FAQs - FlowSyn operation and maintenance
Contents:
What is the maximum usable pressure of the standard FlowSyn?
What is the maximum temperature the standard Uniqsis FlowSyn can reach?
Can I rewind my FlowSyn coil reactor?
Can I pump organometallic bases such as LiHMDS and BuLi using FlowSyn?
Is it always necessary to store the FlowSyn in iPrOH after use?
What about changing between immiscible solvents?

What is the maximum usable pressure of the standard FlowSyn?
All new standard FlowSyn units are rated to 1000psi (or 70bar). However this maximum is only possible when using Stainless Steel or Hastelloy® coil reactors. When using Teflon or PFA coil reactors the pressure is automatically limited to 200psi (or 14bar) for safety.

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What is the maximum temperature the standard Uniqsis FlowSyn can reach?
The standard FlowSyn includes two separate heating modules. The coil reactor unit (homogeneous) can be heated to 260°C and the column reactor unit (heterogeneous) can be heated to 150°C. The temperature of each reactor has been calibrated so that the temperature of the solution is accurate to ±1°C. The maximum temperatures are achievable using the stainless steel coil reactor (260°C). For Teflon and PFA coil reactors the system limits the maximum temperature to 150°C.This ensures that the tubing is not damaged by over-heating.

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Can I rewind my FlowSyn coil reactor?
Yes. The coil reactors have been made so that the tubing can be quickly and easily replaced by the user in the event of blockages or material fatigue. PTFE tubing should be replaced periodically to reduce the risk of potential rupture (- after every 10 - 20 uses is recommended, particularly as repeated pressure and heat cycling of thermoplastic materials causes fatigue), so we have made it as easy as possible for you to re-wind your own. We can provide tubing in bulk quantities to help reduce the cost. We are also more than happy to re-wind your coil reactors for you, but this is only really worth considering where the coils are made of metal (stainless steel or Hastelloy®).

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Can I pump organometallic bases such as LiHMDS and BuLi using FlowSyn?
Yes. However, we recommend that you adhere to the following guidelines:

• The organometallic should not contain precipitate. If so, it is advisable to use an in-line filter.
• All solvents should be anhydrous, and the stock bottles inserted under a N2 or Ar blanket (tubing from a low pressure gas manifold can be terminated with the ends of disposable syringes and these can be inserted directly into our recommended bottle tops). A short length of wide-bore SS tubing can be inserted directly through Sure-Seals and connected directly to the FlowSyn using standard fittings.
• The flow path should be thoroughly flushed through with an anhydrous solvent (e.g. THF) before any moisture sensitive or air sensitive reagents are pumped.
• We recommend that you fit a Backflush Kit (UQ-7210) to the pump heads. Salts (amongst other things!) derived from hydrolysis of organometallic reagents tend to accumulate between the high and low pressure pump seals. These should be removed periodically by either dissembling the two halves of the pump heads, or more conveniently, by flushing with a suitable cleaning solvent using the Backflush Kit (e.g. 1:1:1 [AcOH:THF:H2O] or [AcOH:THF:DMF]).
• The FlowSyn should be flushed with a cleaning solvent after use (1:1:1 [AcOH:THF:H2O] works well), and then stored in iPrOH.

This protocol should ensure that your FlowSyn performs reliably.

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Is it always necessary to store the FlowSyn in iPrOH after use?
It is very important, particularly if you pump reagent solutions through the pump heads, to clean them out thoroughly after use and then store them in a benign solvent. iPrOH is particularly good because it helps to ensure that the check valves in the pump heads are conditioned properly. Other clean solvents are also suitable overnight, however, we recommend iPrOH for prolonged storage of the FlowSyn.

If you are using a fluorous system solvent (for plug flow work), we recommend that you do not routinely switch back to IPrOH to store the system in overnight. Leave it primed with the fluorous solvent. Conditioning the check valves to give stable flow can be particularly problematic and require prolonged flushing in these cases.

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What about changing between immiscible solvents?
If you wish to pump a solvent that is not miscible with the solvent that is currently in the pump head(s), then it is very important to first thoroughly flush the pump heads with a solvent which is fully miscible with both solvents. This will ensure that the check valves are properly conditioned and that the pumps will give a stable flow. A good example is when switching between water and toluene. DMF is a good choice of intermediate flush solvent in this case.

Fluorous solvents pose a particular problem. However, MeOH can be effective in these cases.

However, if you subsequently intend to pump a solvent that is not miscible with iPrOH then you should ensure that any residual iPrOH is thoroughly washed out of the pump heads and check valves using a solvent that is miscible with both solvents. This applies whenever you wish to change between immiscible solvents. Always flush thoroughly with a solvent that has miscibility with both solvents.

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