Background CO pg.1

AN INVESTIGATION INTO THE SOURCES OF BACKGROUND CO IN HEATED FLEXIBLE SAMPLE TRANSPORT HOSE

INDEX
Scope
Summary
Conclusions
Procedure
    TEST 1
    TEST 2
    TEST 3
    TEST 4
    TEST 5
    TEST 6
Results
    TEST 1
        Hose 1
        Hose 2
        Hose 3
        Hose 4
    TEST 2
    TEST 3
    TEST 4
    TEST 5
    TEST 6
Discussion of Method and Error
APPENDIX
    Appendix 5
    Appendix 6
    Appendix 8
    Test Equipment

Scope

The following tests were administered with the goal of determining the source of background CO present in flexible heated sample system hoses.

Summary

Based upon our test results, the CO content rises dramatically with an increase in temperature, starting at about 345 F. Taken and held at 400 F, the CO content continues to raise, peak, then begin a gradual descent.

The major contributors of CO were determined to be the high temperature fiberglass insulation and fiberglass tape, with the kapton tape emitting lower levels. We found no detectable levels emitted from the Teflon tubing, braided metal sheath, or silicone. We conclude that, upon heating, CO is formed from the materials mentioned above. The CO then travels through the silicone, the braided metal sheath, and the Teflon tube into the process gas.

Conclusions

Test 1 had the main objective of determining the levels of CO emission, but also was the objective of eliminating the emission. It was suspected that the CO would "burn off" after a relatively short period of time. Hose 2 proved this wrong. Hose 2 was monitored for approximately 53 hours only to show a minimal decrease in CO emission. Test 1 also opposed the theory that oil on the metal sheathing was responsible for CO emission due to the fact that Hose 3 and 4 had similar results, while Hose 3 was cleaned of oil and 4 was tested as received from the vendor.

Test 3 indicated the major CO contributors. This included fiberglass insulation (high temp.), fiberglass tape, and kapton tape.

Test 4 indicated that the Teflon tube and metal sheath are not responsible for CO production.

Test 5 demonstrated how the CO travels through the silicone, Teflon tubing, and metal sheath.

Test 6 suggests that the metallic barrier greatly hinders the migration of CO into the process gas. Spikes did occur, however, when the hose was heated with no gas flow. This would indicate that CO continues to travel through the mylar, but at a much lower rate than previously.

When the unheated core was isolated, no CO levels were detected. This supports the theory that the CO migration is directed toward the heat source.

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