The HE-300R is a 2-wire loop-powered field-installation resistivity transmitter from HORIBA's H-1 Series, designed for continuous monitoring of electric resistivity and temperature in ultrapure water systems. Powered from the 4–20 mA signal loop (24 V DC, 0.6 W max.), it requires no separate AC supply, simplifying installation and retrofitting. Combined with ERF-001 Series resistivity sensors (cell constant 0.01 /cm), it measures resistivity up to 20.00 MΩ·cm, with UPW standard resistivity input selection, clipping function, and a highly responsive temperature sensor for minimal fluctuation during sudden water temperature changes.
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HE-300R, Field-Installation Type Electric Resistivity Meter, HORIBA
HE-300R
Horiba
The HE-300R is a 2-wire loop-powered field-installation resistivity transmitter from HORIBA's H-1 Series, the simplified counterpart to the HE-200R. Powered from the 4–20 mA signal loop without a separate AC supply, it is well suited to retrofitting existing installations and simplifying wiring in new ones. Combined with the ERF-001 Series 2-electrode resistivity sensors (cell constant 0.01 /cm), it provides accurate continuous monitoring of resistivity up to 20.00 MΩ·cm in ultrapure water systems, semiconductor process water, and pharmaceutical pure water loops. A highly responsive Pt 1 kΩ temperature sensor minimises measurement fluctuation during sudden changes in water temperature, and the UPW standard resistivity input (selectable from recognised standards) supports straightforward calibration. A clipping function holds the display at a user-defined ceiling when the measured value exceeds it.
Key Features HE-300R
- 2-wire loop-powered: 24 V DC, 0.6 W max. — no separate AC supply required, simplified installation and retrofitting.
- Resistivity range 0.000–20.00 MΩ·cm / 0.00–200.0 kΩ·cm; without temperature compensation: display up to 100.0 MΩ·cm.
- Highly responsive Pt 1 kΩ temperature sensor — minimises measurement error during sudden water temperature changes.
- UPW standard resistivity input: 18.23 MΩ·cm (standard), 18.18 MΩ·cm, 18.24 MΩ·cm, 182.3 kΩ·m (standard), 181.8 kΩ·m, or 182.4 kΩ·m.
- Clipping function: display held at user-defined ceiling when measured value is exceeded.
- Temperature compensation: NaCl, arbitrary coefficient (±3%/°C, ref. 5–95 °C), or none; automatic pure water compensation in deionised water range; Pt 1 kΩ; range 0–100 °C.
- Single isolated 4–20 mA DC output (free range); max. load 600 Ω at 24 V DC (voltage-dependent — see load curve).
- Contact input (no-voltage a-contact) for external transmission hold.
- Optional transmitter and sensor combination calibration service (temperature sensor offset calibration included).
- IP65 (IEC60529 / JIS C0920); pole (50 A) or wall mount; aluminium alloy housing; SUS304 fittings and cover; reflective monochrome LCD.
- CE marked: EN61326-1, RoHS EN50581; FCC Part 15 Class A.
Applications
The HE-300R is suited to continuous resistivity monitoring in ultrapure water distribution systems, semiconductor fab process water, pharmaceutical WFI and purified water loops, and any high-purity water application where 2-wire loop-powered installation is preferred over a 4-wire AC transmitter.
Installation and Safety Notes
Power from a 24 V DC source (21–32 V DC) via the 4–20 mA loop. Maximum load resistance depends on supply voltage — consult the load curve in the product documentation. When sensor, transmission, or contact input cables are extended to 30 m or more, the CE marking surge test does not apply — fit appropriate surge absorption elements. An internal arrester (spark-over voltage 400 V) is provided. Operating temperature: −20 to 60 °C; storage: −25 to 65 °C; humidity: 5–90% RH non-condensing.
Technical Specifications
| Parameter | Resistivity, Temperature |
| Measurement method | 2-electrode resistivity (ERF-001 Series, cell const. 0.01 /cm) |
| Resistivity range | 0.000–2.000 MΩ·cm / 0.00–20.00 MΩ·cm; 0.00–20.00 kΩ·cm / 0.0–200.0 kΩ·cm; display up to 100.0 MΩ·cm (no temp. comp.) |
| Temperature range | 0–100 °C (display −10 to 110 °C); resolution 0.01 °C |
| Repeatability (resistivity) | Within ±0.1% FS |
| Linearity (resistivity) | Within ±0.5% FS |
| Repeatability / Linearity (temperature) | ±0.1 °C / ±0.5 °C |
| UPW standard resistivity input | 18.23 / 18.18 / 18.24 MΩ·cm; 182.3 / 181.8 / 182.4 kΩ·m (selectable) |
| Clipping function | User-defined ceiling; display held at ceiling when exceeded |
| Temperature compensation | NaCl (ref. 5–95 °C) / arbitrary coeff. ±3%/°C (ref. 5–95 °C) / none; auto pure water compensation; Pt 1 kΩ |
| Transmission output | 1 × 4–20 mA DC, isolated (2-wire); max. load 600 Ω at 24 V DC; free range setting |
| Contact input | 1 × no-voltage a-contact; external transmission hold |
| Power supply | 24 V DC (21–32 V DC); 0.6 W max. (2-wire loop-powered) |
| Operating temperature | −20 °C to 60 °C |
| Storage temperature | −25 °C to 65 °C |
| Humidity | 5–90% RH (non-condensing) |
| Protection rating | IP65 (IEC60529 / JIS C0920) |
| Installation | Pole (50 A) or wall mount; outdoor installation type |
| Housing material | Aluminium alloy; SUS304 fittings and cover; polycarbonate window |
| Display | Reflective monochrome LCD |
| Dimensions (W × H × D) | 180 × 155 × 115 mm (excl. mounting brackets) |
| Weight | Main body approx. 2.8 kg; cover and brackets approx. 1 kg |
| Compliance | CE (EN61326-1, RoHS EN50581); FCC Part 15 Class A |
| Manufacturer | HORIBA Advanced Techno Co., Ltd. |
| Brand | Horiba |
