I am not aware of any alternative. That flow tube is a 2% accuracy precision flow measuring device. It should not ever break unless something hits it! If it is installed incorrectly it could break....there is a small plastic x piece that is supposed to be installed in the top of the tube....this is a cushion that keeps the tungsten float ball from slamming the glass tube under high gas pressure conditions. I would suggest you contact Hypertherm's tech service to resolve the breakage issue.
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Best regards, Jim Colt