NSF/GLOBE Project

July, 1995
NSF/GLOBE Research Team
University of Kansas
4002 Learned Hall
Lawrence, KS 66045

Purpose

The purpose of this standard operating procedure (SOP) is to establish a uniform technique for the collection of whole air samples using Summa polished stainless steel (S.S.) canisters by various techniques, used mainly by personnel involved in the NSF/GL OBE research project.

This SOP is a modification of SOP No. MA552A (September 28, 1989) developed by the U.S. Environmental Protection Agency, Region VII and the University of Kansas.

Sampling Procedures

The S.S. canisters offer flexibility when used to collect air samples. There are three primary modes of use and all three may be incorporated into the NSF/GLOBE research project for the collection of ambient air samples. These include: 1) grab sampling of ambient air samples, 2) short term, time integrated ambient air samples, and 3) long term, time integrated ambient air samples.

Ambient air sampling must be done with Summa polished S.S. canisters that have been cleaned and evacuated to 0.05 mm of mercury or approximately 0-20 millitorr according to the canister cleaning procedure referenced earlier.

For grab sampling of ambient air samples, the upper valve of the clean evacuated canister is opened (by turning counter clock wise) to the atmosphere containing the trace gases (methane (CH4), carbon dioxide (CO2), hydroflourocarbons (HFCs)) for 10 to 30 seconds after the brass screw-on cap is removed from the upper valve of the S.S canister (turn the brass cap counter clockwise). A hissing sound should be audible at the intake to the valve when it is opened by the user. It is very important that the ind ividual opening the canister does not breath into the canister inlet while the sample is being taken. With this sampling technique, one individual should be responsible for sample collection and all other individuals observing the collection process shou ld stay away from the canister. The differential pressure between the canister and the atmosphere causes the ambient air sample to flow into the canister. The valve is closed after sampling. Since there are no system elements upstream of the canister ( i.e., flow controllers, sampling pumps, sample intake tubes) with which the sampled air may come into contact, this type of air sampling minimizes the possibility of sample contamination or sampling artifact carry-over. It can be used in almost any envir onmental condition. After the sample is collected, the individual(s) collecting the sample should record the date, weather conditions, time and location the sample was collected on the form provided with the canister. Any abnormalities surrounding the s ample collection event should also be recorded on the form (i.e. no hissing sound when the valve was opened; the valve did not seem to be tightly closed when opened for sample collection). The S.S. canister is put back into the shipping carton after the brass screw-on cap is put back onto the upper valve of the S.S. canister (it should be tightened snugly) and shipped to the NSF/GLOBE research laboratory for analysis along with the sample collection form using the shipping label supplied in the shipping carton. Figure 1 shows the schematic diagram of the grab sampling system using S.S. canisters.

The second method for whole air sampling (short term, time integrated ambient air sampling) uses a mechanical variable flow controller (Veriflo Model #SC-4235XFT-B stainless steel version from Scientific Instrumentation Specialists, Moscow, Idaho or its e quivalent) attached to the canister sample intake line (upper valve). The low pressure side of the flow controller must be toward the canister. This can be determined by looking at the flow controller before it is attached to the canister. There is an arrow on the flow controller. The head of the arrow should point towards the canister inlet when the flow controller is installed properly. The connections are made using 1/4 inch swagelok fittings. The air flow controllers are calibrated by the NSF/GL OBE canister providers in the laboratory using a bubble meter. Flow controllers used in this study will be calibrated at a flow rate of 250 ml/minute. A pressure gauge and the flow controller are connected together with a swagelok "T". Before attaching the swagelok "T" assembly, you should make sure the on/off valve (next to the flow controller) is in the off position (the handle of the on/off valve is turned so it is perpendicular to the swagelok "T" assembly). The swagelok "T" is connected to the up per valve of the canister after the brass screw-on cap is removed from the upper valve of the S.S. canister. Sample collection is started by an individual opening the upper valve of the canister (turning the valve counterclockwise) and then turning the o n/off valve next to the flow controller (see Figure 2) to the on position (the handle of the on/off valve is turned so it is in-line with the swagelok "T" assembly). The individual(s) starting the sampler should observe and record the internal vacuum in the sampler immediately after opening the valve by reading the value on the pressure gauge. If this value for pressure is not approximately 30 inches of mercury vacuum, the sampling activity should be terminated at this point and the sampling system retur ned to the NSF/GLOBE research laboratory as described later in this paragraph. This pressure reading, as well as the start time, sample collection location, sampling date and weather conditions should be recorded on the sheet provided with the canister. Any abnormalities surrounding the sample event (i.e. upper valve was not closed; pressure gauge did not change) should also be noted on the form. At the end of a 12 minute period, the upper canister valve is closed. This ends the sample collection peri od. The individual(s) collecting the sample should record the pressure reading on the pressure gauge, the stop time, the sampling date, the sample collection location and the weather conditions on the form provided with the canister. The swagelok "T" (w ith attached pressure gauge and flow controller) is removed from the canister and both the canister and swagelok "T" assembly is put back into the shipping carton after the brass screw-on cap is put back onto the upper valve of the S.S. canister (it shoul d be tightened snugly) and shipped to the NSF/GLOBE research laboratory for analysis along with the sample collection form using the shipping label supplied in the shipping carton. Figure 2 shows the schematic diagram of a S.S. canister sampling system us ing a flow controller assembly.

The third method of ambient air sampling will be used when longer-term, time integrated samples or higher volume samples are required. In this case, a mechanical flow controller and a fixed volume metering pump (Scientific Instrumentation Specialists, Inc., Model No. N-05SVI, 12 Volts DC with viton diaphragm or its equivalent) are used. The pump will be powered by a fully charged 12VDC battery pack. The flow controller and pump assembly are connected to the S.S. canister inlet (upper valve) with a teflon tube after the brass screw-on cap is removed from the upper valve of the S.S. canister. The teflon tube has 1/4 inch swagelok fittings on each end. A pressure gauge is attached to the swagelok fitting on the lower valve of the S.S. canister after the brass screw-on cap is removed from the lower valve of the S.S. canister. The lower valve is then opened (turn valve counter clockwise) so that the pressure in the canister can be monitored. If this value for pressure is not approximately 30 inches of mercury vacuum, the sampling activity should be terminated at this point and the sampling system returned to the NSF/GLOBE research

laboratory as described later in this paragraph. The 12VDC battery is then hooked up to the pump electrical terminals. The positive terminal of the battery is attached to the positive terminal on the pump and the negative terminal of the battery to the negative terminal of the pump. The air flow controller is calibrated by the NSF/GLOBE canister providers in the laboratory using a bubble meter. Flow controllers used in this study for this sampling method will be calibrated at a flow rate of 500 ml/minute. Sample collection is started by an individual opening the upper valve of the canister (turning the valve counter clockwise) while the pump is running (start pump - connect electric wires - approximately 10 seconds before upper valve is opened). The individual(s) starting the sampler should observe and record the internal vacuum in the sampler immediately after opening the upper valve by reading the value on the pressure gauge (located on lower valve). This pressure reading, as well as the start time, sample collection location, sampling date and weather conditions should be recorded on the s heet provided with the canister. Any abnormalities surrounding the sample event (i.e. upper valve was not completely closed when you initially opened it, pressure gauge did not change value when the lower valve was opened) should also be noted on the for m. At the end of a 12 minute sampling period, the upper canister valve and the lower canister valve are closed (turn valves clockwise until they are snug). This ends the sample collection period. Turn off the mechanical pump by disconnecting the electr ic wires. The individual(s) collecting the sample should record the final pressure reading on the pressure gauge, the stop time, the sampling date, the sample collection location and the weather conditions on the form provided with the canister. Remove the pressure gauge from the lower valve and the teflon sample line from the upper valve. The canister is put back into the shipping carton after the brass screw-on cap is put back onto both the upper and lower valves of the S.S. canister and shipped to t he NSF/GLOBE research laboratory for analysis along with the sample collection form using the shipping label supplied in the shipping carton. Put the pressure gauge and pump/flow controller in a safe place for the next sample event and recharge the 12VDC battery pack as per the instructions on the battery charger provided with the battery pack. Figure 3 shows the schematic diagram of an air sampling system with flow controller and pump attached to the S.S. canister.

Sampling Location

A location for sample collection should be chosen with some care. It is important that the sample not be collected next to a major air pollution source. These would include highways, roads, buildings, industries, sidewalks etc. Try to locate the sample r in a vegetated area free of pedestrians. If possible, the sample should be taken at a height of 1 1/2 meters to 2 meters above ground level. You can set the sampler on a stool, step ladder or other stand; but try to avoid holding it in your hand. An ideal sampling location would be a large, grass covered field with a minimum of surrounding person made activities.

References

The sampling will be performed with a clean, evacuated S.S. canister as supplied by the NSF/GLOBE research team. Prior to sample collection the canisters will be cleaned and evacuated to less than 20 millitorr (0.05mm of mercury) using a standard operati ng procedure developed at the University of Kansas in cooperation with the U.S. Environmental Protection Agency, Region VII (SOP No. MA551A, June 21, 1989).

Standard Operating Procedure for Air Sampling with a Stainless Steel Canister - Student Version

NSF/GLOBE Project
July, 1995
NSF/GLOBE Research Team
University of Kansas
4002 Learned Hall
Lawrence, KS 66045
Purpose

The purpose of this standard operating procedure (SOP) is to establish a uniform technique for the collection of whole air samples using Summa polished stainless steel (S.S.) canisters by various techniques, used mainly by personnel involved in the NSF/GL OBE research project.

This SOP is a modification of SOP No. MA552A (September 28, 1989) developed by the U.S. Environmental Protection Agency, Region VII and the University of Kansas.

Sampling Procedures

The S.S. canisters offer flexibility when used to collect air samples. There are three primary modes of use and all three may be incorporated into the NSF/GLOBE research project for the collection of ambient air samples. These include: 1) grab sampling of ambient air samples, 2) short term, time integrated ambient air samples, and 3) long term, time integrated ambient air samples. Ambient air sampling must be done with Summa polished S.S. canisters that have been cleaned and evacuated to 0.05 mm of mer cury or approximately 0-20 millitorr according to the canister cleaning procedure referenced earlier.

Procedures for grab sampling:

1. Remove the brass, screw-on cap from the upper valve of the S.S. canister.

2. Open (by turning it counter clockwise) the upper valve of the clean evacuated canister for 10 to 30 seconds. A hissing sound should be audible at the intake to the valve when it is opened by the user. Be careful not to breath into the canister inlet w hile the sample is being taken. Keep individuals away from the canister during sample collection.

3. Close (by turning it clockwise) the upper valve of the S.S. canister.

4. Record (on the form provided with the canister) the date, weather conditions, time and location the sample was collected. Any abnormalities surrounding the sample collection event should be recorded on the form (i.e. no hissing sound when the valve wa s opened; the valve did not seem to be tightly closed when opened for sample collection).

5. Replace the brass, screw-on cap onto the upper valve of the S.S. canister (it should be tightened snugly).

6. Put the S.S. canister back into the shipping carton.

7. Put the sample collection form into the shipping carton.

8. Affix the preaddressed, prepaid shipping label in the shipping carton to the outside of the shipping container.

9. Secure shipping container with shipping quality tape (duct tape works fine).

10. Ship the carton to the NSF/GLOBE research laboratory.

Second Technique - Short Term, Time

Integrated Sampling Method

Procedure for short term, time integrated sampling method:

1. Remove the brass, screw-on cap from the upper valve of the S.S. canister.

2. Before attaching the swagelok "T" assembly to the upper valve of the S.S. canister, make sure the on/off valve (next to the flow controller) is in the off position (the handle of the on/off valve is turned so it is perpendicular to the swagelok "T" ass embly).

3. Attach the swagelok "T" assembly to the upper valve of the canister (it should be tightened snugly).

4. Open (by turning it counter clockwise) the upper valve of the clean, evacuated canister.

5. Observe and record on the form provided with the canister the internal vacuum in the sampler by reading the value on the pressure gauge. If this value is not approximately 30 inches of mercury vacuum, terminate the sampling activity at this point and skip to step 10.

6. Turn the on/off valve (next to the flow controller) to the on position (the handle of the on/off valve is turned so it is in-line with the swagelok "T" assembly).

7. At the end of a 12 minute time period, close the on/off valve by turning it so the on/off valve handle is perpendicular to the swagelok "T" assembly.

8. Close the upper valve of the S.S. canister.

9. Observe and record on the form provided with the canister the internal vacuum in the sampler by reading the value on the pressure gauge.

10. Record (on the form provided with the canister) the start time, sample collection location, sampling date, weather conditions and the stop time. Any abnormalities surrounding the sample collection event should be recorded on the form (i.e. upper valv e did not seem to be tightly closed when opened for sample collection; the reading on the pressure gauge did not change in value from start to finish).

11. Remove the swagelok "T" assembly from the canister.

12. Replace the brass, screw-on cap onto the upper valve of the S.S. canister (it should be tightened snugly).

13. Put the S.S. canister and the swagelok "T" assembly back into the shipping carton.

14. Put the sampling collection form into the shipping carton.

15. Affix the preaddressed, prepaid shipping label in the shipping carton to the outside of the shipping container.

16. Secure shipping container with shipping quality tape (duct tape works fine).

17. Ship the carton to the NSF/GLOBE research laboratory.

Third Technique - Long/Term High Volume - Sampling Method

Procedures for long term/high volume sampling:

1. Remove the brass, screw-on cap from the upper and lower valve of the S.S. canister.

2. Attach the teflon tube from the fixed volume metering pump to the upper valve of the S.S. canister (it should be tightened snugly).

3. Attach the pressure gauge to the lower valve of the S.S. canister (it should be tightened snugly).

4. Open the lower valve of the S.S. canister.

5. Record (on the form provided with the canister) the internal vacuum in the sampler by reading the value on the pressure gauge. If this value is not approximately 30 inches of mercury vacuum, terminate the sampling activity at this point and skip to st ep 12.

6. Hook-up the 12 VDC battery to the pump electrical terminals. The positive terminal of the battery is attached to the positive terminal on the pump and the negative terminal of the battery to the negative terminal of the pump.

7. Open (by turning it counter clockwise) the upper valve of the clean, evacuated canister while the pump is running.

8. At the end of a 12 minute time period, close (by turning it clockwise) the upper valve of the S.S. canister.

9. Close (by turning it clockwise) the lower valve of the S.S. canister.

10. Record (on the form provided with the canister) the internal vacuum in the sampler by reading the value on the pressure gauge attached to the lower valve of the S.S. canister.

11. Turn off the sampling pump by disconnecting the electric wires.

12. Disconnect the teflon sampling tube from the upper valve of the S.S. canister.

13. Disconnect the pressure gauge from the lower valve of the S.S. canister.

14. Replace the brass, screw-on caps onto the upper and lower valves of the S.S. canister (they should be tightened snugly).

15. Record (on the form provided with the canister) the start time, sample collection location, sampling date, weather conditions and the stop time. Any abnormalities surrounding the sample collection event should be recorded on the form (i.e. pressure g auge reading did not change when it was initially opened; the sampling pump would not start; the upper and/or lower valve did not seem to be tightly closed when initially opened).

16. Put the S.S. canister back into the shipping carton.

17. Put the sample collection form into the shipping carton.

18. Affix the preaddressed, prepaid shipping label in the shipping carton to the outside of the shipping container.

19. Secure shipping container with shipping quality tape (duct tape works fine).

20. Ship the carton to the NSF/GLOBE research laboratory.

21. Store the pressure gauge and pump/flow controller in a safe place until the next scheduled sampling event.

22. Recharge the 12 VDC battery pack as per the instructions on the battery charger provided with the battery pack.

Sampling Location

A location for sample collection should be chosen with some care. It is important that the sample not be collected next to a major air pollution source. These would include highways, roads, buildings, industries, sidewalks etc. Try to locate the sample r in a vegetated area free of pedestrians. If possible, the sample should be taken at a height of 1 1/2 meters to 2 meters above ground level. You can set the sampler on a stool, step ladder or other stand; but try to avoid holding it in your hand. An ideal sampling location would be a large, grass covered field with a minimum of surrounding person made activities.

References

The sampling will be performed with a clean, evacuated S.S. canister as supplied by the NSF/GLOBE research team. Prior to sample collection the canisters will be cleaned and evacuated to less than 20 millitorr (0.05mm of mercury) using a standard operati ng procedure developed at the University of Kansas in cooperation with the U.S. Environmental Protection Agency, Region VII (SOP No. MA551A, June 21, 1989).