We recommend:

• 591-35000-00MPE: Tube Set for Hei-VAP 12m

This contains 12 m of tubing suitable for connecting your Hei-Vap to both a vacuum pump as well as to a water source or recirculating chiller. The tubing is transparent, FDA-approved and UV-resistant. If you would like to supply your own tubing, the specification for both the water and vacuum connections on a Hei-Vap is 8 mm internal diameter.

A manual vacuum controller (part number 591-26000-00) is an optional accessory for either of the following Heidolph rotary evaporators:

• Hei-VAP Core
• Hei-VAP Expert
• Hei-VAP Ultimate

when used with one of the following vacuum sources:

• valve-regulated vacuum pump (not a Vario pump)
• house vacuum

With these equipment combinations, the manual vacuum controller is recommended, as it is a low cost, simple way to enable you to monitor and control the vacuum level. You view the dial and open the valve to bleed air into the system to adjust the vacuum. Vacuum control is desirable so that the vacuum level is suitable for evaporating the solvent in question and to act against bumping/foaming or overloading the condenser. For digital vacuum control of house vacuum systems or valve regulated vacuum pumps, the Hei-VAC vacuum controller is available.

It comes complete with an integrated ceramic vacuum sensor, regulation valve and venting valve. It can be fixed on the condenser shaft above the evaporator or used as stand-alone device with base next to the unit. It is compatible with the same Heidolph rotary evaporators as the manual vacuum controller as well as any other brand of rotary evaporator. For optimal vacuum control, a Heidolph rotary evaporator with integrated vacuum control in combination with a Heidolph Vario vacuum pump is recommended. In this case you wouldn’t need an additional vacuum controller as the vacuum is set using the control panel of the Hei-VAP.

A vacuum valve (part number 569-00065-00) is a required accessory for the Heidolph Hei-VAP Expert Control and Ultimate Control when used with one of the following vacuum sources:

• valve-regulated vacuum pump (not a Heidolph Vario pump)
• house vacuum

The Hei-VAP Expert Control and Ultimate Control contain an integrated vacuum controller (the ‘brains’), but you need to purchase the vacuum valve if you are not using a Heidolph Vario pump, as the valve is what opens and closes in order to regulate the vacuum. For optimal vacuum control, a Heidolph Vario vacuum pump is recommended instead:

• Hei-VAC (Rotavac) Vario Tec (12 mbar)
• Hei-VAC (Rotavac) Vario Control (2 mbar)

In this case you wouldn’t need the vacuum valve as the Hei-VAP communicates with the pump to adjust its speed and regulate the vacuum.

You can choose between valve-regulated and Vario (also known as RPM or speed regulated) vacuum pumps for a rotary evaporator (depending on the rotary evaporator configuration you choose). Valve regulated pumps control the vacuum by opening and closing a valve. The vacuum pump runs at full power at all times; when the vacuum reaches a specific level, the valve is triggered, which opens and releases some of the vacuum.  This is a simple, low cost option. Vario vacuum pumps can alter their pumping speed (rpm), offering more precise control of the vacuum and lets the user set their required vacuum level. The advantages of Vario pumps over valve-regulated ones include:

• Increased energy efficiency
• Increased solvent recovery rate
• Reduced bumping/foaming
• Reduced noise and vibration
• Reduced wear on the pump – increased lifetime

The AUTOaccurate is an advanced program available with the Hei-VAP Expert Control and Ultimate Control rotary evaporators (not Hei-VAP Core, Expert or Ultimate). The AUTOaccurate function allows for automatic adjustment of the vacuum level based on the temperature increase detected at the condenser by the AUTOAccurate sensor. It then holds the vacuum level at this point until the temperature increase is no longer detected. It can also identify multiple boiling points – multiple solvent distillation is possible without any manual adjustments. The AUTOaccurate temperature sensor (part number 569-00040-00) is required for this program. This temperature sensor is only compatible with the G3 and G3 XL (vertical condensers) and G6 (vertical condenser with valve for reflux distillation) glassware sets. This means the AUTOaccurate program cannot be used with the G1 (diagonal condenser) or G5 (dry ice condenser) glassware sets.

It depends on how you are intending to use vacuum.

Subjecting the whole Findenser unit to vacuum (e.g. placing it in a vacuum drying oven)

You should not do this – it could damage the Findenser seals.

Pulling a vacuum through the inner glass body of the Findenser before use

You can do this, for instance to dry the inside of the Findenser, or to remove air to replace with inert gas before an experiment. As the inner glass body is an open tube, the vacuum level achieved would depend on how you had it connected up (e.g. whether you made a good seal at each end, and which vacuum pump you used).

Pulling a vacuum through the inner glass body of the Findenser during use; use as a rotary evaporator condenser

This is not recommended. In rotary evaporators, vacuum is used to reduce the boiling point of the solvent, e.g. to 40°C. This would therefore reduce the temperature difference (delta T) between the chemical vapour temperature and ambient (air) temperature – and a good delta T is required for heat to effectively be dissipated out from Findenser.  Findenser would therefore not perform well, so is not suitable for this type of application. Furthermore, if you ran an experiment while you drew a vacuum up through the Findenser and out of the top, you would be pulling the generated chemical vapours up more quickly through the Findenser, reducing its performance; and if you connected the vacuum to a side arm, the chemical vapours would be drawn directly out the side arm, bypassing the Findenser.

Use of Findenser on the exhaust of a vacuum pump (e.g. of a rotary evaporator)

Findenser works well as a vacuum pump exhaust condenser – see our case study.