GESTRA NRG 16-51, NRG 17-51, NRG 19-51, NRG 111-51

High-Level Alarm Level Electrode

GESTRA NRG 16-51, NRG 17-51, NRG 19-51, NRG 111-51 High-Level Alarm Level Electrode
GESTRA NRG 16-51, NRG 17-51, NRG 19-51, NRG 111-51 High-Level Alarm Level Electrode
GESTRA NRG 16-51, NRG 17-51, NRG 19-51, NRG 111-51 High-Level Alarm Level Electrode

GESTRA NRG 16-51, NRG 17-51, NRG 19-51, NRG 111-51 High-Level Alarm Level Electrode

The level electrodes NRG 1…-51 are used in conjunction with level switch NRS 1-51 as high level alarm for steam boiler plants and (pressurized) hot water installations.

A high level alarm prevents the water level from exceeding the preset max. water level (HW) and for this purpose switches off e. g. the feedwater supply

When the level exceeds the max. water level, the level elec- trode enters the liquid and an alarm is triggered in the level switch NRS 1-51. The switchpoint “High level (HW) exceeded” is dictated by the length of the electrode rod.

The electrode operation is based on the conductive measur- ing principle using the electrical conductivity of the water for signalling water level. The self-monitoring function ensures that an alarm will also be triggered if the electrode insula- tion is contaminated or has developed a leak or if there is a malfunction in the electrical connection.

The level electrode is installed inside steam boilers, vessels or inlet lines of hot-water systems. The protection tube provided on site ensures the correct functioning.

One level electrode NRG 1…-51 can be installed together with one GESTRA water level limiting electrode in a single protection tube or external level pot.

If the level electrode is installed in a level pot outside the boiler, make sure that the connecting lines are rinsed regularly. In addition, the logic unit SRL is required to monitor the purging times and the purging sequence.

If the connecting lines for steam ≥ 40 mm and water ≥ 100 mm, the installation is considered to be internal. In this case the rinsing processes do not have to be monitored.

Service pressure

NRG 16-51, PN 40, 32 bar at 238 °C

NRG 17-51, PN 63, 46 bar at 260 °C

NRG 19-51, PN 160, 100 bar at 311 °C

NRG 111-51, PN 320, 183 bar at 357 °C

Mechanial connection

Screwed G¾ A, ISO 228-1 (NRG 16-51, NRG 17-51, NRG 19-51)

Screwed G1 A, ISO 228-1 (NRG 111-51)

Materials

Screw-in body: 1.4571 X6 CrNiMoTi 17-12-2 (NRG 16-51, NRG 17-51, NRG 19-51)

Screw-in body: 1.4529 X1NiCrMoCuN25-20-7 (NRG 111-51)

Measuring electrode: 1.4571 X6 CrNiMoTi 17-12-2 (NRG 16-51, NRG 17-51, NRG 19-51)

Measuring electrode: 1.4122 X39CrMo17-1 (NRG 111-51)

Electrode tip: 1.4401 X5 CrNiMo 17-12-2 Electrode insulation: PEEK (NRG 16-51, NRG 17-51, NRG 19-51)

Electrode insulation: special ceramic (NRG 111-51) NRG 1…-51: Four-pole connector: polyamide (PA) NRG 1…-51F: Terminal box 3.2161 G AlSi8Cu3

Lengths available

500 mm, 1000 mm, 1500 mm

pH value

Max. admissible: 10 (only NRG 111-51)

Electrical conductivity

Max. admissible: 100 μS/cm at 25 °C (only NRG 111-51)

Electrical connection

NRG 1-51: Four-pole connector, cable gland M19 (PG 11)

NRG 1…-51F: Aluminium terminal box, cable gland M20

Protection

IP 65 to EN 60529

Admissible ambient temperature

Max. 70°C

Weight

Approx. 1.2 kg (without extension) (NRG 16-51, NRG 17-51, NRG 19-51)

Approx. 2.1 kg (without extension)

(NRG 16-51F, NRG 17-51F, NRG 19-51F)

Approx. 1.8 kg (without extension) (NRG 111-51) Approx. 2.7 kg (without extension) (NRG 111-51F)

GESTRA NRG 16-51, NRG 17-51, NRG 19-51, NRG 111-51

High-Level Alarm Level Electrode

GESTRA: The Ultimate Solution for Industrial Steam & Fluid Control Systems

High-Level Alarm Level Electrode for Advanced Boiler Safety Systems

The GESTRA NRG 16-51, NRG 17-51, NRG 19-51, and NRG 111-51 High-Level Alarm Level Electrode are precision-engineered safety devices designed to protect steam and hot-water boiler systems from dangerous high-water conditions. These electrodes play a critical role in preventing water carryover, turbine damage, and system inefficiencies.

Manufactured by GESTRA Germany, the NRG 51 series is trusted worldwide for exceptional accuracy, long-term reliability, and compliance with international boiler safety standards.

GESTRA is a global authority in boiler automation and safety control technology, offering solutions that exceed industry expectations.

Key Benefits of GESTRA NRG 51 Series:

  • ✅ Precise high-level water detection

  • ✅ Fail-safe alarm activation

  • ✅ Robust stainless steel construction

  • ✅ Excellent resistance to pressure, temperature, and steam

  • ✅ Seamless integration with GESTRA level controllers

  • ✅ Long service life with minimal maintenance

The GESTRA NRG 16-51 is a conductivity-based level electrode designed specifically for high-level alarm applications in industrial boiler systems.

Features:

  • Accurate detection of maximum water level

  • Durable electrode design for continuous operation

  • Stable performance under varying boiler conditions

  • Ideal for standard steam and hot-water boilers

This model ensures early warning and protects downstream equipment from water carryover.

The GESTRA NRG 17-51 High-Level Alarm Level Electrode offers improved performance in systems with higher operating pressures.

Advantages:

  • Fast response to rising water levels

  • Optimized for demanding industrial environments

  • Resistant to corrosion and thermal stress

  • Reliable signal transmission to alarm controllers

It is widely used in process plants and high-capacity boiler installations.

The GESTRA NRG 19-51 is designed for extreme boiler operating conditions, delivering precise high-level alarm signaling even in high-pressure steam applications.

Key Highlights:

  • Exceptional measurement accuracy

  • Heavy-duty mechanical construction

  • Long operational lifespan

  • Consistent performance in harsh environments

This model is the preferred choice for power plants and critical industrial systems.

The GESTRA NRG 111-51 represents the most advanced technology in High-Level Alarm Level Electrode systems.

Benefits:

  • Highly sensitive water level detection

  • Suitable for modern automated boiler control systems

  • Compatible with GESTRA safety and alarm units

  • Complies with international boiler safety regulations

This electrode is ideal for high-risk applications requiring immediate alarm response.

GESTRA NRG 51 series electrodes are used in a wide range of industries, including:

  • Steam boiler systems

  • Hot-water boilers

  • Power generation plants

  • Oil & gas facilities

  • Chemical and petrochemical plants

  • Food & beverage production

  • Pharmaceutical manufacturing

A High-Level Alarm Level Electrode is essential to prevent:

  • Water carryover into steam lines

  • Damage to turbines and valves

  • Reduced steam quality

  • Costly shutdowns and safety incidents

Using original GESTRA High-Level Alarm Electrodes ensures system protection, regulatory compliance, and operational efficiency.

Choosing original GESTRA NRG 16-51, 17-51, 19-51, or 111-51 guarantees:

  • Authentic German engineering

  • Full product traceability

  • Superior durability and accuracy

  • Manufacturer-approved safety standards

Upgrade your boiler safety system with GESTRA High-Level Alarm Level Electrodes and ensure reliable protection against high-water conditions.

🔹 Maximum safety
🔹 Precise detection
🔹 Proven reliability

Contact us today for pricing, technical consultation, and fast delivery of GESTRA NRG 16-51, NRG 17-51, NRG 19-51, and NRG 111-51.

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