The STONEL QX35K05SDM QX44K02HDM QX44K03HDM QX45CK02HDM series is a comprehensive family of heavy duty and flameproof limit switch boxes engineered to meet diverse valve position feedback requirements across hazardous and general industrial environments. STONEL, a trusted brand in automation accessories, offers these four models to address applications ranging from SIL certified safety loops and high density multi contact monitoring to compact dual switch configurations and pre wired explosion proof enclosures. This series is ideal for oil refineries, chemical plants, power generation facilities, offshore platforms, pipeline stations, and water treatment systems where reliable valve status indication is critical.

The STONEL QX35K05SDM is a flameproof limit switch box featuring five independent mechanical microswitches with SIL 2 capability per IEC 61508. Housed in a die cast aluminum enclosure certified ATEX II 2 G Ex db IIC T6, this model provides five SPDT contact outputs rated at 6A 250V AC. Each switch is individually tested and documented with full traceability, making this unit suitable for safety instrumented functions requiring verified reliability. Five externally adjustable cam lobes allow independent setpoint tuning over 0 to 120 degrees without opening the flameproof cover. The STONEL QX35K05SDM includes two M20 cable entries, a high visibility visual position indicator, IP66 IP67 ingress protection, and operates from -40°C to +85°C. This model is the preferred choice for emergency shutdown valves and high integrity pressure protection systems requiring multiple SIL certified feedback channels.

The STONEL QX44K02HDM is a heavy duty limit switch box designed for standard industrial applications where dual contact feedback is sufficient. The enclosure is constructed from die cast aluminum with a durable polyester powder coating, rated IP66 and IP67. Two mechanical snap action microswitches provide SPDT contacts rated at 10A 250V AC, capable of direct switching of solenoids and pilot devices. External cam adjustment allows stroke setting from 30 to 120 degrees, and a large visual position indicator with red green sectors ensures clear local status. Two M20 cable entries are standard, and the operating temperature spans -40°C to +85°C. The STONEL QX44K02HDM is an economical and robust solution for isolation valves, pump recirculation lines, and general process valve monitoring.

For applications requiring triple contact outputs, the STONEL QX44K03HDM offers three independent microswitches within the same heavy duty aluminum enclosure as the K02 model. Each switch is rated at 10A 250V AC, providing three SPDT signals for valve open, valve closed, and an intermediate position alarm or solenoid interlock. Three individually adjustable cam lobes allow independent setpoint configuration. The STONEL QX44K03HDM retains IP66 IP67 protection, two M20 entries, external visual indicator, and wide temperature range. This model is ideal for valve sequencing, partial stroke indication, or applications where a third signal is needed for remote annunciation or control logic.

The STONEL QX45CK02HDM is a flameproof limit switch box with a factory pre wired 2 meter heavy duty cable, eliminating the need for field wiring and cable entries. Certified ATEX II 2 G Ex db IIC T6, this model houses two mechanical microswitches rated at 6A 250V AC. The pre wired configuration significantly reduces installation time and eliminates potential moisture ingress points through improperly sealed conduit entries. The STONEL QX45CK02HDM includes external cam adjustment, a bright visual position indicator, IP66 IP67 protection, and operates from -40°C to +85°C. This model is particularly suited for offshore topside modules, pre fabricated valve skids, and installations where quick clean wiring is essential.

All four STONEL limit switch models share NAMUR VDI VDE 3845 mounting interfaces with standard drive shaft adapters for 9mm, 11mm, and 14mm square or double D actuator stems, ensuring direct compatibility with most quarter turn pneumatic and electric actuators. The die cast aluminum construction provides excellent mechanical strength and thermal stability. External cam adjustment allows stroke setpoint changes without compromising enclosure seals or flameproof certification. Each unit undergoes full functional testing before shipment, and optional ATEX, IECEx, and SIL documentation is provided. For plant engineers and maintenance teams seeking a versatile family of position switches that spans SIL rated five contact, general purpose dual and triple contact, and pre wired flameproof dual contact configurations, the STONEL QX35K05SDM QX44K02HDM QX44K03HDM QX45CK02HDM series delivers application matched reliability. Trust STONEL for certified, durable, and precise valve position feedback in any industrial environment.