Application for Rheotherm and RheoVac Instruments
MaxExtractor Extraction Monitor

MaxExtractor Extraction Monitor

The Rheotherm MaxExtractor Extraction Monitor is a ground-breaking innovation from Intek, your process flow partner. The unique capabilities of this instrument enable you to get the most from your botanical oil extraction process.

Rheotherm MaxExtractorThe Rheotherm MaxExtractor is a thermal properties sensor which tracks the changes in the properties of the extract fluid as the extraction progresses from pure solvent to a solvent with oil extract. Using the MaxExtractor allows you to track the rate of extraction of oil from the source material and determine when the extraction process is complete. The MaxExtractor Extraction Monitor gives you the information needed to fine tune your process and increase your efficiency. Save time. Save money. Improve product throughput.

What Can We Measure?
The Intek Rheotherm MaxExtractor Extraction Monitor can be used to monitor the extraction of oils from botanicals using any of these common extraction techniques:

Using high-proof alcohols as the solvent for extracting the soluble components of plants is very popular in the essential oils and botanicals industries. Accurate measurement of the amount of solvent used and recovered in the process, as well as the amount of oil vs. ethanol in the extract is provided by the Rheotherm MaxExtractor Extraction Monitor.

Another common extraction method to separate desirable materials out of plant materials uses hydrocarbons such as butane and propane in their liquid state as the solvent. The extraction process produces an oil which contains the desired end products from the plant combined with the butane/propane. The butane/propane is removed through purging which can result in the release of highly flammable off gasses leaving the pure oil extract. The Intek MaxExtractor Extraction Monitor is available in explosion-proof configurations making it the ideal solution for these measurements.

Supercritical CO2
Supercritical carbon dioxide extraction is a commonly used method because it produces a pure, clean, and safe end product because no residual solvent is present in the end product. This process can be difficult to control due to the inherent fluctuations in pressure and temperature which makes it critical to be able to accurately measure the CO2 and other solvent which may be used in the extraction. Providing accurate measurement in high-pressure CO2 extractions can be tough with any sensor, but the Rheotherm MaxExtractor is able to compensate for these pressure and temperature variations and it can operate at pressures of 6000 PSI and greater if needed.

Contact us using the form on this page or any of the ways shown on our Contact Us page to discuss how we can help you optimize your extraction application.

How does it Work?
The Rheotherm MaxExtractor Extraction Monitor is a thermal properties sensor which detects the change in viscosity, thermal conductivity, and heat capacity as the fluid transitions from pure solvent to solvent with oil extract. The output of the instrument is a combination of these three thermal properties. This chart shows the output of the MaxExtractor Extraction Monitor (‘TPS Indication’ in the chart). MaxExtractor OutputThe percent of oil indicated in the extract increases as the process begins and increases steadily until it levels off and eventually starts to decrease to the base level. When this value is tracked over time, it gives you important information about the rate of extraction, the magnitude of oil extracted and when your extraction is complete so that you can MAXimize the extraction of oil from your source material in the optimal processing time.

Many liquid-based extractions use a recirculating type process where an extractor is filled with biomass and solvent, the solvent is drained out from the bottom and pumped back over the top. In these extraction setups, the MaxExtractor is installed in the recirculating line to determine the concentration of end product oil in the flow stream out of the extractor.

Other extractions use a washing or centrifuge type process where the extractor is filled with biomass and solvent and the biomass is spun or agitated in the solvent pool. In these cases the MaxExtractor is located in a small bypass line where a small amount of fluid is continuously sampled and pushed with a micro gear pump through the sensor to determine the oil concentration. This same setup can be used for recirculating processes if the recirculation pump does not have a steady flow rate.

Most supercritical CO2 extractions use a once-through operating principle, where fresh solvent is pushed through the extractor until all oil is extracted. The Rheotherm MaxExtractor can improve the efficiency of these operations by detecting the rate of oil extraction. In these systems, two MaxExtractor Extraction Monitors are used, one before and one after the extractor. The output of the two sensors are compared and the difference between them is proportional to the instantaneous concentration of extracted oil.

How Are They Installed?
The Rheotherm MaxExtractor Extraction Monitor incorporates an in-line Rheotherm flow sensor that is typically installed with plain tube-end fittings suitable for compression fittings, but is optionally available with other fittings as required by the application. Contact us to discuss your specific process requirements.

How Do I Get One?
Contact one of our extraction application specialists using the form on this page to configure an instrument tailored to your needs. You can also visit our Contact Us page for telephone, fax and email information.

  • Output of solvent vs. extract concentration
  • Advanced temperature compensation
  • Measurement of liquids or gases
  • Exclusive inline TU sensor
  • Advanced signal processing electronics
  • Easy installation
  • Long-term reliability


Temperature Process: 0 – 120°F (-18 – 50°C)
Environment: 0 – 120°F (-18 – 50°C)
Pressure 0 – 500 PSI
Calibration Ranges 10:1 Turndown (standard)
Up to 100:1 Turndown available
Liquids: 0.05 cc/min to 2 LPM
Gases: 0.0017 to 3 SCFM
Calibration Accuracy  ± 1% of reading typical
Response Time  1 sec. ; 3 – 5 sec. typ.
(63% of range)
Repeatability ± 0.5% of reading
Line Sizes
(flow range dependent)
1/16”; 1/8”; 3/16”; 1/4”
Process Connection Plain tube stubs suitable for compression fittings
Wetted Material 316 SS
Display 2-line OLED display of:
– Mass/volume flow rate
– Setpoint
Enclosure Sensor: PVC
Integrated Electronics:  NEMA 4X Cast Aluminum
Flow Output 4 – 20 mA (standard); 0 – 10 or 0 – 5 VDC (optional)
Input Power 24 VDC ±4V @325 mA (max)
pdf (1) Product Summary (TBD)
pdf (1) User Manual (TBD)
word Rheotherm Flow Application Data Sheet (download document)
pdf (1) Rheotherm Method of Operation
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