DEPARTMENT OF ECOLOGY

SOURCE TEST METHOD

METHOD 18, PARTICULATE MEASUREMENT USING AN INTERMEDIATE VOLUME
SAMPLER

1. Principle

Particulate emissions are determined by filtration using an I ntermediate V olume S ampler (IVS).

2. Description

Exhaust gas is withdrawn from a duct approx imately isokinetically. The particulate is collected on a glass fiber filter and the sa mple volume determined by a flowmeter and lapsed time. The concentration is then calcu lated by dividing the we ight of particulate collected by the volume sampled.

3. Equipment

Sampler -- IVS particulate sampler, as shown in Figure 1 and described in "Particulate Sampling with a Compact Intermediate Vo lume Sampler" by G.S. Beckwith, APCAPNWIS, November) 1974. The sampler consists of the following: (a) nozzle, (b) probe with flowmeter and thermocoupl e (c) filter holder (d ) variable speed blower, variable from 2 to 20 cfm, and (e) lapsed time meter.

Filter -Glass fiber mat filte r of pyrex without organic binder (Gelman Type A or equivalent) filter container.

4. Procedure

After selecting the sampling site, determine the exhaust temperature, moisture and velocity. These values should be measure d, but under some conditions, they may be estimated. Using the average velocity determin ed above, select a nozzle size and pressure drop ( △ h) from Tables 1 to 5 that would re sult in isokinetic sampling. Ideally, the sampling rate should be between 10 and 20 cfm. Then assemble the sampler as shown in Figure l, placing two pre-weighe d filters in the filter hold er section. Normally, select three or four sampling points and adjust the sa mpling rate to the average velocity in the duct. In no case should zero or negative velocity areas be sampled. Drawing clean ambient air through the sampler, set the contro l switch in the variab le mode and quickly adjust to the selected ∈ h and turn off the sampler.

Zero the lapsed time meter. Insert the nozzl e into the gas stream and position the nozzle at the desired sampling point. Then turn the sa mpler on to the variable mode and adjust to the selected flowmeter pressure drop ∈ h. Sample for a minimum of three minutes and record simultaneous readings of lapsed time, △ h and sample temperature periodically. Normally, readings are taken every minute, or five readings during the run. If necessary, the sampling should be adjusted to maintain the desired △ h. Terminate the run if unable

to maintain half of the desired △ h. At the end of the run, record the final elapsed time,
△ h and temperature.Carefully remove the filters a nd place them in a pre-weighe d container. Al so, brush any loose particulate from the nozzle, probe and filter holder into the container.

5. Analysis

Dry the sample in a pre-weighed container at 105 o C and desiccate until cool. Then weigh the sample on an analytical balance.

Calculate the sample volume from the product of the sampling rate and the lapsed time. If the sampling rate was not constant, calcula te the volume sampled for each increment of lapsed time recorded and add the increments . Then divide the weight of particulate collected by the volume sampled corr ected to standard dry conditions.Figure 1. Intermediate Volume SamplerMethod 18