The document introduces the HUBA-REGISTERED TRADE MARK 681 pressure-type level sensing transmitter, which has a pressure range of 0.1 to 25 bar and supports relative and absolute pressure measurement. The transmitter has a 3x measurement range overload capacity, a minimum overload of 3 bar, and a breaking pressure of more than 200 bar. The sensor's temperature range is 0 to 70 degrees and -25 to +85 degrees, and the temperature influence of the zero point error is 0.06 to 0.02%, and the temperature influence of the full scale error is 0.015 to 0.02%.
This manual describes the Huba 681 pressure‑type level sensing transmitter, designed for fine pressure and flow measurement in corrosive liquids. It details the compensated piezoresistive sensor, stainless‑steel construction, and optional supplementary weight for stabilization in turbulent media.
Key sections cover pressure ranges, temperature compensation, output voltage/current options, intrinsic safety classifications, electromagnetic compatibility, mechanical dimensions, and cable/media selections. Electrical connection diagrams, overload protection data, and compliance with CE and IEC standards are also included.
| Pressure range | 0.1 to 25 bar (relative) |
|---|---|
| Overload protection | 3 × measurement range, min. 3 bar |
| Rupture pressure | > 200 bar |
| Temperature compensation range | 0 °C to 70 °C (0 °C‑70 °C) and –25 °C to +85 °C |
| Response time | < 1 ms |
| Output options | 0‑5 V, 0‑10 V, 0‑20 mA, 4‑20 mA (3‑wire or 2‑wire) |
| Intrinsic safety class | EEx ia IIB T4‑T6 |
| Supply voltage | 6 V (low) to 30 VDC |
| Weight (standard) | ~160 g (without supplementary weight) |
It measures relative pressure from 0.1 bar up to 25 bar.
The device can output 0‑5 V, 0‑10 V, 0‑20 mA, or 4‑20 mA, with 3‑wire or 2‑wire wiring as required.
Yes, an intrinsically safe version is available with certification EEx ia IIB T4‑T6.
The transmitter has a response time of less than 1 millisecond.