Frequent Questions

What are the requirements for documenting the tumbling rate for TCLP extractions?

What are the recommendations or requirements for documenting the tumbling rate for TCLP extractions (e.g., on a daily basis, annual basis, etc.)? We know the equipment is typically within range since they are simple motors and if there are problems they seem to be very apparent (not rotate at all).


The rotation speed of the tumbling apparatus must be within specifications of 28-32 rotations per minute. At a minimum, this should be checked at the start of the extraction and recorded with every batch as you would record the temperature and rotation time. Depending on the apparatus type, you may want to record the rpm at the end of rotation as well to assure the apparatus was stable. This check can be done in 30 seconds looking for 14-16 rotations.

Many tumblers have safety features built in like a friction clutch that allows slippage, should an arm, leg, or loose clothing get caught during rotation. Those clutches can become loose over time and rotations may be slower or stop, even though the motor is turning normally. Rotations should be checked under full load as the extra weight may cause slippage, whereas an empty tumbler may rotate acceptably. Friction clutches can also loosen when the motor is shut off and the rotator is moved by hand to a position that allows loading the vessels. Motors can also wear out and bearings or gear boxes can become dry, causing slower rotation speeds. If the tumbler was purchased, check with the manufacturer's documentation for proper operation and maintenance.

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