Transcript No Slide Title

Measurement of total mass concentration
Sampling
probe
Filter
holder
Flow
regulator
Filter
Screen
Flowmeter
P
Pressure gauge
Vacuum
pump
1. Sampling probe
- Isokinetic or sampling from still air
2. Flow rate
- Rotameter or digital flowmeter
3. Filter
- Nearly 100% efficiency for all size.
- f 13, 25, 37, 47 mm (circular).
- 200 mm x 250 mm (Hi volume sampler).
4. Filter holder
- Open-face: uniorm distribution of particles for analysis in microscope.
- Closed-face: simple, for mass concentration measurement.
Open-face
Closed-face
5. Balance
- Analytical balance, 0.01 to 0.1 mg sensitivity.
- Electrobalance, 0.1 to 10 mg sensitivity.
- Sample should be kept in the room with balance for 1 - 24 hr
until equilibrium.
6. Vacuum pump
- Personal pump; low flow rate 1-4 l/min.
- Larger pumps; 100 l/min.
Diaphragm pump
Blower pump for
Hi-volume sampler
Calculation for mass concentration
m
c
Qt
is concentration
is total mass collected
Q is flow rate
t is sampling time
c
m
Minimum sampling volume
10S
V
c
V is sampling volume
S is sensitivity of balance
c is standard concentration
Personal sampler
- Used in ocupational hygiene to evaluate workers’ exposure to aerosol.
- Measuring in the breathing zone; with 30-cm radius of workers’ mouth.
- Light weight, battery powered pump and plastic filter holder.
- Additional size selective option available; e.g. PM-10.
SKC personal sample.
SKC personal sampler taken apart.
High Volume sampler
- Using 2- or 3-stage centrifugal blower to
pull air in.
- High flow rate: up to 1700 l/min (60 CFM).
- Variable speed motor is used to keep constant
flow rate that may be affected by temperature
and pressure change, or pressure drop due to
dust loading on filter.
- Used 200 mm x 250 mm (8 in x 10 in) glass
fiber filter.
- A roof with 50% for sampling of 30 micron
particle at wind speed of 8 km/hr.
PM-10 & PM-2.5
- Standard in analysis of atmospheric dust issued by the U. S. Environmental
Protection Agency (EPA).
PM-10
- Suspended particle smaller than 10 micron in diameter.
- Respirable; smaller particle travels deeper in respiratory tract.
- Impactor or cyclone can be used to cut off particles greater than 10 micron.
- 24-hr average for 3 samplings in 3 years must not exceed 150 mg/m3.
- Annual average for 24-hr sampling must not exceed 50 mg/m3.
PM-2.5
- Suspended particle smaller than 2.5 micron in diameter.
- For study of small aerosol particles thae affect visibility.
- Particles smaller than 2.5 microns usually composed of SO42-, NO3-, NH4+, and C.
- Toxic metals; Ni, Cd or Cr.
- Organic compounds; Polyaromatic Hydrocarbons (PAH).
Personal sampler for respirable dust
- Using cyclone for size selection.
- Flow rate of 1.9 l/min
PM-10 High Volume Sampler
- For sampling of suspended particles smaller than 10 micron.
PM-10/PM-2.5 Dichotomous Sampler
- Classifying particles in 2 size range; 10 micron and 2.5 micron.
- Using virtual impactor.