Product Description
The STONEL QN45K03HDM QN45K03SDM QN4XD05HRA series represents a high performance family of flameproof limit switch boxes engineered for demanding valve automation applications requiring triple independent contact outputs. STONEL, a globally recognized brand in industrial position sensing, offers these three variants to satisfy diverse installation needs ranging from standard heavy duty service to SIL rated safety applications and extreme corrosion resistance. Each model shares a common die cast aluminum or optional stainless steel enclosure, ATEX Ex db IIC T6 flameproof certification, and three mechanically independent microswitches capable of providing open, closed, and intermediate or alarm signals from a single valve.

The STONEL QN45K03HDM is the standard heavy duty flameproof limit switch box equipped with three high current microswitches rated at 10A 250V AC. Each switch features silver cadmium oxide contacts for superior arc suppression and long electrical life exceeding one million operations. The enclosure is manufactured from precision die cast aluminum alloy with a polyester powder coating in STONEL signature blue, offering excellent resistance to impact, UV radiation, and mild chemical exposure. Three individually adjustable cam lobes allow independent setpoint configuration over 0 to 120 degrees of rotation, making this model suitable for quarter turn ball valves, butterfly valves, and plug valves as well as linear stroke actuators with appropriate linkages. The STONEL QN45K03HDM includes two M20 cable entries, an external visual position indicator with 360 degree visibility, and operates from -40°C to +85°C. This model is the workhorse for refinery shutdown valves, pipeline block valves, and compressor station isolation systems.

The STONEL QN45K03SDM is a specialized variant designed for safety instrumented system applications requiring SIL 2 or SIL 3 capability. While retaining the same triple switch configuration as the HDM model, the SDM version undergoes additional factory testing and documentation including mean time to failure calculations, proven in use data, and full traceability of components. The microswitches in the STONEL QN45K03SDM are selected for low contact resistance stability over temperature extremes and vibration resistance up to 10g. Each unit receives a unique serial number and comes with a certificate of conformance to ISO 9001 and IEC 61508 requirements. The enclosure carries the same ATEX Ex db IIC T6 certification but is additionally marked for use in SIL rated loops. Plant operators requiring documented reliability for emergency shutdown systems and high integrity pressure protection should specify the STONEL QN45K03SDM for verifiable performance.

For installations in highly corrosive environments such as offshore platforms, marine vessels, chlorine plants, or fertilizer terminals, the STONEL QN4XD05HRA offers a 316L stainless steel enclosure with an electropolished finish. This model replaces the aluminum housing with a fully welded stainless steel box rated IP66 and IP68 for continuous immersion. The STONEL QN4XD05HRA contains three mechanical microswitches rated at 5A 250V AC with gold plated contacts for low energy switching applications. The stainless steel construction eliminates galvanic corrosion when mounted on stainless steel actuators or marine grade equipment. All external fasteners are also 316 stainless steel, and the cable entries are available in M20 or 1/2 inch NPT threads. The visual position indicator uses a chemically inert polycarbonate dome with UV inhibitors. Operating temperature extends from -40°C to +120°C, suitable for steam traced lines and tropical outdoor installations. The STONEL QN4XD05HRA is the definitive choice for harsh offshore and coastal valve monitoring.

All three STONEL models share NAMUR VDI VDE 3845 mounting interfaces with a standard 30mm or 11mm square drive shaft, ensuring direct compatibility with most quarter turn pneumatic actuators from major manufacturers including STONEL, NELES, Metso, and others. The cam adjustment mechanism is accessible externally via a hex key without removing the cover, preserving the flameproof seal during setup. Each unit is pressure tested and functionally verified before shipment. For global compliance, the series holds ATEX, IECEx, and optional UKCA certifications, with SIL documentation available upon request. Plant engineers seeking a unified solution for triple contact position feedback across standard, SIL rated, and corrosive service conditions will find the STONEL QN45K03HDM QN45K03SDM QN4XD05HRA series delivers certified safety, heavy duty reliability, and application specific configurations. Trust STONEL for flameproof limit switches that perform where others fail.