Below you will find frequently asked questions about our devices, clearly structured according to product categories.


Hei-VAP Rotary Evaporators

Can the Hei-VAP Benchtop rotary evaporator be flooded with inertgas?

Yes, the rotary evaporator can be flooded with inertgas via the ventilation valve of the vacuum box. In addition, a
external pressure reducer is required to not exceed 0.2 bar overpressure (overpressure shutdown of Hei-VAP Precision).



Can a spider with ground joint 24/29 be attached to a Hei-VAP with ground joint 24/40?

A  spider NS 24/29 can be used on an evaporator with NS 24/40. There is no adapter or other accessories needed.

Show all Hei-VAP accessories



How is the tightness test of the cooling circuit of a Hei-VAP performed?

To check the tightness of the cooling circuit, please proceed as follows:

The test must be carried out with a dry system to exclude that the drops on the cooling coil are distillate. If the system is completely dry (no residues of water or solvents), evacuate the system and run the chiller at the same time.

Then observe the leak rate or increase in pressure and check whether coolant enters the evaporation chamber.



Hei-VAP Industrial Large-Scale Evaporators

Which vacuum pump can be used with a Hei-VAP Industrial?

For use on a Hei-VAP Industrial large-scale evaporator, the vacuum pump Rotavac 20 (with condensate cooler and aspirator) is suitable.

Go to Rotavac 20



Hei-PLATE Magnetic Stirrer

Do Heat-On and bath attachments also fit on other magnetic stirrers and can these attachments slip?

The Heat-On addons and bath attachments fit on all Heidolph Hei-PLATE magnetic stirrers with heating function.
All Heat-On addons have a fixing edge, which means that they are accurately centered on plates and can no longer slip.

Show all Heat-On addons



Is it possible to operate the MR Hei-Standard together with the Pt 1000 temperature sensor?

It is possible technically, because as soon as the sensor is connected it regulates the temperature. However, there is no digital display to set the exact temperature, since the device has only analog scaling available.

Go to Pt 1000



Are there magnetic stirrers without heating function available?

Yes, the magnetic stirrers Hei-Mix S and Hei-Mix L have no heating function.

For larger quantities we recommend alternatively the magnetic stirrer Hei-Standard, which can be operated without the heating function.

Show all magnetic stirrers



Hei-TORQUE Overhead Stirrer

What material is the Quick-Chuck quick-action chuck housing made of?

The Quick-Chuck is made of polyamide (PA) and thermally stable up to 115 ° C.



What is the tightening torque of the Quick-Chuck quick action chuck on the Hei-TORQUE models?

The tightening torque of the quick release chuck is individually adjustable. By the good audible clicks when tightening the Quick-Chuck, you can easily estimate the tightening torque:

1. First resistor    = Minimum 1.1Nm, ø 2.5Nm
2. First click         = Minimum 3.1Nm, ø 3.1Nm
3. Second click    = Minimum 4.3Nm, ø 7.7Nm
4. Third click        = Minimum 5.0Nm, ø 10.1Nm
5. Fourth click      = Minimum 9.5Nm, ø 14.5Nm



What do the additional numbering at the end mean (100, 200, 400)?

The numbering on the Hei-TORQUE models describes the respective torque of the overhead stirrer. For example:

Hei-TORQUE Value 100 = Overhead stirrers with 100 Ncm torque
Hei-TORQUE Value 200 = Overhead stirrers with 200 Ncm torque
Hei-TORQUE Value 400 = Overhead stirrers with 400 Ncm torque

Got to the Hei-TORQUE series



Which replacement devices are there for the RZR series?

The technical data do not match exactly due to the various developments in the meantime. Nevertheless, comparable devices are staggered as follows:

RZR 2020                 Hei-TORQUE Value 100
RZR 2021                 Hei-TORQUE Value 200
RZR 2041                 Hei-TORQUE Value 400
RZR 2051 control     Hei-TORQUE Precision 100
RZR 2052 control     Hei-TORQUE Precision 200
RZR 2102 control     Hei-TORQUE Precision 400



What does the torque indicator on the Hei-TORQUE models say?

The Hei-TORQUE Value models shows bars on the display, indicating changes in the torque or viscosity of the fluid.

The Hei-TORQUE Precision models show the actual torque in Ncm with one decimal place.



Hei-MIX Shakers & Mixers

Is the attachment for the Multi Reax sold separately?

Yes, the attachments can be purchased separately:

12 vessel attachment P/N 036303540 (US)  /  549-03000-00 (worldwide)
26 vessel attachment P/N 036303530 (US)  /  549-01600-00 (worldwide)

Send us your requesrt, if you are interessted in Hei-MIX addons or attachments. We will take care of your needs:

Contact form



Which bottle sizes can be used in the Reax 20?

The recommended maximum height of the vessels is 270 mm, with a maximum diameter of 136 mm.

Through various adapters, a variety of different bottle sizes can be mounted in the Reax 20. Without adapter, you can process vessels with 55 mm diameter and a height of 250 - 270 mm.

With the help of the adapters, the following possible bottle heights result:

Height:                              Attachements:

248 – 208 mm  =  1x Attachement for 1l bottles
206 – 166 mm  =  2x Attachement for 1l bottles                                  
202 – 162 mm  =  1x Attachement for 0.5l bottles
160 – 120 mm  =  1x Attachement for 1l bottles & 1x Attachement for 0.5l bottles
114 –   74 mm  =  2x Attachement for 0.5l bottles
72 –   32 mm    =  1x Attachement for 1l bottles &  2x Attachement for 0.5l bottles



Hei-FLOW Peristaltic Pumps

How to prevent bubble formation in the tube?

When used correctly, no air bubbles emerge in the tube. The end of the tube must be deep enough in the container, from which the substance should be pumped.



What is the minimum flow rate for the Hei-FLOW peristaltic pumps?

With our Hei-FLOW peristaltic pumps, the high precision achieves minimum flow rate of only 0.005 ml/min.



Your question is missing?

If you cannot answer your question with the help of our database or if you prefer the personal contact, please send us your request via the online contact form or call us: +1 224-265-9600