With the optional Automatic Cartridge Collection Unit added to the Thermo Scientific TEOM Series 1400a Monitor, users gain the ability to sample ambient particulate matter and gases conditionally for later analysis with a choice of collection hardware. Its eight internal flow channels can be fitted with 47 mm filter holders, filter packs, PUF (polyurethane foam) samplers or other sampling devices. Quick-connect fittings provide for the easy exchange of collection hardware
Using the software resident in the Series 1400a Monitor, the user specifies the conditions under which each of the ACCU System's eight flow channels is activated. The flow through the system can be governed by such factors as the real-time mass concentration, time of day, day of week, or analog inputs such as wind speed or direction generated by other devices. Every 10 seconds the Series 1400a Monitor determines which of the ACCU System's eight channels should be active based upon user-defined sampling criteria. Only one channel is active at once, and an internal bypass is opened if none of the eight sampling channels is currently turned on.
The ACCU System utilizes the bypass flow of Series 1400a Monitors equipped with a 16.7 l/min sample inlet and flow splitter. This bypass flow is directed to the hardware through tubing from the flow splitter, and then onward to the auxiliary flow controller in the control unit of the Series 1400a monitor. Inside the ACCU System, a bank of solenoid valves redirects the bypass flow through one of eight sampling devices mounted within the unit, depending upon user-defined sampling conditions.
With an optional PM-2.5 ACCU Inlet, users can sample PM-10 on a continuous basis with the Series 1400a Monitor while using the conditional sampling capabilities of the ACCU System to collect PM-2.5. The PM-2.5 inlet for the ACCU System provides a theoretically-derived cutpoint of 2.5 microns diameter for the bypass air flow entering the ACCU System from the Series 1400a Monitor. The hardware fits directly over the point at which the bypass flow enters the ACCU System.
The standard 47mm filter holders available for use with the ACCU System are suitable for gravimetric analysis, as well as speciation techniques that involve digestion of a sample from a filter. these include analytival chemistry techniques such as AA (atomic absorption) and ICP (inductively coupled plasma).
Other analytical methods for the speciation of particulate matter may require a homogeneous distribution of sampled particles across the surface of a collection filter. In such cases, Thermo recommends the use of the ACCU Filter Holder for XRF. This device uses the same quick-connect fittings as the standard ACCU filter holders. It incorporates the same exchangeable filter cassettes for 47mm diameter filters as Thermo's Partisol family of air samplers.
The ACCU System has been a popular option for particulate sampling under a variety of user-defined conditions, including wind speed and direction, time of day, and analog inputs from external devices. A special sampling mode also enables sample collection on filters by individual, user-defined episode.
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