april 7th meeting

[pipettemonkey]

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Yeah I know of the hate the Chinese have for the Japanese. I've seen many jokes on line done through Flash about the Japanese. I know of what the Japanese did in WW2. It was horrible. Infact the
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 Condoms are usually easy to get. teach you h ow to m ake the health iest carbohy drate choices, which will allow yo u to stimulant hormone, and a reduction

[WK]

Hi pipettemonkey,

I had one of these 10years ago.
From memory there is a porous white frit and "gold" seal/cap inside the
purge valve. I replaced these parts frquently (the white frit becomes discoloured and the "gold" seal dented). Have you replaced these recently?
Also I remember having to replace the purge valve itself once in the instrument's lifetime (for whatever reason - I don't remember).

In the photo, by purge valve I refer to the "tower" on the top RHS of pump block - from which the clear waste pipe (left) and blue inlet line (right) feed from and which includes the knob.

Regards

WK

[HPLCCONSULT]

The valve you speak of is actually a needle valve, not a ball valve. It is a very precise instrument and can be clogged or damaged from abuse. Based on your description of the valve NOT showing close to atmospheric pressure when open there are two possible reasons for this:

(1) You have installed or reassembled the purge valve incorrectly. I have never seen anyone do this before, but it is possible something is blocking the opening in the pump outlet to the purge valve (debris of some kind or the gold seal has been moved out of position and is now sealing the opening).
(2) The PTFE frit is clogged with debris. As 'WK' mentioned, the PTFE frits are pre-filter which are designed to be replaced every month or so as they collect all of the large particular matter from your solvents (that gets through) and the normal bits of pump seal material that make their way through the system. The frits job is to stop these materials from making their way to your A/S and column and they do a great job. A normal frit will appear snow white in color, but may have a few fleks of black (pump seal debris). These are a standard maintenance parts and should be replaced often as they protect your entire system (We teach our clients to do this every month. The frits are very inexpensive and you should wash the valve out each time as well before placing the new frit back in). The frit is held inside the valve through the use of a plastic cap and gold seal gasket. The gold seal should last the lifetime of the system. The plastic cap can sometimes be damaged by someone tighening the valve too much or not seating it correctly on the valve. Otherwise, it too should last the lifetime of the instrument.

Bottom line is that you have an obstruction in the purge flow path. I would remove the purge valve; inspect/clean out the inside of the pump head where the purge valve screws into; remove the plastic cap, gold seal and PTFE frit from the valve; open the valve; hold it inside of a ~600 ml beaker; using a wash bottle filled with solvent (e.g. MeOH) spray liquid into the valve's solvent outlet (to the column) opening until you see it shoot out the bottom of the valve (needle portion). It will also come out the purge opening as well (normal). This will clean and wash the valve. If resistance is encountered, then you may have damaged the valve in which case replacement is suggested. Always use new PTFE frits and have plenty on hand for regular maintenance each month.

[Jackus]

Everything was told before. Last thing to check is if there is not blockage of PTFE tubing. Once I saw that whole instrument was standing on it.

[Consumer Products Guy]

The 1050 purge valve is the same as on the newer 1100 models. The PTFE frit gets clogged frequently (doing its job); the way to check is that an aqueous solution pumping out through the open purge valve at 5 ml/min should be less than 10 bar.

We've replaced two purge valve this year due to leakage out the waste line when closed, most years none go bad (about 10 units). Not a big deal, sometimes hard to diagnose because the waste line usually has tubing connected to it, making it un-obvious.

[HPLCCONSULT]

"Consumer Products Guy"; If you have replaced a purge valve due to leakage out the waste line this was because someone overtightened the valve closed. These are very precise valves and only require a gentle turn of the valve knob to seal 100%. When people "crank" down on them thinking that tighter is better, then the seal is destroyed and the valve will leak. We have seen dozens of prime purge valves that have tool marks on the knob from someone using a pair of pliers to open them back up due to someone overtightening them.

To open the valve simply turn it one or two turns max (that is all that is needed). Do not spin it several 360 degree rotations. To close it just gently turn it till you feel some resistance and it should be sealed (you can remove the waste tubing to double check that fluid is not coming out when the pump is running).

[Consumer Products Guy]

"Consumer Products Guy"; If you have replaced a purge valve due to leakage out the waste line this was because someone overtightened the valve closed.

This is possible, there are multiple users. But maybe four replacements in 20 years with multiple systems doesn't make it a big deal.

We have seen dozens of prime purge valves that have tool marks on the knob from someone using a pair of pliers to open them back up due to someone overtightening them.

We've never had to use a tool of any kind to open one.