In-Line DryLoc pH Sensor for the Growlink Nutrient Doser
The 2751-2 is the in-line variant of the Signet 2751 family. It auto-recognizes whether the connected electrode is a pH or ORP probe and self-configures the signal chain on power-up. A field-free calibration routine lets you set zero and slope without a buffer when one isn't on hand. Out-of-range glass impedance and broken-glass detection raise an alert the moment a probe drifts past its serviceable life. That matters when a worn pH electrode is masking off-recipe feeds.
pH/ORP Smart Sensor Electronics with EasyCal and DryLoc Connection
The 4-20 mA two-wire loop output runs back to a Growlink Nutrient Doser, Connect Controller, or any standard PLC. Built-in preamplification keeps signal integrity intact for cable runs up to 1,000 feet. EasyCal handles routine recalibration with a single button press and an LED indicator. Drop the probe in pH 7 buffer, press, watch the LED. The DryLoc connector pulls apart for storage or hot-swap without exposing the contacts to feed water. The integral NEMA 4X junction enclosure keeps the wiring side sealed against wash-down and humid air.
Key Features
- DryLoc connector for in-line installation: Dry-contact electrode coupling — pull apart for service without dousing the wiring side.
- pH 0-14 / ORP ±2,000 mV operating range: Auto-recognizes the electrode and self-configures, so one head covers both measurements.
- Broken-glass and out-of-range impedance detection: Alarms when a pH bulb is cracked or the membrane has aged past usable life.
- EasyCal one-button calibration: Field-free recalibration with an LED visual indicator — no buffer juggling, no menu trees.
- 4-20 mA two-wire loop + S3L digital option: Loop output for any PLC; digital S3L available in the family for longer runs.
- Built-in preamplification, 1,000 ft cable run: Keeps signal integrity over distribution-room distances.
- NEMA 4X integral junction enclosure: Sealed against grow-room humidity and wash-down on the wiring side.
Technical Specifications
| Specification | Value |
|---|---|
| Model | GF Signet 3-2751-2 (In-line, 4-20 mA) |
| Measurement | pH and ORP (auto-recognized via electrode) |
| pH range | 0 to 14 pH (family rated -1 to 15) |
| ORP range | ±2,000 mV |
| pH response time | <6 sec for 95% of change |
| Output | 4-20 mA, two-wire loop with EasyCal |
| Alternate outputs (family) | S3L digital available on -1 and -4 variants |
| Electrode connector | DryLoc |
| Operating temperature | 32°F to 185°F (storage -4°F to 185°F) |
| Cable | 4.6 m (15 ft), 3-conductor shielded, 22 AWG |
| Cable run with preamp | Up to 305 m (1,000 ft) |
| Power supply | 12-24 VDC ±10% (4-20 mA); 5-6.5 VDC ±5% (S3L) |
| Enclosure | NEMA 4X (integral, in-line version) |
| Body material | PBT polyester |
| Diagnostics | Broken-glass alert, out-of-range glass impedance |
| Calibration | EasyCal one-button with LED indicator |
| Compatibility | Growlink Nutrient Doser System (NDS), Nutrient Doser Kit (NDK); GF 8900/9900/9950 instruments; generic 4-20 mA PLC |