NYC-WTC_000220176

NYC 9/11 Public Portal Document «‘C?’^..^nv2ron».nna, Corp Ca 12,75B-0759 • iW* .;P*vAwr'v0 _ p. 15

Scientific Laboratories, lac. .

Collection of Settled Dust for Semi^O^antitative TEM Analysis Sampling for settled dust is a simple and rapid merhod of charaoerizlng surface contamit ants as osbeitos containing dust (ACD) possible asbestos (AOD). Any building„ survey or hazard evaluation sho ild include the ©valuation of all sources of asbestos. Assessment should include setited dust • t • — s_ _ _ _—s . ____A* .J - —A— \ AA M A —.a. . V ..n X )t A A .■ A A© fX

both the subject area and any connected air spaces ox air handling syuems. Ths mcLhcd involves collection of dust from a surface of known area into a TEM air cuss stte containing an MCE filter (see ASTM 1)5755 for more detailed information). The results will be given is terms of structures per square centimeter of surface sampled. The dust is coUec ed by "vscuumiug" a Surface using a .short "collection tube” attached to the inlet of a closed face TEM air cassette. The Size of the "area of coUecrion” (typically 100 cm2 co 1 fti) can^ vary-ftom st mplo to .sample depending upon dust load with larger areas required for cleaner surfaces. For ex iraple, areas heavily loaded with dust tnight require collection areas of 100 cm^, whereas lightly loaded areas might require up to 900 Citf (929 cm2 = 1 R2), Since the sample will be rodeposiu d during preparation, overloading 1$ not a problem us in air samples. Large pieces of debris shou d be .sampled and analyzed separately since they will overshadow the dust if included with tin । dust for analysis. Microvacuuiw Method - .ASTM pg753»9S 1. Determine th© size of surface area to be sampled and designate or roiuk the area tt । be sampled (typically 100 cni^ to i n®). It may bo physically measured and marked or outlined with a template. In some cases, it may be necessary to collect the sampi ; and then measure the ‘‘vacuumed” area, which does not have to be square. Record AREaJ OF COLLECTION on aubtnittal form. 2. Retnove^ttctive plugs from the cassette and attach the hose from the purnp to the cassette. OUTLET (see note below on flow rate). The cassette should, be a commercially; vailable 25mm or 37nun diamour cassette containing an MCE filter of poro Lice O.Sjxm o ■ less. Clear cassettes can be used to allow a qualitative evaluation of sample load dnnn:; coUecrion. Static charge will aot prssenl a problem since the sample material is r nsed from the cassette and collection tube during preparation. 3, Attach the perpendicularly cut end of a clean collecSoc tube to ths cussttre TNLK ?. The collaciion tube should be approximately 1 inch long (25.4mni) with an inside diameter (ID) of 1/4 inch (6.35fnmj. The collection end should be cut at a 45 degree angle wii i the other ©nd cut at a 90 degree angle. The coUectlon tube air velocity of 100 emZs (4-10% is provided at a 2 !itei/min flow rate for Ab 1/4 inch ID tube. If either the tube ID dr flow rat© is differenL Che other should be rraxliRed .accordingly. A cooiEnercially available cassottc/collection rube combination should be used if possible to insure unifem ty of fiber background arid assembly conditions,

SdLab, THM, 2/96 page 1

■

TOTAL P.14

CITY_21MC100_002832776

NYC-WTC_000220176