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Wanted some help with flare line sample collection methods

Wanted some help with flare line sample collection methods

Wanted some help with flare line sample collection methods

I've been asked by a client to provide a sample collection arrangement on a flare line. How do I decide which is the best possible method for sample collection ?
The method should be a spot sampling method & not a continuous one. The contents of the flare are mainly gaseous hydrocarbons. Also the collected sample can be in either gaseous form, or it could also be condensed to liquid form.
I came across 2 main methods - (1) Collect sample using a hand drawn pump, (2) Collect it in a sampling cylinder using control valves.
How do I decide which one to choose ? Also for both methods, there are multiple types of pumps available commercially, so how do I choose which vendor to buy from as well ?
Thanks !

RE: Wanted some help with flare line sample collection methods

My experience was that the gas sampling system may include a purge system (either N2 or NG) and a sampling circulation stream. The purge system is to clean up the piping before and after taking the gas sample. The circulation stream is to make sure the flare gas kept in the closed loop.

RE: Wanted some help with flare line sample collection methods

Since the contents of the flare are mainly HC in gaseous form. I would pick the method of a gas cylinder as you will most likely send to it to a lab equipped with Gas Chromatography (GC). Moreover, depends on the height of the flare, the upstream pressure should be considered as well.

RE: Wanted some help with flare line sample collection methods

How often are they going to sample? Daily? Monthly?
If it is monthly go with a simple purge and sample bottle arrangement.
If they are going to sample frequently and there is positive pressure to work with then you likely would want a sample line with some continuous small flow.
That way whenever they took a sample it would be representative of what is currently in the flare line.

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P.E. Metallurgy, Plymouth Tube

RE: Wanted some help with flare line sample collection methods

If your flare header pressure is too low to allow a flow-purge through the collection system, collecting the gas sample may require the use of a Haskel compressor ( instrument air pneumatic driver) or similar. You will have to vent this purge stream safely during the collection operation. Typically these sampling operations are carried out under PtW ( permit to work) authorised by the operations shift leader, subject to approval of the sampling operations procedure.

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