pulse dampener

[evo]

Hello,

I have a question about a pulse dampener. I'am using a waters 2695 HPLC semi-automat with a ECD detector.
If I connect the pulse dampener between the tubing-out from the 2695 and the colomn I use, the noise becomes worse instead of less. the Flat-line pulse dampener (Restek) is placed into the housing of the ECD-detector.

What is the right place in such a configuration?

SC
Evo

[Gerhard Kratz]

The Alliance System normally don't need a pulse damper. The right place to install is between the pump out and the injection valve or autosampler. Remember that the volume inside the pulse damper is very large. Maybe you need to purge your pulse damper with your mobile phase more. Do you use elevated temperature or a column thermostate? Please make sure that all parts of your system have the same temperature.

[evo]

The Alliance System normally don't need a pulse damper. The right place to install is between the pump out and the injection valve or autosampler. Remember that the volume inside the pulse damper is very large. Maybe you need to purge your pulse damper with your mobile phase more. Do you use elevated temperature or a column thermostate? Please make sure that all parts of your system have the same temperature.

Ok that's clear. Thank you for your answer.
Then I have to placed the pulsedampener inside the Alliance just behind the in-line filter which is situated just behind the tubing which comes out of the pump. The internal volume of this pulse dampener is 600–700 μL , so that's not the problem I suppose. Temperature is not really critical. So it should be just the place of the thing. Before the injector and not behind.
Could you explain to me, just curious, why the place of the pulse dampener is so important.

[tom jupille]

It's kind of like a shock absorber. It sould be upstream of the first significant flow restriction in the system (because that's where there's the most pulsation).

[evo]

It's kind of like a shock absorber. It sould be upstream of the first significant flow restriction in the system (because that's where there's the most pulsation).

I see, that's logical. Thank you for the answer.

Evo

[swensen]

Many mobile phase pumps do not produce perfect pressurized streams (piston pumps have to retract the piston and this causes short fluctuations) and as Tom said, pulse dampeners help smooth the stream/pressure. Locate the pulse dampener immediately down stream of the pumps and upstream of anything else including mixers and injectors. Periodically check the dampener for leakage (diaphragm type dampeners sometimes have a color dye methanol mix on one side of the dampener diaphragm as a 'tell' for leakage).