Frozen fingertight fittings

[seravitae]

Hello,

I've noticed that the fingertight fittings we use for low pressure inlet to pump (1/8") become swollen or sheared, and freeze up. On several occasions we've had to attempt to unscrew them using a wrench for leverage, but this results in the head snapping off, and then our workshop must bore out the tubing and remaining ferrule/fitting pieces from the check valve head.

We only run pure methanol and milli-q (no salts or buffers) through our system.. Is this is a common thing to occur? I thought the fittings were solvent resistant, especially to fairly nonreactive solvents like water and methanol.

Has anyone experienced this, or are we doing something wrong, or is our storage protocol (leaving solvent in the lines) incorrect?

Cheers,
Seb

[tom jupille]

They may have been overtightened to begin with, but I suspect anything made of plastic will become brittle given enough time.

our workshop must bore out the tubing and remaining ferrule/fitting pieces from the check valve head.

Take a small screwdriver and rest the blade on a hot plate for a minute or so and then jam it into the broken fitting. Wait a moment for the melted peek to cool and then simply unscrew the stub of the fitting.

[MaryCarson]

Take a small screwdriver and rest the blade on a hot plate for a minute or so and then jam it into the broken fitting. Wait a moment for the melted peek to cool and then simply unscrew the stub of the fitting.

Thanks, Tom! Little knowledge nuggets like this are one of the reasons I love this forum.