CMP A2F Explosive Atmosphere Cable Gland for Unarmoured Cable

Overview

The CMP A2F is a compact explosive atmosphere cable gland for unarmoured cables, and for braided cables where the braid is terminated inside the enclosure rather than in the gland. It uses a single displacement-type flameproof seal on the outer sheath of the cable, which keeps the gland short and light while still allowing certification as Ex db IIC Gb, Ex eb IIC Gb, Ex nR IIC Gc and Ex ta IIIC Da. The CMP A2F carries IECEx, ATEX, UKEX and CSA certificates, plus a wide set of national approvals and marine type approvals.

Seven Star LLC supplies the CMP A2F to instrumentation contractors, panel builders and maintenance departments in Oman and the GCC, with engineering support in Muscat. Unarmoured instrument and control cables are common inside process units, on skids and within cable trays protected by other means, and the A2F gives these circuits a certified entry into Ex d and Ex e equipment without the cost and length of an armour-clamping gland.

Sealing Principle

A flameproof gland on unarmoured cable has a single job at the joint: seal tightly enough around the sheath that the gap meets the flamepath requirements of the enclosure, while not crushing the cable. The CMP A2F does this with a displacement seal made from CMP SOLO LSF halogen-free thermoset elastomer. As the gland body is tightened, the seal is displaced inward and grips the outer sheath evenly. Because there is no armour to clamp, cable retention is rated at Type B anchorage under IEC 62444, compared with Type D for the armoured CMP types, so the installation should provide adequate cable support close to the entry.

The same sealing area also provides ingress protection. The CMP A2F is rated IP66, IP67 and IP68, with IP68 tested to a minimum of 30 metres for 12 hours, and it complies with the DTS01:91 deluge test used by offshore operators. When fitted to a parallel-threaded entry, the CMP installation instructions call for a sealing washer or O-ring at the interface to maintain these ratings.

Engineering Design of the CMP A2F

The CMP A2F is designed to BS 6121 Part 1, IEC 62444 and EN 62444, with impact Level 8 and IK10 (20 joules) for brass and stainless steel bodies. Materials offered are brass, electroless nickel plated brass, 316 stainless steel and copper-free aluminium, and the gland is rated for -60 °C to +130 °C. Protrusion lengths are short, around 26 to 37 mm for the M20 to M50 sizes, which helps in crowded terminal boxes and on small instrument housings.

The range is unusually broad at the small end. Nineteen sizes run from 16S (M16, 2.0 to 7.4 mm cable) up to 130 (M130, 97 to 114.9 mm cable), and the 16S and 20S16S sizes for very small cables are listed as ATEX, IECEx, UKEX, INMETRO, PESO and CCC certified. NPT entries from 1/2 in to 5 in are available on most sizes, and the CMP ordering reference identifies size, type, material and thread, for example 20A2F1RA5 for a nickel plated brass M20 gland.

Key Features

The main reasons to specify the CMP A2F are:

• Displacement-type flameproof seal for Ex db IIC Gb entries on unarmoured cable.
• Suitable for braided cables when the braid is terminated inside the enclosure.
• Also certified Ex eb IIC Gb, Ex nR IIC Gc and Ex ta IIIC Da for increased safety, restricted breathing and dust applications.
• Deluge protected to DTS01:91, with IP66, IP67 and IP68 ingress protection.
• Wide operating temperature range from -60 °C to +130 °C.
• Nineteen sizes from M16 to M130, including small sizes for cables down to 2.0 mm diameter.
• Short protrusion length and low weight, from 0.06 kg for the M16 and M20 sizes.
• Marine approvals from Lloyd’s Register, DNV, ABS and Bureau Veritas, plus UAE ECAS certification.

Industrial Applications

The CMP A2F is used for unarmoured instrument, signal, fieldbus and control cables entering transmitters, solenoid valves, limit switches, Ex e junction boxes and Ex d instrument housings in gas plants, refineries, terminals and chemical facilities. It is also used on fire and gas devices such as the MEDC BG Ex de manual call point and the MEDC DB3 explosion-proof alarm sounder, and on switches like the CCS 646DZE explosion-proof pressure switch, where project standards allow unarmoured cable within protected cable routes.

In Oman, the CMP A2F is relevant to instrumentation work on oil and gas concessions, at gas processing sites, at the Sohar refinery and petrochemical complex and at the Duqm industrial zone, as well as to offshore and marine installations along the coast. Seven Star LLC supplies the CMP A2F in all four materials with matching shrouds, sealing washers and locknuts, and our Muscat team checks cable outer diameters against the CMP table, which matters on unarmoured cable where the sheath alone forms the seal.

Technical Specifications

The main data for the CMP A2F is summarised below from CMP technical data sheet TDS506 Rev 23 (07/26), attached to this page with the installation instructions.

How to Order

To order the CMP A2F, send Seven Star LLC the cable outer diameter, cable type, entry thread and preferred material for each item, or share your instrument hook-up schedule for a full gland count. We supply on request with engineering support in Muscat, and the technical data sheet and installation instructions are available for download here. Our team quotes for instrumentation and electrical projects across Oman and the GCC.