Cleaning vessels and covers from NOx contamination

TFM vessels and covers, due to their extensive use, could accumulate NOx that could affect the microwave performance (TFM starts absorbing MW).

This mainly occurs in case of digestion temperatures over 200°C and is accelerated by even high temperatures and high pressure.

Microwave absorption test
In order to check, if vessels and covers are contaminated by NOx gases, the following simple test
could be performed

Place the dried rotor body into the microwave and distribute the parts to be tested.
Notice that the parts to be tested must be washed and dried, so that no acid residues may be located on the parts.

Start the following microwave program, depending on the vessels number.
• 45 seconds 600 W (for 10 up to 15 vessels)
• 45 seconds 450 W (for 6 or less vessels)
Once concluded the run, check immediately the temperature with the hands (it would bebetter with thin gloves) or possibly via the IR control. A rough evaluation of the temperature, such as cold/slightly warm/really warm/hot is enough.

Rinse the pre-cleaned vessels with deionized water thoroughly and place them at least for 3 hours in a drying oven (ventilated, if possible) at 160°C.
PTFE vessel should be placed with the opening facing up.
PTFE cover should be placed with the bottom side facing up.