Since the international standards IEC 61508 and IEC 61511 for functional safety came into effect there has been an ever-increasing demand for analyzing equipment and process instruments that meet the requirements according to the SIL (Safety Integrity Level) classification. The European directives EN 12952 and 12953 demand that a hazard analysis shall be carried out for each limiting device function and appropriate levels of functional safety be implemented.
Note 1 states: Typical Safety Integrity Level (SIL) requirements for boiler protective systems are not less than 2“.
Functional safety is part of the overall safety of a system that depends on the correct functioning of safety-related (sub)systems and external equipment for risk reduction.
This means that functional safety covers only one aspect of the overall safety. Other issues such as electrical safety, fire and radiation protection etc. do not fall within the scope of functional safety. In modern systems electronic and, in particular, programmable systems perform safety functions to an ever increasing extent. As a consequence it is of utmost importance to assure the correct functioning of complex programmable systems. It is therefore essential to establish suitable methods for preventing systematic faults (usually due to human error committed during the specification and implementation phase) and for controlling
failures, abnormalities and loss of function (usually physical phenomena). In this context the term “safety integrity of the protective or safety function” is used.
The European standard IEC 61508 “Functional safety of electrical/electronic/ programmable electronic safety-related systems” defines procedures, techniques, measures etc. for the functional safety of E/E/PE systems.
The level transmitter works according to the capacitance measurement principle and translates the level changes into a level-dependent current signal of 4-20 mA, with the length of the electrode rod determining the measuring range. The level transmitter is installed inside steam boilers, vessels or in an external level pot. If the equipment is installed inside the boiler or vessel, a protection tube provided on side ensures correct functioning.
The level transmitter can be installed together with one GESTRA level electrode for water level limiting or for highlevel alarm in a single protection tube or an external level pot. The level transmitter can be used in electrically conductive and non-conductive fluids.
Directives and standards
VdTÜV Bulletin "Water Monitoring 100"
The level transmitter NRGT 26-1 is type approved acc. to VdTÜV Bulletin "Wasserstand 100" if used in combination 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. The VdTÜV Bulletin "Wasserstand (= Water Level) 100" specifies the requirements made on water level control and limiting equipment for boilers.
Approvals for Marine Applications
The level transmitter NRGT 26-1S is approved for marine applications. LV (Low Voltage) Directive and EMC (Electromagnetic Compatibility) The level transmitter NRGT 26-1 meets the requirements of the Low Voltage Directive 2014/35/EU and the EMC Directive 2014/30/EU.
ATEX (Atmosphère Explosible)
According to the European Directive 2014/34/EU the equipment must not be used in potentially explosive areas.
UL/cUL (CSA) Approval
The equipment meets the requirements of Directives: UL 508 and CSA C22.2 No. 14-13, Standards for Industrial Control Equipment. File E243189.