NB-NEP-NS-HEADS

Supported Applications

The Omega NB, NEP, and NS series provides thermocouple heads and terminal blocks designed for connection head assemblies. These units serve as the interface point between protection tubes and extension wiring in temperature measurement systems. The product overview identifies suitability for outdoor use on moisture- and dust-resistant models, chemical plant environments where corrosion resistance is required (specifically Nylon NBN heads), and general industrial applications requiring rugged construction.

Specific configurations support hazardous location requirements with explosion-resistant designs rated for Class I, Div 1&2, Groups C, D; Class II, Div 1, Groups E, F, G; and Class III, Div 1. The series also accommodates bi-metal thermometer assemblies (Model J) as an alternative to thermocouple elements.

Operating Conditions & Performance

The series supports a range of ambient operating temperatures depending on the housing material. Nylon heads are suitable for use in ambient temperatures up to 121°C (250°F). High-temperature plastic materials are available for select models, while cast iron and metal housings provide rugged construction with painted finishes or burnished surfaces.

Environmental protection varies by model: many units feature gasketed covers that are moisture and dust resistant. Specific variants offer NEMA 4X (IP66) ratings, while the NB12 miniature aluminum head is listed as IP 67 Sealed. The series includes options with safety chains on covers to prevent loss during maintenance.

Process Connections

The heads feature threaded openings for protection tube entry and extension wire entry. Common thread sizes include:

• Protection Tube Entry: ½ NPT, ¾ NPT, 1 NPT (varies by model).
• Extension Wire Entry: ¼ NPT, ½ NPT, M10 x 1, M16 x 1.5.

Certain models include compression fittings for wire entry ranging from ⅛ to ¼" OD or nylon bushings for plastic-covered extension wires up to 0.24 to 0.40" OD.

Electrical Connections

The series supports terminal blocks with 0, 2 (single element), or 4 (duplex element) terminals. Wire capacity is typically max 14-gage wire for standard models and max 8-gage wire for heavy-duty heads like the NSA/NSB/NSC cast iron series.

Configuration Options

The NB-NEP-NS-HEADS series offers extensive configurability across housing materials, physical profiles, and terminal options to match specific installation constraints.

Housing Materials & Profiles

• Metallic Housings: Cast Iron (NB1, NB5), Burnished Die-Cast Aluminum (NB2), Standard Aluminum (NB3, NB6–8, NEPA/B, NXT), and Feraloy® Iron Alloy (HEP-TX).
• Plastic & Composite Housings: Bakelite (NB10), Glass Reinforced Nylon (NB9), Nylon (NBN), and Bakelite Glass Fiber (NBG). Sanitary Polypropylene and Stainless Steel heads are listed as available options.
• Specialized Profiles: Miniature sizes (NB4, NB10–12), Low Profile (NB12), Deep Base (NB6), Flip Top (NB7), Domed Top (NB8), Tall Cover with Hinge Top (NXT for big transmitters), and Explosion Resistant designs (NEPA/B, NEP-T).

Terminal Block Options

Terminal blocks are offered separately or included. Materials include ceramic, bakelite, and brass. Specific model numbers such as CH-49 through CH-84 correspond to single (2-terminal) or duplex (4-terminal) configurations for various head types.

Accessories & Special Options

• Ceramic Fiber Insulated Thermocouple Elements: XC Series available in Types K, E, and J with 14, 20, or 24 AWG wire sizes.
• Bi-Metal Thermometers: Model J thermometers are offered as alternatives for head and well assemblies.
• Hazardous Location Ratings: Explosion-resistant heads (e.g., NEP-T) rated for Class I, Div 1&2, Groups C, D; Class II, Div 1, Groups E, F, G; and Class III, Div 1. Note: The use of explosion resistant heads does not imply the complete assembly is explosion proof or intrinsically safe.

Key Product Differences

The series distinguishes models by physical dimensions, weight, and specific feature sets tailored to installation environments:

• NB1 (Cast Iron): Rugged construction with screw cover; standard size. Dimensions: 76 mm width x 86 mm height x 92 mm depth.
• NB2 (Burnished Die-Cast Aluminum): Medium size, lightweight, gasketed weather resistance, and safety chain on cover.
• NB4 (Aluminum Miniature): Metric design with M10 x 1 protection tube entry; uses miniature barrier strip connector. Dimensions: 48 mm width x 54 mm height x 67 mm depth.
• NBN (Nylon): Very lightweight, excellent corrosion resistance for chemical plant use; supplied with nylon bushing for plastic-covered wire. Ambient limit to 121°C (250°F).
• NEP-T & NEPA/B: Explosion-resistant designs utilizing barrier strip connectors where required.

Note: Transmitters may not be mounted in most heads; only the smallest transmitters fit NB2 by special order, and none fit NB4. Users must check transmitter dimensions against internal head specifications.