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get a zero reading, proceed. If you don’t get a zero reading,
suspect a leak.
◆ Start volatilizer and heat water to 200 °F or above. A minimum
temperature of 150 °F is required at all times during the
introduction process.
◆ Place fumigant cylinder with gas introduction line on scale and
take initial weight reading. Make sure the gas introduction line is
attached to the cylinder. After obtaining the correct weight,
subtract the dosage to be introduced into the enclosure. After
you have introduced the proper amount of gas, the scale will be
balanced.
◆ Check that container is placarded and the area is secured. Only
people working on the fumigation may be in the area.
◆ Check container to make sure it is free from holes where MB
might leak.
◆ Check that all gas sampling tubes are labeled and are not
crimped or crushed. Inspect tubes visually, or use an electric or
Mityvac hand pump to check tubes. Either a fumiscope or
vacuum pump may be used to test leads for unrestricted flow.
dosage (lbs.) = volume(ft3) × dosage rate (lbs./1,000 ft3)
volume(ft3) × dosage rate (lbs.)
1,000 ft3
= -----------------------------------------------------------------------------
Chemical Treatments Fumigants • Methyl Bromide • Special Procedures for Container Fumigations Without a Tarpaulin
Conducting the Fumigation
2-8-12 Treatment Manual 10/2002-04
PPQ
The Center for Plant Health Science and Technology (CPHST) has
developed the following procedure to detect blocked monitoring leads
with the use of a Mityvac hand-held pump (for supplier, see Vacuum
Pump, Appendix 8):
1. Prior to fumigant introduction, connect the Mityvac hand-held
vacuum pump to a monitoring lead.
2. Squeeze the handle on the Mityvac unit. If the lead is blocked, a
vacuum will be indicated on the vacuum gauge of the Mityvac
unit. (The handle should be squeezed two or three times for
monitoring leads longer than 25 feet. The Mityvac hand-held
pump has the capacity to attain and hold 25 inches of Hg
vacuum and a minimum of 7 psig pressure.)
3. Disconnect the Mityvac hand-held pump from the monitoring
lead, and repeat this procedure for each monitoring lead.
(Connect monitoring leads to the gas analyzer prior to fumigant
introduction.)
◆ Check that there is enough gas in the cylinder and if necessary,
that other cylinders are available.
◆ Check the gas introduction line connections to make sure they
are tight and free of leaks (wearing the SCBA).
◆ Check all safety equipment, especially SCBA, is available and in
working order.
◆ Install Drierite® tube on gas sample line attached to the T/C unit
and check to make sure granules are blue, if pink—replace
Drierite®. If humidity is high, additional Drierite® tubes or
frequent changes may be necessary.
Conducting the Fumigation
Step 1—Introducing the Gas
Important
When conducting fumigations with methyl bromide, sulfuryl fluoride or
phosphine, erroneous readings may occur if the monitoring leads become
blocked or crimped. It would be impossible to install a new monitoring lead
during a fumigation treatment. Therefore, to avoid an unsuccessful fumigation,
you should test monitoring leads before the treatment begins.
The acceptable air concentration level for methyl bromide (MB) is 5 ppm. A
respirator (approved SCBA or MSHA/NIDSH) is required if the MB
concentration level in the air is greater than 5 ppm at any time. You and the
fumigator must use your SCBA while introducing the gas, checking for leaks,
and when taking aeration readings.
Chemical Treatments Fumigants • Methyl Bromide • Special Procedures for Container Fumigations Without a Tarpaulin
Conducting the Fumigation
10/2002-04 Treatment Manual 2-8-13
PPQ
Turn on all fans before introducing the gas. When using large
cylinders of MB, have the fumigator open the cylinder valve slightly,
then close the valve. With a halide detector, check all connections on
the gas introduction line for leaks. If leaks are found, advise the
fumigator tighten the connections and repeat the test. If no leaks are
found, then open the valve to the point where 3 to 4 pounds of MB are
being introduced per minute. The water temperature in the volatilizer
should never go below 150 °F at any time during gas introduction. The
water in the volatilizer may include an antifreeze and should be
handled with the appropriate safeguards.
The fumigation time begins once all the gas has been introduced.
Record the time gas introduction was started and completed in Block
32 on the PPQ Form 429. Run the fans for 30 minutes to achieve even
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