Inlets, Accessories and Filter Holders

AMBIENT PARTICULATE SIZE SELECTIVE INLETS – EPA Official Design

       SSI2.5 Standard EPA Inlet

BGI is the recognized leader in the production of the “EPA Louvered PM10 Inlet”.
The BGI MODEL # SSI25 is fabricated exactly to US EPA Code of Federal Regulations (CFR) specifications in terms of Dimensions, Alloy, Heat Treatment and Surface Finish. As required by the regulations it is assembled and verified in the BGI ISO 9000:2008 facility. Only BGI produces a water trap from a solid billet of Aluminum with a high quality glass jar sealed with an “O” ring, not cork which tends to leak. Our strict adherence to EPA’s dimensions means that all of the accessories available for this inlet design will fit without question to all ambient particulate samplers and continuous monitors. EPA published a wind tunnel test article verifying a PM₁₀ size specific cut off diameter of 10μm at 16.67 lpm sample rate.¹

Because the EPA Louvered PM10 inlet has been field and laboratory proven for both PM10 particle aspiration and internal impactor cut point of 10 micrometers, EPA made a request to BGI to produce the louvered section of the inlet, minus the PM10 internal impactor. This new BGI inlet design allows Total Suspended Particulate (TSP) aspiration for sampling devices using the EPA 16.67 LPM flow rate. The TSP aspiration performance of this design was the subject of a study involving several wind tunnels and resulted in a test report.²

                BGI Standard TSP Inlet

Specifications:

BGI Cyclones to Adapt the PM10 Inlet to a PM2.5 Size Selective Sampler

When EPA devised the specifications for PM_2.5 they created the concept of a secondary inlet. This allows the PM10 Louvered Inlet to remove the coarse particles followed by a BGI Very Sharp Cut Cyclone (VSCC) to separate the Fine particles ≤ PM2.5. BGI was the only company to develop a PM2.5 size selective device and have it EPA approved since the 1997 regulations went into effect. The BGI VSCC design also allows ambient continuous monitors to operate without cleaning the inlet for periods of 30 days or more. The original EPA design of the Well type impactor (WINS), proved problematical and has been replaced as the Reference & Equivalent Methods for PM2.5. They are described, with supporting reference material on their individual web pages in this site:

Very Sharp Cut Cyclone The EPA Reference Method for Filter Sampling and Equivalent Method for Beta, Light Scattering and Harmonic Continuous monitors. http://www.bgiusa.com/aam/vscc.htm

The BGI Sharp Cut Cyclone was developed in the late 1990's as a world PM_2.5 size selective separator for ambient PM2.5. http://www.bgiusa.com/aam/pm25scc.htm
It is widely used outside the USA since it has many of the same sizeing characteristics as the EPA approved BGI VSCC.

BGI PM1 Ultra-Fine Sharp Cut Cyclone http://www.bgiusa.com/aam/pm1scc.htm

Inlet Sampling Extension Tubes

                                        Extension Tubes

The 12 inch Inlet extension tube was mandated by EPA to avoid potential bluff body effect from the interaction between the louvered inlet and the enclosure or roof of a sampling device. It also assists in raising the inlet portal to the required 2 meters off the ground. A longer 19.5 inch extension is useful with the shorter TSP sampling inlet. BGI also provides special length extension tubes for automated instruments mounted in shelters. These are fabricated to order.

Specifications:

Aluminum Filter Holder

               Aluminum Filter Holder (Closed & Opened)

The filter holder and cassette are the heart of any carefully designed particulate sampling system. BGI is the only US EPA approved vendor who conforms to the strict adherence to EPA specifications. EPA allowed wavers for molded filter cassettes which have proved problematic for sealing and flaking of the plastic.

Specifications:

Filter Media Cassette

The BGI filter cassette halves are machined to exact EPA standards and the filter support screen is micro-etched to specific tolerances of pressure drop. We utilize only genuine DuPont^® Delrin^™ and all parts are cleaned prior to assembly. BGI 47mm filter cassettes will fit all commercial Low Volume PM10 and PM2.5 commercial configurations which adhere to the published EPA standards.

Specifications:

There are various choices available for the transport of 47mm filter cassettes. BGI believes that only the finest all metal cassette transport holder should be utilized for the handling of the filter blank and sample back and forth to the laboratory.

Our two part filter cassette transport holder surrounds the cassette in an air tight metal container and holds it rigidly centered to prevent any contact of the filter with the container.

                 Cassette Transport Carrier

Specifications:

Cassette Opener

A properly manufactured 47mm filter cassette is very tight fitted and difficult to open without a BGI opening device. The BGI cassette opener has grown to be the industry standard for laboratory handling of filters.

                         Cassette Opener

Mini PM Inlet Version of EPA Design

2005 saw the landmark publication of a unique wind tunnel study by the UK Health & Safety Laboratory, Lee Kenny et al
“Aspiration and Sampling Efficiencies of the TSP and Louvered Particulate Matter Inlets”,
Aspiration efficiencies of various inlets were studied using 4 different European wind tunnels. The major scientific contribution was the agreement among 4 different wind tunnel test facilities. This study vindicated EPA work on the full size louvered inlet, spawned the louvered TSP inlet and proved the aspiration performance of, what has become, the BGI one-third scaled Mini PM Inlet for 5 lpm sampling. .
Based upon the EPA 16.67 LPM louvered design, BGI made a one third size louvered PM10 inlet which incorporates the water removal system and a removable impactor size selective jet.
Unlike the EPA embodiment of the design BGI made the impactor jet removable so that a variety of size selective cuts could be utilized:

These impactor jets were designed using the published principals of V. Marple et al. It is an established fact that if the range of Reynolds numbers and the square root of Stokes number recommended by Marple et al³ are utilized, along with other jet parameters, single jet design goals will always be achieved. BGI verified both the aspiration and cut point of the Mini PM Inlet by field comparison where it was collocated with the EPA FRM samplers.

           miniPM Inlet

The BGI Mini PM inlet is designed for a flow rate of 5 lpm and incorporated into a new mini portable PM sampler, the BGI frmOmni sampler. The frmOmni is made to the same demanding US EPA specifications as the full size sampler and provides identical data with a battery operated portable sampler.

Specifications:

Filter Holder with 0.562 Diameter
          to fit Mini PM Inlet

In order to enhance product normalization the filter holder for use with the Mini PM inlet is identical to the one used for the full size EPA inlet. However the mating tenon has been reduced from 1.250 in. outside diameter down to 0.562 in.

Specifications:

References:

1. M. Tolocka, et al, On the Modification of the Low Flow Rate PM 10 Inlet, AS&T, 34: 407-415 (2001)
2, L. Kenny, et al, Aspiration and Sampling Efficiencies of the TSP and Louvered Particulate Matter Inlets,
     J Environ. Monit.,7: 481 - 487 (2005)
3. Marple, V. A., and Rubow, K. L. (1986). Chapter 4: Theory and Design Guidelines.
     In Cascade Impactor: Sampling and Analysis, American Industrial Hygiene Association, edited by J.P. Lodge and T.L. Chan.