Appendix III: Guidelines for Measuring Sample Bags
The following guidelines are for collecting air samples in standard samples bags. In order to collect an air sample, you must pump air into the bag (pump not included). These bags are often used to collect ambient air samples to analyze later in a laboratory, using a gas chromatograph, or can be connected to the F-900 using the accessory parts.
- Ensure that the bag material and fittings are appropriate for the compounds to be sampled.
- Use only Teflon or Viton tubing to connect the sample bag to the pump to prevent sample loss by adsorption on tubing walls.
- Before using, flush the bag thoroughly with purified air or nitrogen.
- Analyze the sample within 24 to 48 hours. Long-term storage of air-contaminant mixtures in bags is not recommended.
- Do not ship sample bags by air unless the cargo cabin is pressurized.
- Do not overfill sample bags.
- Secure polypropylene value when opening/closing by holding side stem while turning entire upper portion of fitting one revolution.
- Store bags flat. Do not roll or crease bags during storage.
- Do not use bags at temperatures above 140 °F (60 °C).
- Bags are designed for single use only.
To Collect a Sample Using a Sample Bag
Flush the bag at least 3 times with purified air or nitrogen before use.
To fill a bag, connect tubing from the exhaust port of an air sample pump to the hose connection on the bag (stem protruding from the side of the fittings).
To open the shut-off valve, hold the side stem and turn the entire upper portion of the fitting (including the brown syringe port and the white section to which it is attached) counterclockwise one revolution. Turn on the pump and sample.
Avoid filling any bag more than 80% of its maximum volume.
When sampling is complete, turn off the pump. To close the shut-off valve, hold the side stem and turn the entire upper portion of the fitting clockwise until it is snug.
To withdraw samples using a needle and syringe, carefully insert the needle into the septum port in the center of the brown cap and pierce the septum. Do not allow the needle to puncture the bag material when piercing the septum.
Do not use the fitting valve as a handle or hanging device. Although it is durable, it is not intended for these uses.
Analyzing a Sample Bag with the F-900
- Connect the sample bag to the IN port of the F-900.
- Open the sample bag to allow gas to start flowing to the F-900.
- It takes about 3-5 minutes to measure a sample bag if the concentration of ethylene before measuring the sample bag is low.