4
Important Notes
Usage for the intended purpose
The level electrodes NRG 1...-50 are used in conjunction with level switch NRS 1-50 as water level
limiters for steam boilers and (pressurised) hot water installations.
Water level limiters switch off the heating when the water level falls below the set minimum level (low water).
Function
When the water level falls below the low level, the level electrode is exposed and a low level alarm is
triggered in the level switch NRS 1-50. This switchpoint "Low water level (LW)" is determined by the
length of the electrode tip.
The electrode operation is based on the conductive measuring 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 insulation 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
protective tube mounted on site (see section
Examples of Installation
- pages 16, 17) ensures correct
functioning.
One level electrode NRG 1...-50 can be installed together with one GESTRA level electrode, one level
switch or transmitter for water level control and high level alarm in one single protection tube or level pot.
If the level electrode is installed in an isolatable level pot outside the boiler, make sure that the connec-
ting 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 ≥ 100mm, the installation is considered to be
internal. In this case the rinsing processes do not have to be monitored.
Safety note
Danger
When loosening the electrode steam or hot water might escape!
This presents the risk of severe scalding all over the body!
It is therefore essential not to dismantle the electrode unless the boiler pressure is verified
to be 0 bar.
The electrode becomes hot during operation.
Risk of severe burns to hands and arms.
Before carrying out installation and maintenance work make sure that the steam trap is cold.
Attention
The name plate specifies the technical features of the equipment. Do not commission or
operate any item of equipment that does not bear its specific name plate.
Water level limiters are safety accessories as defined in the Pressure Equipment Directive (PED) and
must only be installed, wired and commissioned by qualified and competent staff.
Retrofitting and maintenance work must only be performed by qualified staff who - through adequate
training - have achieved a recognised level of competence.
Summary of Contents for NRG 111-50
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