5
Explanatory Notes
Scope of supply
NRG 16-11S
1 Level electrode NRG 16-11S, PN 40
1 Disk with set screw (measuring surface extension) – optional
1 Retaining ring – optional
1 Installation manual
Function
The water level limiter comprises a level electrode type NRG 16-11S and a level switch type NRS 1-7.
The level electrode NRG 16-11S consists of two concentrically arranged electrodes (measuring elec-
trode and compensating electrode) which are isolated from each other by special insulating seals.
The level limiter operation is based on the conductive measuring principle using the electrical
conductivity of water for signaling water level. During normal, trouble-free operation the level electrode
tip is immersed in boiler water and no low level alarm is given. A low level alarm will only be raised if
the electrode tip is exposed for more than 15 (25) seconds. A low level alarm will also be activated if
the insulating seals placed between the electrodes and the body are no longer pressure tight, allowing
water to penetrate into the body. However confirmation should always be done by checking if there
is water in the gauge glass. The equipment combination NRG 16-11S and NRG 1-7 provides fail safe
protection against a first fault in accordance with TRD 604.
System components
NRS 1-7
Level switch
NRS 1-7
. Two channel level limiter (redundancy) with periodic self-checking routine to
EN 50156-1.
Description NRG 16-11S
The level electrode NRG 16-11S is exclusively designed for seagoing vessels, mobile offshore platforms
and river boats. The level electrode NRG 16-11S detects the min. liquid level (low level alarm) in a
steam boiler. The operation of the electrode is based on the conductivity measuring principle using the
electrical conductivity of water for signaling one liquid level:
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Low level alarm
The NRG 16-11S is designed for use in conjunction with level switch NRS 1-7 (15 sec.) as a self-
monitoring low level limiter with periodic self-checking (SMART) feature.
Application in steam and pressurised hot-water plants in accordance with TRD 604, sheet 1 and
sheet 2 (24 h/72 h operation) as well as EN 12952 and EN 12953.
The electrical equipment meets the requirements of the Regulations on Protection Circuits EN 50156-1.
Design
NRG 16-11S
End connection: Flanged PN 40, DN 50
Electrical connection: Four-pole connector
