DiFluid RS Extract Coffee TDS Refractometer

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The DiFluid RS Extract is a professional coffee TDS refractometer made by DiFluid for roasteries, cafés, training labs and field service. It reads a sample at whatever temperature it arrives, from 4 to 65 °C, so there is no cooling step. It measures 0–30% TDS at ±0.02% precision, calculates extraction yield on its 3.5-inch colour touchscreen and keeps 500 readings on the instrument. It is IP67-rated and runs 13 hours per charge.

Read it hot, with no cooling step

Pour the sample straight from the brew, close the magnetic lid and press Test. Cooling Curve Compensation measures the temperature of the sample and of the room and calculates where the reading will settle, so the same single press works at 8 °C or 64 °C. There is no pipette rinse, no waiting for the sample to cool and no evaporation creeping into the result. Cold brew straight from the fridge, filter a minute after the kettle and an espresso shot are all read with one procedure.

Filter and espresso on one instrument

The 0–30% TDS range covers a filter brew at 1.15% and an espresso at 12% without switching modes or devices. Accuracy is ±0.02% TDS up to 4.99%, ±0.04% from 5.00 to 20.00% and ±0.06% from 20.01 to 30.00%, on a refractive index resolved to 0.00002. A reading takes under 4 seconds for a sample near room temperature; hot or iced samples take a little longer.

Extraction yield on the screen

Enter the dose and the beverage weight on the touchscreen and RS Extract calculates extraction yield beside the TDS figure. The brew control chart plots strength against extraction, and you can switch it between percolation, immersion and hybrid so the target box matches your brewer. Bean moisture and residual CO2 can be entered to correct a single measurement.

Averages, records and dial-in

Read the same sample again and the screen shows the average of the run with the spread beside it, so one stray sample never becomes your TDS. Five hundred readings stay on the instrument, each with its date, temperature and extraction, and you need no phone to take a reading or look one up later.

Record the pour with a DiFluid scale

Pair a DiFluid Microbalance scale over Bluetooth and RS Extract graphs the water, the flow rate and the time live while you pour. When the brew ends it reads the beverage weight from the scale and combines it with the TDS reading to give the extraction yield.

Built for the bar, the lab and the van

The IP67 body can be rinsed under the tap. A 3,000 mAh battery gives 13 hours of continuous measuring and 16 hours on standby, charged over USB-C, and the instrument works in rooms from 5 to 45 °C. The deepened sample well is easy to pour into, the magnetic lid seals it during a reading and doubles as a dust cap, and rebuilt heat dissipation keeps the tenth reading in a row as consistent as the first.

Linked to CoffeeOS

Over Bluetooth, the CoffeeOS app finds RS Extract by name with no pairing code, links each reading to the bean, roast and brew it came from, and installs firmware updates.

At a glance

• Reads coffee from 4 to 65 °C with Cooling Curve Compensation — no cooling step
• 0–30% TDS range, ±0.02% TDS precision, 0.01% resolution
• Extraction yield and brew control chart on a 3.5-inch colour touchscreen
• Averages repeat readings and stores 500 records on the instrument
• Magnetic sealing lid and deepened sample well
• IP67, 3,000 mAh battery: 13 h measuring, 16 h standby, USB-C
• Live brew curve with a paired DiFluid Microbalance scale
• Bluetooth link to the CoffeeOS app

• Brand: DiFluid
• Model: RS Extract (DFT-RS01)
• Measurement range: 0–30% TDS
• Precision: ±0.02% TDS
• Accuracy: ±0.02% TDS (0.00–4.99%), ±0.04% TDS (5.00–20.00%), ±0.06% TDS (20.01–30.00%)
• Resolution: 0.01% TDS
• Refractive index range: 1.33299–1.38660
• Refractive index precision: ±0.00004
• Refractive index resolution: 0.00002
• Sample temperature: 4–65 °C
• Measurement time: under 4 s (hot or iced samples take longer)
• Operating temperature: 5–45 °C
• Display: 3.5-inch colour touchscreen
• Interface languages: 11 (English, Simplified Chinese, Traditional Chinese, Japanese, Korean, German, French, Russian, Spanish, Portuguese, Arabic)
• Record storage: 500 readings (oldest overwritten when full)
• Battery: 3,000 mAh lithium-ion, non-removable
• Battery life: 13 h continuous measuring, 16 h standby
• Charging: USB-C, 5 V / 0.8 A, about 4 hours to full
• Water resistance: IP67
• Connectivity: Bluetooth (CoffeeOS app, DiFluid Microbalance scales)
• Dimensions (L × W × H): 150 × 72 × 28 mm
• Warranty: One-Year Manufacturer's Warranty

• DiFluid RS Extract refractometer × 1
• Magnetic lid × 1
• Coffee spoon × 1
• USB-C charging cable × 1
• Quick start guide × 1
• Product information card × 1
• QR code card × 1

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