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Operation Manual HORIBA APDA-371
Particulate Monitor
Date:
April, 2010
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HORIBA Europe GmbH, Julius-Kronenberg-Str. 9, D-42799 Leichlingen, Telefon: +49(0)2175-8978-0, Fax: +49(0)2175-8978-50
Page 27
5
FLOW SYSTEM and FLOW CALIBRATIONS
5.1
Flow System Diagram
The APDA-371 airflow control system is very simple and effective, consisting of a few rugged components. Proper
operation of the flow system is critical if accurate concentration data is to be obtained from the unit. The key aspects of
proper flow system maintenance are Leak Checks, Flow Checks, and Nozzle Cleaning. These processes are
described in this section. HORIBA recommends performing a leak check and nozzle cleaning before flow calibrations,
as a leak can affect the flow. Flow calibrations require a reference flow meter and a reference standard for ambient
temperature and barometric pressure. NIST traceable standards are required in many applications. HORIBA suggests
the BGI DeltaCal
brand (available from HORIBA as the BX-307 option). It includes flow, temperature and pressure
standards in one unit.
APDA-371 Flow System
5.2
Flow Type Descriptions
The APDA-371 is designed to operate with an airflow rate of 16.7 liters per minute (lpm). This is important, because the
particle separators (PM
10
inlets, cyclones, and WINS impactors) require this flow rate in order to properly separate the
correct sizes of particles from the air stream. All of these separators use the inertia of the particles as they flow through
the inlet to sort out the ones above a certain size (cut point) so that they won’t be measured by the instrument. If the
airflow rate is not maintained within ±5% of the design value flow rate of 16.67 lpm, then particles of the wrong size may
be allowed through or sorted out. Periodic APDA-371 airflow calibrations must be performed to ensure the unit
Mass Flow
Sensor
Automatic Flow
Controller
Barometric
Pressure
Sensor
Filter Temp and
RH sensors
Debris
Filter
Inlet
Receiver
Outlet
Beta
Block
Manual Flow Valve
(old APDA units
BX-592
Temperature
Sensor
Vacuum Port
to pump