Isokinetic Coupler and Sampling Probe for the 3330 Optical
Contents
1. ISOKINE TIC COUPLER AND SAMPLING PROBE FOR THE 3330 OPTICAL PARTICLE SIZER SPECTROMETER E USER S GUIDE Description Isokinetic Sampling To achieve a representative sample of a particle size distribution sampled from a test duct it is necessary to sample isokinetically An isokinetic sample requires that the gas velocity going into a probe matches the velocity going around the probe Failure to match velocities will cause a sizing distortion The distortion favors large particles if the probe velocity is lower than the duct velocity and favors small particles if the probe velocity is higher than the duct velocity Equal velocities can be achieved by making the ratios of the flows to the cross sectional areas equal for the probe and the duct Probe Flow Duct Flow OC eee ean T E T E Probe Cross Sectional Area Duct Cross Sectional Area Isokinetic Sampling Probe The sampling probe is designed to provide an isokinetic flow when the probe is sampling from the test duct such as what is used for the ASHRAE standard 52 2 An ASHRAE 52 2 duct is 2 x 2 610 x 610 mm in cross section and the typical flow rate is 2000 cubic feet per minute cfm or 3400 m h Sampling Probe ae is designed to be an isokinetic sampler at that flow rate 500 feet Isokinetic per minute or 2 54 m s face velocity Nozzle Isokinetic Sampling Probe Isokinetic Coupler The Isokinetic Coupler is an interface that provides a second isoki2. el 49 241 523030 P N 6005419 Rev B 2013 TSI Incorporated Printed in U S A
3. into the instrument without first having the pump running the optics chamber is at risk of becoming contaminated and or the unit may not be able to start the measurement because of high background scattering light When the OPS is connected to a test duct TSI recommends that Keep Pump On mode be enabled In Keep Pump On mode the OPS pump is always running any time the unit is turned ON Further details regarding Keep Pump On mode can be found in the OPS user manual under Setup System Flow Calibration When sampling from a test duct it is also recommended that you connect the OPS exhaust back into the test duct downstream of the sample probe This will ensure that the inlet and outlet pressures on the OPS are the same and the OPS sample and sheath flows are maintained at the desired flow rates Parts List lsokinetic Coupler and Sampling Probe assembly P N 1130011 includes e Sampling Probe with isokinetic sampling probe tip e lsokinetic Coupling containing critical orifice to set auxiliary flow e Absolute filter to protect orifice e Tubing Accessories Needed e External pump to maintain main flow through coupler e g TSI model 3032 TSE UNDERSTANDING ACCELERATED TSI Incorporated Visit our website www tsi com for more information USA Tel 1 800 874 2811 India Tel 91 80 67877200 UK Tel 44 149 4 459200 China Tel 86 10 8251 6588 France Tel 33 491 11 87 64 Singapore Tel 65 6595 6388 Germany T
4. netic sample between the sampling probe and the inlet to the 3330 OPS A flexible plastic tube containing Inner Nozzle a Critical orifice protected by a filter and an external pump 4A m not supplied are used to pull an auxiliary flow of 6 L min l through the isokinetic coupler The flow into the inner a a L 7 nozzle is the 1 L min sample flow of the OPS The coupler P 4 Critical is designed so that the 1 L min is sampled isokinetically H Filter Orifice from the main flow The total flow into the coupler is then 7 L min cfm ca Isokinetic Coupler Operation 1 Install the Isokinetic Sampling Probe into the filter test duct and secure The probe tip must be parallel to the test duct to prevent sizing distortion 2 Connect the lsokinetic Coupler to the bottom of the sampling probe 3 The 3330 OPS can be connected with a piece of conductive tubing such as TSI part number 3001788 conductive tubing 3 foot length included 4 Connect an external pump e g TSI model 3032 to the end of the tubing from the isokinetic coupler that contains the critical orifice 5 Switch on the external pump Probe and Coupler Connected to OPS When you are attaching the inlet of the OPS to a test duct you should have the OPS pump turned on before connecting the OPS to the duct This is best accomplished by using the Keep Pump On mode of the OPS see Note below If particles are introduced
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