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 Intermediate Volume Sampler 

(IVS). 

2. Description

Exhaust gas is withdrawn from a duct approximately isokinetically. The particulate is 

collected on a glass fiber filter and the sample volume determined by a flowmeter and 

lapsed time. The concentration is then calculated by dividing the weight 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 Volume Sampler" by G.S. Beckwith, APCAPNWIS, November) 1974. The sampler consists of the following: (a) nozzle, (b) probe 

with flowmeter and thermocouple (c) filter holder (d) variable speed blower, variable 

from 2 to 20 cfm, and (e) lapsed time meter. 

Filter -Glass fiber mat filter 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 measured, but under some conditions, they may be 

estimated. Using the average velocity determined above, select a nozzle size and pressure 

drop (△h) from Tables 1 to 5 that would result 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-weighed filters in the filter holder section. Normally, select 

three or four sampling points and adjust the sampling 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 control switch in the variable mode and quickly 

adjust to the selected ∈h and turn off the sampler. 

Zero the lapsed time meter. Insert the nozzle into the gas stream and position the nozzle 

at the desired sampling point. Then turn the sampler 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 and place them in a pre-weighed container. Also, 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 105o

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, calculate 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 corrected to standard dry conditions. 





Figure 1. Intermediate Volume Sampler 

Method 18