DiFluid RS Extract User Manual
October 2026, V1.0
Precautions
!If the device reaches about 70 °C (±5 °C) during shipping or storage, high-temperature protection is triggered. If the device does not turn on, charge it and try again.
!Do not insert anything into the pressure relief hole. It can damage the device.
!RS Extract is designed to measure coffee only. Measuring other liquids is not supported and may affect performance or damage the device.
Watch Video Tutorials
For the latest specifications and details, refer to the latest electronic version of this manual.
Click the link or scan the QR code to watch video tutorials and read the latest manual, so you can use this product correctly and safely.
User manuals: https://digitizefluid.com/pages/documents
Read this manual carefully so you can use this product correctly and safely.
- Thank you for purchasing DiFluid RS Extract Professional Coffee Refractometer.
- The information and specifications in this manual may change without notice as the product is improved.
- Every effort was made to make this manual accurate at the time of writing. If you find an error, please let us know.
!Do not open the casing unless you are a qualified service technician. Doing so voids the warranty and may damage the device or stop it working.
!DiFluid is not responsible for any damage caused by using this product (including accessories) in a way other than described in this manual.
!DiFluid is not liable for any direct, indirect or special damages caused by a defect in this product, even if advised of the possibility of such damages, nor for any claims by third parties.
!If the device behaves abnormally, contact customer service at the store where you bought it.
Product Introduction
RS Extract is a professional, high-precision coffee refractometer for measuring TDS. It measures the TDS of coffee quickly and accurately, so baristas can put a number on extraction and use data to improve their brew recipes. It suits specialty coffee shops, coffee training, roasting labs and home brewers.
Measured feedback helps you refine your brew recipes.
Brew and extract with data, not guesswork.
Stable Readings with Less Environmental Interference
High-stability optical refraction with temperature compensation keeps readings reliable in different environments. IP67 water resistance stands up to heavy daily use on the bar and in the coffee lab.
USB-C Charging and a Long-Lasting Battery
A built-in 3000 mAh battery, charged over USB-C. Light and portable, so it is easy to use on the bar, in training rooms and when measuring away from your shop.
Built for Professional Coffee Extraction
RS Extract is more than a refractometer. It helps baristas build a consistent extraction routine. Recording and analyzing TDS moves coffee making from judgment by experience to decisions based on data, steadily improving quality and consistency.
Product Overview
Package Contents
①QR code card
②Quick start guide
③Product information card
④Coffee spoon
⑤Magnetic lid
⑥Charging cable
Specifications
| Specification | Value |
|---|---|
| Product Name | RS Extract |
| Model | DFT-RS01 |
| Dimensions (L × W × H) | 150 × 72 × 28 mm |
| Measurement Range | 0–30% TDS |
| Precision | ±0.02% TDS |
| Accuracy | 0.00–4.99%: ±0.02% TDS 5.00–20.00%: ±0.04% TDS 20.01–30.00%: ±0.06% TDS |
| Resolution | 0.01% TDS |
| Refractive Index Range | 1.33299–1.38660 |
| Refractive Index Precision | ±0.00004 |
| Refractive Index Resolution | 0.00002 |
| Measurement Time | <4 s (typical; hot or iced coffee takes longer) |
| Operating Temperature | 5–45 °C |
| Sample Temperature Range | 4–65 °C |
| Battery Capacity | 3000 mAh |
| Charging Port | USB-C |
| Charging Time | about 4 hours to full |
| Charging Input | 5 V / 0.8 A |
| Battery | Non-removable |
| Water Resistance | IP67 |
| Record Storage | Up to 500 records. Once full, the oldest record is deleted automatically. |
About the Power Supply
This product uses a lithium-ion battery.
Lithium-Ion Battery Precautions
For your safety, follow these precautions when handling the battery:
!If you will not use the device for a long time, charge it fully before storing it and recharge it regularly. Storing it with a low battery can damage the hardware and cause it to fail.
!Do not disassemble or modify the battery. The battery has built-in safety mechanisms and protection circuits. If these are damaged, the battery may overheat, smoke, burst or catch fire.
!Do not charge near open flames or in hot places, such as in direct sunlight. High temperatures may trigger the protection circuit and stop charging. If the protection circuit is damaged, the battery may charge at an abnormal current or voltage, causing an abnormal chemical reaction inside it that can lead to overheating, smoke, bursting or fire.
!If the battery overheats, smokes, changes color, deforms or shows any other abnormality during use, charging or storage, stop using the product immediately. Continued use may cause the battery to overheat, smoke, burst or catch fire.
Power Precautions
1)Charge the device when it will not turn on or the battery is low.
2)The charging port is on the back edge of the device. Use the included USB cable or any standard USB cable.
3)A USB power adapter is not included. Use a USB power adapter rated at 5 V / 0.8 A output, purchased separately.
Buttons
| Button | Function / Notes |
|---|---|
| Test (Measure / Power) | Hold for 2 seconds to turn on or off. When on, press briefly to start a measurement. |
| Zero | Press briefly to zero. For everyday use, you can zero with your brewing water. For more consistent readings, zero with deionized water. RO-filtered water and distilled water also work. |
| Test (Measure / Power) | Hold for 10 seconds to force the device to shut down. Use this if the device cannot turn off normally. |
Touchscreen
When the device turns on, the touchscreen shows the READY screen.
①Tap anywhere on the screen to start measuring.
②CoffeeOS connection: ✓ connected to the app; ○ not connected.
③Battery level. Charge it when it drops below 10%.
④Swipe from left to right to open Menu.
⑤Swipe from right to left to open History.
Zeroing
- For everyday use, zero with your brewing water at room temperature.
- For more consistent readings, zero with deionized water.
- RO-filtered water and distilled water also work.
- We recommend zeroing about once a week.
ⓘ "Temp" is the reading from the sample well’s temperature sensor.
Measuring
Measuring precautions:
- To avoid damaging the device, do not leave coffee in the sample well for long.
- Clean the sample well right after each measurement.
- Close the magnetic lid while measuring to keep the reading accurate.
Measuring Coffee from Different Brew Methods
Paper-filtered coffee: pour-over, iced pour-over, ice drip and similar
- When the brew is finished, gently swirl the coffee until even, then measure.
- We recommend measuring within 1 minute of the brew finishing.
- For iced coffee, wait until the ice has fully melted, then stir well until even before measuring. This stops melting ice from changing the concentration and skewing the reading.
Immersion coffee: siphon, cold brew, French press and similar
- This coffee may carry fines and other suspended particles, so filter it through filter paper first, swirl it gently, and measure within 1 minute of filtering.
Espresso
- Espresso carries more oils and fines, so filter it through a 0.45 µm PES syringe filter (sold separately) before measuring to keep particles from affecting the reading.
- Measure within 1 minute of filtering.
- If you measure often, a centrifuge makes sample preparation faster.
Steps
ⓘ "Temp" is the reading from the sample well’s temperature sensor.
ⓘ Measure each type of brew within the stated time, as changes in temperature and concentration make readings inaccurate.
Brew Control Chart
On the result screen, tap the calculator icon at the bottom right to open the Brew Control Chart.
①First, swipe down to choose the sample type. Each brew type uses its own Gold Cup ranges on the chart.
②TDS(%): shows the TDS from this measurement. Tap the number to edit it.
③Dose(g): enter the weight of the coffee grounds.
④Yield(g): enter the weight of the brewed coffee.
⑤EXT(%): once TDS, dose and yield are entered, extraction yield is calculated and shown automatically. (Calculated from the coffee actually collected. Coffee held in the dripper, filter paper or grounds is not included.)
⑥Moisture(%): enter the moisture content of the roasted beans, 0–11.00% (entered by hand). Swipe left to reach this field. It corrects this measurement only.
⑦CO2(%): enter the residual CO2 content of the roasted beans, 0–5% (entered by hand). Swipe left to reach this field. It corrects this measurement only.
ⓘ Brew Control Chart results are saved with the TDS reading and can be viewed in History.
Scale Connection and Brewing
RS Extract connects directly to DiFluid Microbalance scales over Bluetooth. Once connected, it tracks weight and time as a live curve from the first pour. When brewing is finished, it reads the coffee weight automatically and combines it with the TDS reading to calculate extraction yield (EY).
ⓘ only DiFluid Microbalance scales are currently supported. (Support for other scales will follow.)
1. Pair RS Extract with DiFluid Microbalance
ⓘ If there are several scales nearby, double-press the D button on the scale you want to use to see its device ID, and check it before connecting.
2. Brew with the Scale Connected
3. Finish Brewing
4. Measure TDS
Settings
①Language: Simplified Chinese, Traditional Chinese, English, Japanese, Korean, German, French, Russian, Spanish, Portuguese and Arabic.
②Bluetooth: must be on to connect to CoffeeOS (on by default).
③Multiple Measurements: when on, you can compare readings across several coffees. The screen shows the number of readings and the standard deviation, so you can judge differences and consistency between samples.
④Hints: shows reminders such as how much liquid to use.
⑤Display Light: adjusts screen brightness.
⑥Auto Off: sets how long the device waits before turning off when idle. Default 10 minutes; options are Never, 3 minutes, 5 minutes and 10 minutes.
⑦Device Info: shows the device name, serial number (SN), firmware version and a QR code to download CoffeeOS.
⑧Factory Reset: press and hold, then slide right. This clears all settings and history, so use it with care.
ⓘ Connect to CoffeeOS regularly to check for and install new firmware. New firmware brings smoother operation, new features and stable performance.
ⓘ CoffeeOS lets you track, save, record, manage, convert, calculate, analyze, learn from and explore your data.
If you have trouble connecting, check the following:
- On the device: Settings > turn on Bluetooth.
- On your phone, turn on Bluetooth and location, and allow every permission CoffeeOS asks for.
- Restart RS Extract and CoffeeOS.
- If it still will not connect, contact the store where you bought it.
Download CoffeeOS
On your phone, turn on Bluetooth and location, and allow every permission the app asks for.
If the device will not connect, check in the device settings that Bluetooth is on.
Scan the QR code below to download CoffeeOS.
Updating Firmware in CoffeeOS
Check regularly for new firmware. New firmware brings smoother operation, new features and stable performance.
1)In CoffeeOS, tap Me > Device Center > RS Extract > Firmware Update.
Contact Customer Support
If you run into any problem, scan the QR code to contact customer support.
Cleaning and Care
Cleaning: wipe the device and the measurement window gently with a soft, slightly damp cloth. Do not use alcohol, acetone or other harsh cleaners.
Charging: charge when the battery is low. You can use the device while it charges.
Firmware: install firmware updates over the air through CoffeeOS for the latest features and improvements.
Storage: keep the device in a cool, dry place away from direct sunlight, heat and strong vibration.
Long-term storage: if the device will not be used for more than 3 months, charge it every 3 months to protect the battery.
Warranty Policy
Product faults that occur under normal use are repaired free of charge for one year from the date of purchase.
Not Covered by Warranty
1.Products not bought through an official authorized channel, or without a warranty certificate and valid invoice;
2.Products past the warranty period;
3.Faults or damage caused by misuse, or by modification, disassembly, repair or firmware flashing not done by DiFluid;
4.Faults or damage caused by shipping, moving or dropping after purchase;
5.Accidental or user-caused damage, such as liquid getting inside, incorrect input voltage, excessive pressure, or scratches to the screen or casing;
6.Faults or damage caused by force majeure, such as fire, earthquake or flood.
Compliance Information
Federal Communications Commission (FCC) Radiation Exposure Statement
The device has been evaluated to meet general RF exposure requirements. The device can be used in portable exposure conditions without restriction.
This device complies with Part 15 of the FCC Rules. Operation is subject to the following two conditions: (1) This device may not cause harmful interference, and (2) this device must accept any interference received, including interference that may cause undesired operation.
NOTE: The manufacturer is not responsible for any radio or TV interference caused by unauthorized modifications or changes to this equipment. Such modifications or changes could void the user’s authority to operate the equipment.
NOTE: This equipment has been tested and found to comply with the limits for a Class B digital device, pursuant to Part 15 of the FCC Rules.
These limits are designed to provide reasonable protection against harmful interference in a residential installation. This equipment generates, uses, and can radiate radio frequency energy and, if not installed and used in accordance with the instructions, may cause harmful interference to radio communications.
However, there is no guarantee that interference will not occur in a particular installation.
If this equipment does cause harmful interference to radio or television reception, which can be determined by turning the equipment off and on, the user is encouraged to try to correct the interference by one or more of the following measures: Reorient or relocate the receiving antenna; Increase the separation between the equipment and receiver; Connect the equipment into an outlet on a circuit different from that to which the receiver is connected; Consult the dealer or an experienced radio/TV technician for help.
Caution: Any changes or modifications not expressly approved by the party responsible for compliance could void the user’s authority to operate this equipment.
CE Compliance Notice
Do not use the device in environments with excessively high or low temperatures, and never expose it to strong sunlight or excessively humid conditions.
The suitable temperature range for the product and accessories is 5-45 °C.
Caution: Risk of explosion if the battery is replaced by an incorrect type. Dispose of used batteries according to the instructions.
The device has been tested to meet general RF exposure requirements. The device can be used in portable exposure conditions without restriction.
Bluetooth: 2402–2480 MHz, 3–4 dBm
Hereby, Shenzhen Digitizing Fluid Technology Co., Ltd. declares that this device is in compliance with the essential requirements and other relevant provisions of Directive 2014/53/EU.
WARNING: Disposal of a battery into fire or a hot oven, or mechanically crushing or cutting a battery, may result in an explosion.
Leaving a battery in an extremely high-temperature surrounding environment, such as sunshine, fire, or a hot surface, may result in an explosion or the leakage of flammable liquid or gas.
A battery subjected to extremely low air pressure may result in an explosion or the leakage of flammable liquid or gas.
CAUTION! Risk of fire or explosion if the battery is replaced by an incorrect type.