4
Important notes
Usage for the intended purpose
The level electrode NRG 26-21 is used for continuous level monitoring in steam boilers and (pressu-
rized) hot-water installations or in condensate and feedwater tanks. In conjunction with the level switch
NRS 2-.. and the level controller NRR 2-.. the electrode can be used as water level controller with
MIN/MAX alarm.
The level electrode is designed for use in conjunction with the following level switches/controllers:
NRS 2-50, NRS 2-51, NRR 2-50, NRR 2-51, NRR 2-52 and NRR 2-53 or NRS 2-1, NRR 2-1, NRR 2-2
and NRT 2-1.
The electrode can be used in electrically conductive and non-conductive fluids.
Function
The level electrode and the electronic module NRV 2-29 work according to the capacitance measure-
ment principle and translate the level changes into a level-dependent current signal, with the length of
the electrode rod determining the measuring range.
The level electrode is installed inside steam boilers, vessels or in an external level pot. If the electrode
is installed inside the boiler or vessel, a protection tube provided on side ensures correct functioning.
(see section
Examples of installation
(page 10).
The level electrode can be installed together with one GESTRA level electrode for water level limiting or
for high-level alarm in a single protection tube or external level pot.
Safety note
Danger
When loosening the level 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 level electrode becomes hot during operation.
Risk of severe burns to hands and arms.
Before carrying out installation and maintenance work make sure that the equipment 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.
The equipment 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.
