Are you using straight co2 or are you injecting a cosolvent as well? If a cosolvent, target collecting that in the first separator, in which case the first separator should be nearly at the extraction vessel pressure and temp, just providing a reservoir for the cosolvent to collect via gravity.
Generally speaking, it wi take many r and d runs to fine tune your rig.
From upstream to downstream your separators should step down from high to low pressure, for efficiency’s sake. Temperature should be adjusted based on what you’re trying to condense in that particular separator. Hint: use the compounds collected in the next downstream separator as a limit for the temperature setting.
For example, compound A drops out at P1 T1, Compound B drops out at P1 T1-20*.
Set the temp in separator A at T1-15* or T1-10* so and the temp in separator B at T1-40*. This will help with fully condensing A in one collector and condensing B in another while minimizing overlap.
People keep their separator settings pretty close to their chest, but there’s a lot of scientific data about the solubility of certain compounds or groups of compounds for extraction at certain pressure/temp combinations. Working from High P to Low P, stack them in order and that should give you reasonable starting points.
Its helpful to work backwards from the downstream most point of your system (last separator or vent) at room temp ambient pressure. Temp in the last separator should be above the condensing temp for co2 so that clean co2 gas exits the vent port and will keep liquid co2 out of the separator. Adjust the settings on the separator just upstream until you find a desired breakpoint, then move to the next upstream separator and repeat. Once you’ve mapped out the breakpoints, between ambient conditions and your operating conditions, from those breakpoints choose strategic ones to group certain compounds together based on the amount of separators you have.
A lot of times i see videos emptying collectors mid run with a valve open to ambient pressure. Opening that valve to empty the collection vessel usually lets all the pressure out of that cv as well, at which point all the suspended compounds condense, negating any fractionation effort. Rather than using a valve, get larger collection vessels and empty between runs.