The Hong Kong Polytechnic University Department of Civil and Structural Engineering Civil Engineering (31072–2) CSE331 --- Air & Noise Pollution Studies October 2011 i Laboratory Report for Air Pollution Experiment 1a: Gas Pollutant Measurement Experiment 1b: Determination of Suspended Particulates Using HighVolume Sampler Student Name (ID) : Programme Code : 31072 2 Subject Code : CSE331 Air & Noise Pollution Studies Lecturer : Dr. H. Guo Date of Laboratory Test : 29Sep2011 Date of Report Submission : 14Oct2011
Transcript
The Hong Kong Polytechnic University Department of Civil and Structural Engineering Civil Engineering (31072–2) CSE331 --- Air & Noise Pollution Studies
October 2011 i
Laboratory Report for Air Pollution
Experiment 1a: Gas Pollutant Measurement Experiment 1b: Determination of Suspended Particulates Using High-‐Volume
Sampler Student Name (ID) : Programme Code : 31072 -‐ 2 Subject Code : CSE331 Air & Noise Pollution Studies Lecturer : Dr. H. Guo Date of Laboratory Test : 29-‐Sep-‐2011 Date of Report Submission : 14-‐Oct-‐2011
The Hong Kong Polytechnic University Department of Civil and Structural Engineering Civil Engineering (31072–2) CSE331 --- Air & Noise Pollution Studies
October 2011 ii
TABLE OF CONTENT TOPIC DESCRIPTIONS PAGE 1. Gas Pollutant Measurement (Using Teflon/Tedlar Bag) .................................................... 1
1.1. Objective ............................................................................................................ 1 1.2. Apparatus ........................................................................................................... 1 1.3. Procedures ......................................................................................................... 1 1.4. Sampling location ............................................................................................... 2 1.5. Experiment result data ....................................................................................... 3 1.6. Questions and Answers for experiment 1a ........................................................ 4
2.4. Experiment result data ....................................................................................... 6 2.5. Questions and Answers for experiment 1b ........................................................ 8
The Hong Kong Polytechnic University Department of Civil and Structural Engineering Civil Engineering (31072–2) CSE331 --- Air & Noise Pollution Studies
October 2011 1 of 9
1. Gas Pollutant Measurement (Using Teflon/Tedlar Bag)
1.1. Objective To carry out spot measurement around Polytechnic University by means of sampling bag method for collecting gas pollutants at different locations. 1.2. Apparatus
1. Gas analyzer for SO2, NOX and CO measurement. 2. Tedler sampling bag 3. Constant flow sampling pump 4. Teflon tubing
1.3. Procedures
- Go to designated sampling location (Fig 1 in P. 2) - Point inlet tubing at working level near pollution source. - Let the sampling pump free run for equilibrium the sampling line at least one minute. - Switch off the pump. Connect Teflon tubing from pump bag is closed. (Hold bag inlet
fitting and turn valve body for either open or close the valve). - Switch on the pump for desired averaging time period, after time finished. - Switch off the pump again. Closing the bag valve by one full right run. Disconnect tubing
from bag inlet fitting. - Adjustment of the sampling flow rate for desired averaging time period shown below:
-‐ Averaging time period (T) = 5 minutes -‐ Sampling bag capacity (V) = 12 litres -‐ Total volume of sample must not greater than 12 litres -‐ Flow rate (Q) should be set lower than V/T = 2.4 LPM -‐ The optimum flow rate for this example is 2 LPM
- Go to anther sampling location for taking gas sample again - Bag sample should be taken back to laboratory for further analysis as soon as possible.
The Hong Kong Polytechnic University Department of Civil and Structural Engineering Civil Engineering (31072–2) CSE331 --- Air & Noise Pollution Studies
October 2011 2 of 9
1.4. Sampling location Fig 1 –
Sampling location in Campus
The Hong Kong Polytechnic University Department of Civil and Structural Engineering Civil Engineering (31072–2) CSE331 --- Air & Noise Pollution Studies
October 2011 3 of 9
1.5. Experiment result data Date 26th September 2011 Weather condition Fine Location (Fig 1 in P. 2) 1 2 3 4 5 Remarks (Any activity takes place nearby?)
No No No No No
1. SO2 (ppb) 3.5 2.6 5.9 4.2
2. NO 153.2 37.8 91.7 284.1
3. NO2 (ppb) 60.4 33.3 38.6 57.9
4. CO (ppm) 917.5 550.2 893.7 2078.9 Date 26th September 2011 Weather condition Fine Location (Fig 1 in P. 2) 6 7 8 9 10 Remarks (Any activity takes place nearby?)
No No No No
1. SO2 (ppb) 3.2 2.9
2. NO 29.6 63.6
3. NO2 (ppb) 24.0 51.3
4. CO (ppm) 481.5 833.9
The Hong Kong Polytechnic University Department of Civil and Structural Engineering Civil Engineering (31072–2) CSE331 --- Air & Noise Pollution Studies
October 2011 4 of 9
1.6. Questions and Answers for experiment 1a 1. What is the advantage and disadvantage of using sampling bag for collecting gas sample? Answer: The advantages of using sampling bag are very easy and convenience to collect gas sample. This method can easy to obtain the air pollutants without using complex devices. The costs of using sampling also lower than other method. The disadvantages of using sampling are fair surface inertness and indefinite hold time when collecting gas sample. Human error may sometimes occur, the gas sample may not steady for such a short time to collect the air. When collecting trace compound in atmosphere, we need to clean the tubing every time we use, or replace the tube after several time used. 2. Compare the measurement results at different locations and suggest reasons if there is
variation in the results? Answer: From the experimental result data, It is easy to see that Location 4 and 5 have a higher NO concentration than other locations. The reason of this may due to location 4 and 5 are need the working site of POLYU and also a highway next to it. This also prove that why the CO value is much higher than lcoation 2,7 and 8. While location 1 are also located above a bus stop and the traffic jam of Hung Hom Cross Harbour Tunnel. CO and NO are higher than location 7 and 2 while is much near the school campus. Result finds out that the NO2 and SO2 concentration are quite similar for all the location we have measured in this laboratory. Mostly because government have control the emission of these two pollutant. These are only based emission from the combusion source.
The Hong Kong Polytechnic University Department of Civil and Structural Engineering Civil Engineering (31072–2) CSE331 --- Air & Noise Pollution Studies
October 2011 5 of 9
2. Determination of Suspended Particulates (Using High-‐Volume Sampler)
2.1. Objective
1. To calibrate a high-‐volume sampler 2. To determine the mass concentration of suspended particulates in ambient air
2.2. Apparatus
1. High volume sampler with flow recording device 2. Differential manometer 3. Analytical balance 4. Orifice calibration unit 5. Glass-‐fiber filters
2.3. Procedures 2.3.1. Calibration
- Assemble the high-‐volume sampler with a clean filter in place and run for at least 5 minutes.
- Shut off the motor, remove the filter, and attach the orifice calibration unit in its place. - Operate the high-‐volume sampler at a series of different, but constant airflows. - Record the reading of the differential manometer on the orifice calibration unit, and
record the reading of the flow-‐recording device attached to the high-‐volume sampler. - Convert the differential manometer reading to m3/min, Q, using the correlation curve
provided by the manufacturer. Plot the flow recorder device reading versus Q. 2.3.2. Sampling
- The particulate sample has been collected and equilibrated. Initial filter weight, Initial flow rate, Final flow rate and sampling time can be obtained by air laboratory.
- Weigh the filter to the nearest milligram (final weight). - Convert the flow rate readings to actual flow rate form the calibration curve. - Calculate the mass concentration of the suspended particulates.
The Hong Kong Polytechnic University Department of Civil and Structural Engineering Civil Engineering (31072–2) CSE331 --- Air & Noise Pollution Studies
October 2011 6 of 9
2.4. Calibrate a high volume sampler Particulate Measurement DataDate: 26 September 2011Class: 31069-2A&C/31072-2AOrifice Serial Number : 49A
The Hong Kong Polytechnic University Department of Civil and Structural Engineering Civil Engineering (31072–2) CSE331 --- Air & Noise Pollution Studies
October 2011 7 of 9
2.5. Experiment result data
Sampler Model PM 10 Initial weight of filter(g), Wi 4.5011 Final weight of filter(g), Wf 4.5858 Total sampling time (min), T 1221 Average flow rate, Qavg (CFM) 37.5 Corrected flow rate (CFM) 15.4427 Corrected flow rate (m3/min) 0.4370 Air volume sampled (m3), V 533.6117 Wf – Wi 0.0847 RSP (µg/m3) 158.73 Note: Qavg = (Qf + Qi)/2, V = Qavg x T The mass concentration of the suspended particulate is 158.73 µg/m3
Calculation:
RSP(µg/m3) = [Wf-‐Wi x 106 ] / V V = [Qi + Qf] / 2] x T
Where Wi = Initial weight of filter (g)
Wf = Final weight of filer (g)
V = Air volume sampled (m3)
Qi = Initial air flow rate (m3/min)
Qf = Final air flow rate (m3/min)
T = Sampling time (min)
The Hong Kong Polytechnic University Department of Civil and Structural Engineering Civil Engineering (31072–2) CSE331 --- Air & Noise Pollution Studies
October 2011 8 of 9
2.6. Questions and Answers for experiment 1b 1. Particulate concentration by the high-‐volume method has been doubled because of several
sampling errors. Suggest some of these errors. Answer: Particulate concentration by the high-‐volume method has been doubled because of several sampling errors. These errors are timing of each step, inherent sources, airflow variation etc. Timing of each step cannot be counted very well. Inherent Sources of Error may be occurring inside the devices. The weight of material collected on the filter represents the (integrated) sum of the product of the instantaneous flow rate times the instantaneous particle concentration. Therefore, dividing this weight by the average flow rate over the sampling period yields the true particulate matter concentration only when the flow rate is constant over the period. The error resulting from a not constant flow rate depends on the magnitude of the instantaneous changes in the flow rate and in the particulate matter concentration. However, such errors may not large, but we can be greatly reduced by equipping the sampler with an automatic flow controlling mechanism that maintains constant flow during the sampling period to solve such errors.
The Hong Kong Polytechnic University Department of Civil and Structural Engineering Civil Engineering (31072–2) CSE331 --- Air & Noise Pollution Studies
October 2011 9 of 9
2. Comparing the measurement results you obtained with Hong Kong Air Quality Objective (HKAQO).
Answer: Refer above calculation, we found that the concentration of Respirable Suspended Particulates is 158.73 µg/m3. Accordance with the table of Hong Kong Air Quality Objectives, the average value of RSP is 180µg/m3 in 24 hours, we saw that the concentration of RSP were taken in Polytechnic University were lower than 180µg/m3, it implied that the air quality is in good condition when we were taking data on 26-‐September-‐2011 . The following factors may be affect the concentration of RSP, 1. The concentration of RSP measured
by EPD is at 298K and 101.325 kPa. There are some different with our measurement.
2. Location of High-‐volume Sampler is near the cross habour tunnel, high traffic volumn may be affect the result, also the construction site which is near us may be increase the concentration of pollutant.
![[Venture Lab] Jets - OAP final report](https://static.documents.pub/doc/80x56/55618b2ed8b42ae27d8b4b08/venture-lab-jets-oap-final-report.jpg)
