Killark GRMT-1 Zone 1 Explosion-Proof Junction Box

The Killark GRMT-1 is an explosion-proof junction box (terminal box) designed for Zone 1 and Zone 2 classified hazardous areas, certified to ATEX II 2G Ex d IIC T6 and IECEx Ex d IIC T6 — the highest gas group certification (IIC, covering hydrogen) — and additionally UL 1203 listed for NEC Class I Division 1 and Division 2 applications. The GRMT-1 is manufactured from cast aluminium alloy with a precision-machined flat-face cover joint (not a threaded cover) sealed by a captive stainless steel bolt arrangement, ensuring the explosion-proof flameproof Ex d integrity is maintained over the full service life of the enclosure without depending on thread condition or thread engagement depth. The terminal compartment is sized for DIN rail mounting of standard 2.5mm² and 4mm² terminal blocks, accommodating up to 12 terminal positions in the standard size — sufficient for the multi-cable field junction functions required in Aramco instrumentation and control wiring circuits.

At Aramco facilities, explosion-proof junction boxes are used as field marshalling points for instrument signal and power cables at Zone 1 locations where the cable run configuration requires a junction between the control room cable and the local field instrument or actuator. In areas such as GOSP unit flare header areas, crude oil storage tank farm manifold areas, wellhead Christmas tree areas, and gas compression station process areas — all classified as Zone 1 under Aramco's SAES-E-006 — the junction boxes aggregate instrument signals from multiple field devices (pressure transmitters, temperature elements, level switches, control valve positioners) before the cables enter the hazardous area barrier separating Zone 1 from the safe area or instrument room. Killark's GRMT range is a long-established part of Aramco's instrumentation materials standard for Zone 1 junction boxes, alongside competing products from Crouse-Hinds and Pepperl+Fuchs.

The IIC gas group certification of the GRMT-1 means it is also rated for hydrogen atmospheres — a requirement at Aramco and SABIC facilities where hydrogen is produced or handled as a process material. At SABIC's Jubail ethylene crackers, fertiliser plants, and methanol facilities, hydrogen-rated Ex d IIC junction boxes are mandatory in Zone 1 areas near hydrogen compression and storage systems. The GRMT-1's flat-face cover design is preferred by Aramco and SABIC inspection teams because the cover joint condition is visually verifiable (bolt count, bolt engagement, and face gap are all visible) without requiring specialised inspection tools, simplifying the periodic hazardous area inspection programme required by IEC 60079-17.

Razz Middle East stocks Killark GRMT junction boxes in Dammam in the most common sizes for Aramco and SABIC projects, including the GRMT-1 standard and GRMT-2 extended versions. Hubbell Killark ATEX/IECEx certificates, detailed drawings, and material certificates are provided for Aramco and SABIC project material submittals. Razz Middle East also stocks Killark cable glands and conduit fittings to provide a complete hazardous area enclosure solution.