactor. The unique design of multiple orifice jets in one stage allowed for higher sampler flow rates and a larger sample substrate to collect greater mass concentration for weighing accuracy and later chemical speciation analysis. The design has been utilised by many researchers in the Environmental, Industrial Hygiene and TE-20-800 Pharmaceutical industries for thirty years and has been extensively tested and verified for characterisation. Several commercial copies of the original design are being fabricated in world today.
The Tisch Ambient Eight-Stage Cascade Impactor is machined from aircraft alloy aluminium to a high precision of tolerances. The physical design and attention to tolerances of design and orifice hole diameters insures the reproducibility of accurate size selective data. However, to ensure that these machine tolerances are maintained each and every orifice on each successive stage is verified using both a manual machine-pin-gauge test as well as an optical comparator.
For special applications where verification and actual physical calibration using liquid and solid NIST traceable aerosol standards is needed, contact us for availability and calibration procedure.
SPECIFICATIONS
Impactor: Size: 7.75” Height x 4.25” Diameter
Weight: 3.95 lbs.
System Components:
One (1) Alloy Aluminium Inlet Cone
Eight (8) Alloy Aluminium Orifice Stages Numbered ( 0 to 7 )
One (1) Alloy Aluminium Filter Stage Numbered ( F )
One (1) Alloy Aluminium Base Plate with Three (3) Hold-Down Springs
Nine (9) Stainless Steel Sample Substrate Collection Plates ( 81mm Diameter )
Vacuum Tubing
Operation Manual
Carrying Case
Options:
Size-Selective Inlet (High-Capacity Pre-Separator)
81mm Glass Micro-Fiber Sample Substrates Open Centre for Stages 0 and 1
81mm Glass Micro-Fiber Sample Substrates for Stages 2, 3, 4, 5, 6, 7 and F
Model PM 700 IP/C Pharmaceutical Inlet Induction Port ( Special Inlet Induction prior to Size Selective
Inlet (High-Capacity Pre-Separator) for Metered and Powder Dose Inhaler Testing.
Vacuum Pump:
ALPM Design Sample Rate
115 VAC 60 Hz
220VAC 50 Hz
12 VDC
Sample Flow Rate:28.3 ALPM at ± 1.5 ALPM
Differential Pressure: 13.6” Water at 28.3 ALPM Sample Rate and Glass Fiber Substrates/Filter
Ordering Information:
TE-20-800 Ambient (Non-Viable) Eight-Stage Cascade Impactor
Parts and Consumables
TE-10-727 Field Calibrator
TE-20-301 81mm Glass Fibre Substrate Discs (100 per box)
TE-20-301QZ 81mm Quartz Fibre Substrate Disc with Open Centres, for Stages “0” and “1” (50 per box)
TE-20-305 81mm Glass Fibre Substrate Discs with Open Centres, for Stages “0” and “1” (100 per box)
TE-20-305QZ 81mm Quartz Fibre Substrate Disc with Open Centres, for Stages “0” and “1” (50 per box)
TE-20-704 Set of 11 Silicone O-Rings for Stages “0” to “F”
te-20-800-spec-sheet-2008