GESTRA GESTRA NRS 1-50 Water Level Switch 392647

GESTRA NRS 1-50 Water Level Switch GESTRA (part of the Spirax Sarco Group) is a well-known German valve brand that has launched the high-performanceSteam boiler level limiter, designed for industrial boilers and hot water systems. It is used in conjunction with the NRG range of electrodes to ensure safe monitoring of water levels and prevent the risk of dry burning at low water levels. Compliant with SIL 3 safety standards (IEC 61508), it is suitable for a wide range of boiler water conductivity environments and supports one or two electrode configurations. AsGermany original imported valvesThe NRS 1-50 is known for its reliability and durability and is widely used in the energy, chemical and marine industries.

Product Functions and Features

• Low water level protection: When the water level falls below the minimum value set by the electrode, theGESTRA NRS 1-50 Water Level Switch An alarm will be triggered immediately and after a delay (3 seconds for standard, 15 seconds for marine applications) the safety circuit will be opened to shut down the heating system and avoid boiler damage.
• Automatic self-test and fault detection: Built-in self-test function, real-time monitoring of electrodes and connection status. If a fault is detected (e.g. broken wire or interference), the system enters a safe state and the LED indicator shows an alarm (green for normal, red for fault).
• Multi-signal output: Equipped with 2 voltage-free normally open contacts (6 A 250 V AC/30 V DC) and 2 semiconductor signal outputs (24 V DC, max. 100 mA), supporting external alarms and interlock integration.
• Rinse monitoring support: The connection logic unit SRL 6-50 is connected via the standby input and monitors the flushing process of the connection tubes (max. bypass time 5 minutes) to ensure accurate measurements.
• high security: 1oo2 architecture design, Safety Integrity Level SIL 3, 20 year life, SFF >90%. complies with TRD, EN 12952/EN 12953 standards, as well as UL 60730, FM 7710 certifications.
• Flexible Configuration: Adjust the number of electrodes by code switch, support emergency single electrode operation (need to record and repair in time).

Please refer to the official documentation for details of more features:GESTRA NRS 1-50 Data Sheet (one electrode version)The

Technical specification parameters

• Supply Voltage: 24 V DC ±20% (0.3 A) or optional 100-240 V AC +10/-15% (47-63 Hz, 0.2 A).
• power wastage: 7 VA/W.
• response sensitivity: >0.5 ~ 10 ~ <10000 μS/cm (at 25°C water conductivity).
• Enclosure and Protection: Polycarbonate, IP40 (terminal IP20), weight approx. 0.5 kg.
• sizes: 100 x 74 x 120 mm for easy mounting on the control cabinet rail (TH 35).
• Environmental adaptation: Operating temperature -10°C ~ 55°C, relative humidity up to 95% (no condensation), altitude up to 2,000 m above sea level.
• connection requirement: Shielded multi-core cable (min. 0.5 mm²), max. length 100 m (10 μS/cm sensitivity) or 30 m (0.5 μS/cm).

Please download the detailed specifications:GESTRA NRS 1-50 Data Sheet (two electrode version)The

Application Areas

GESTRA NRS 1-50 Water Level Switch Widely used inSteam boiler level control, hot water equipment protection and marine systems. AsGerman valve brandsof the representatives to which it applies:

• Steam boilers (EN 12952/EN 12953 standard).
• Pressurized hot water plants.
• Electric heating boilers and high availability redundant systems.
• Marine applications (DNV/LR standards). Not suitable for use in potentially explosive atmospheres (electrodes require additional barriers).

In industrial scenarios, it ensures safe boiler operation, reduces the risk of downtime and increases system efficiency.

Installation and Maintenance Guide

• Installation steps: Fixed to the TH 35 rail and powered using a safety power supply. When connecting the electrodes, use a shielded cable and ground it to the control cabinet center point (CEP). The external safety circuit requires the addition of an interlock function (in accordance with EN 50156).
• Connection Tube Requirements: Steam pipe ≥ 40 mm, water pipe ≥ 100 mm (internal installation does not need to be flushed and monitored); external level tanks need to be flushed regularly and equipped with a drainage device.
• Maintenance Note: Annual check of switch points; use test button to simulate alarm. Requires 24 hours thaw time after shipping. Avoid high-frequency interference (use RC combo and ferrite ring).
• Security tips: Installation to be operated by a professional; terminals are energized during operation and disposed of after power failure. External fuse: 0.5 A (half delay).

Installation manual download:GESTRA NRS 1-50 Installation Guide (two electrode version)The