V e T i m e C o u n t i n g | Teledyne 651 guide

Particle Counting

Teledyne API Ultrafine Particle Monitor - Model 651

In totalizer mode, the accuracy of the concentration is increased by sampling for a longer period and counting more particles. The concentration is displayed on the front panel in totalizer mode and is calculated by:

	concentration =	total counts	=	n
		volume of aerosol flow in the sensor		Q × t

where

Q = Sample flow rate ration. It is very close to its nominal value of 0.12 L/min.

t = sample time in sec.

L i v e - T i m e C o u n t i n g

Coincidence occurs when more than one particle occupies the optical sensing region simultaneously. The optical detector cannot discriminate between the particles and multiple particles are counted as a single particle. At higher particle concentrations, particle coincidence begins to have a significant impact on the measured concentration.

The Model 651 corrects for coincidence continuously with the instrument electronics performing a “live-time” correction.

Live-time refers to the time between electrical pulses. This is the total measurement time interval minus the time during which the counter is disabled with one or multiple particles in the optical sensing volume (the dead time). The dead time should not be included in the sample time since only the particles already in the viewing column can be counted. The actual particle concentration therefore equals the number of counted particles divided by the live-time (actual sample time) and the aerosol flow rate.

To measure live-time, a high-speed clock and accumulator are used. The accumulator adds up the live time and the counter adds up pulse counts. The particle concentration is then calculated by

Ca	= number of counted particles	×	1
	accumulate d live - time		aerosol flow rate

Note: At concentrations > 106 particles/cm3, the status reads Over Range. If this occurs, the Model 651 is outside of the concentration operating range and the number of particles shown on the display could be lower than the actual concentration.

62	07506C DCN6727

Image 64

Teledyne 651 operation manual V e T i m e C o u n t i n g, Concentration = Total counts

Contents

Model Page Trademarks This page intentionally left blank F e t y M e s s a g e s Laser Safety R N I N G R r a n t y This page intentionally left blank O u t T h i s M a n u a l V i s i o n H i s t o r y Viii Contents Particle Counting Maintenance, Service, and Troubleshooting G u r e s SFC Set Flow Rate Calibration Constant B l e s Table A-1 Xiv R p o s e How This Manual is OrganizedG a n i z a t i o n L a t e d P r o d u c t L i t e r a t u r e T t i n g H e l p O d u c t D e s c r i p t i o n Product OverviewA P T E R Specification s Parameter Specification Parameter Water System Physical Features W i t W o r k s 2illustrates the flow system of the Model Model 651 Flow System Schematic Unpacking and Setting Up the Model C k i n g L i s t Model 651 Maintenance Kit PN DU0000169 P a c k i n g Installation Connecting the Water SupplyEquipment Remove Protective Caps Bracket Screw Connecting the Water Supply Connecting the Water Exhaust Tube Connecting the Aerosol Supply Connecting the Aerosol Supply Nozzle Securing Inlet Screen Assembly in Place Installing the Model 651 in a Rack Connecting the USB Cable Connecting Power and Warming up the Model Warm-up Screen Moving the Model 651 Short Distances Moving and Shipping ModelPreparing the Model 651 for Shipping and Storage 07506C DCN6727 O n t P a n e l Instrument DescriptionDisplay Indicator Light Status Messages C k P a n e l Optics Module T e r n a l I n s t r u m e n t C o m p o n e n t sVacuum Supply Water System FansCircuit Boards Internal Clock Data Communication Ports RS-232 Serial Connections Ethernet Communication Port 07506C DCN6727 Outdoor Operation Procedures Instrument OperationE r a t i n g P r e c a u t i o n s C o m m e n d e d O p e r a t i o n P r o c e d u r e s Standard Operation Procedures ∙ Status ∙ Setup ∙ Total R m u pS p l a y / U s e r S e t t i n g s Home Screen Status Description Setup Screens Warmup On AfterOFF SET Time Address Total Screen Mask 07506C DCN6727 Technical Description E o r y S i g n o f t h e M o d e l 6 5 Sensor Pulse Height Flow System Critical Flow Temperature Control Inlet Pressure Measurement Water Removal System Page 07506C DCN6727 Particle Counting T a l C o u n t a c c u r a c y V e T i m e C o u n t i n g Concentration = Total counts N c e n t r a t i o n M e a s u r e m e n t Concentration = N × t 07506C DCN6727 T a l i z e r M o d e 07506C DCN6727 M p u t e r I n t e r f a c e Computer Interface Commands, and Data CollectionEthernet Programs and Features Choose Turn Windows features on or off Flash Drives Flash Memory Data Files Line Example of data record USB RS-232 Serial Communications Terminal Communications Communications Parameters Read M m a n d sSET 07506C DCN6727 07506C DCN6727 Maintenance, Service Troubleshooting U t i o n M o v i n g t h e C o v e r P l a c e m e n t P a r t s K i t s M o v i n g a n d Install i n g t h e W i c k T e A n g i n g t h e F i l t e r s R o s o l F l o w C h e c k s Model 651 Flow Schematic E a n i n g t h e W a t e r B o t t l e S p e c t i n g a n d C l e a n i n g t h e F a n s E a n / R e p l a c e t h e O r i f i c e s S p e c t L i q u i d L i n e s A t u s M e s s a g e s Troubleshooting Troubleshooting INLET/DRAIN C h n i c a l a s s i s t a n c e T u r n i n g t h e M o d e l 6 5 1 f o r S e r v i c e Primer on Electro Static Discharge W S t a t i c C h a r g e s a r e C r e a t e d Static Generation Voltages for Typical Activities Sensitivity of Electronic Devices to Damage by ESD M m o n M y t h s a b o u t E S D D a m a g e S i c P r i n c i p l e s o f S t a t i c C o n t r o l General Rules 07506C DCN6727 Working at the Instrument Rack Working at an Anti-ESD Work Bench Opening Shipments from Teledyne API’S Customer Service Transferring Components from Rack to Bench and Back Packing Components for Return to TAPI’s Customer Service 100 07506C DCN6727 Commands Read SET Command Explanation Read Commands RAI Read Analog Input Voltage A D C o m m a n d sRAI Rall Read Operating Condition Rall RD Read Displayed Concentration RCT Read Current TimeRCT RIE Read Instrument Errors RIF Read Aerosol Flow RateRIE RIF RL Read Laser Current RIS Read Instrument StatusRIS RLL Read Liquid Level RPA Read Absolute Pressure TransducerRPN Read Nozzle Pressure Transducer RPV Read Vacuum Pressure RRD Read Data Record RRD RTA Read Cabinet Temperature RTC Read Conditioner TemperatureRRS Read Status Record RRS RTO Read Optics Temperature RTG Read Growth Tube TemperatureRV Read Firmware Version Number SM Set Mode T C o m m a n d s SFC Set Flow Rate Calibration Constant SA Set Auxiliary Flow ValveSFC SP Set Pump Vacuum SR Set Real-time Clock Sstart Starts a New Sample Sstart T a R e p o r t i n g R e c o r d s ST Set Transport Flow CNT RecordPstd Record Status Tinlet Index Aerosol inlet 43, 45 External vacuum source Orifice Teledyne Contact Information Index-5