does permanent flow in the LC protect the pump seals?

[RALS]

They told me that a permanent low flow in the LC make the seals last longer. does anybody had the same experience?
cheers

[tom jupille]

Yes, particularly if you have buffers in your mobile phases. The rationale is that the thin film of liquid on which the lip of the seal skates can evaporate and leave behind abrasive buffer crystals under no-flow conditions. Maintaining a low flow when the system is idle keeps everything moist and happy, and is easier than flushing the system with buffer-free mobile phase.

[Gerhard Kratz]

I agree with Tom 100%. But please don't use a solvent recycler. Ups, now a nice discussion is started.............

[RALS]

Thanks for your reply. I will do so and no ... no solvent recycler
cheers

[greenlab]

Hello RALS,

You can use the mobile phase recycler without any problem. See the forum discussion titled "Mobile Phase Recycler" where you will find good discussion about this topic.

viewtopic.php?f=1&t=9449&p=74418&hilit= ... rak#p74418

Regards;
greenlab

[lmh]

Surely this depends enormously on the lab and the workflow.

My lab, for example, is using low-stress, easy solvents (acetonitrile versus water/formic/acetic acid mixes - everything is volatile), and has most instruments on some sort of service regime meaning that there will be new seals each year. Under these conditions we don't get seal failures. We do turn pumps off between sample batches. Some instruments are being used very occasionally, but most (the modern ones) somewhere between 2000 and 3000 hours per year.

If you are using an instrument very rarely, I'd say flush with a safe solvent and turn the pump off. Otherwise you will save yourself 100 units of cash on pump-seals by spending 400 units on solvents.

If you are using an instrument almost continuously, then it doesn't matter what you do - both options tend to become identical as usage tends to 100%!

If you are using an instrument somewhere between the two, it's a cost-benefit study that depends on how cheaply you source your solvents, how nasty they are for the pump, and how regularly you change seals anyway (if you successfully increase your seal life from 14 months to 19 months, but in any case change them routinely at 12 months, you have saved absolutely nothing!).