CH-TERMINAL-BLOCKS

Supported Applications

The Omega CH Terminal Blocks series provides connection interfaces for thermocouple heads and well assemblies. These terminal blocks are designed to accommodate single or duplex elements, facilitating the termination of extension wires in temperature measurement systems. The series supports configurations suitable for outdoor use, chemical plant environments, and installations requiring explosion-resistant head ratings.

Documented applications include:

• Thermocouple Head Assemblies: Connection points for ceramic fiber insulated thermocouple elements (XC Series) within various connection heads.
• Bi-Metal Thermometer Integration: Compatible with Model J bi-metal thermometer head and well assemblies, suitable for ambient temperatures up to 121°C (250°F).
• Hazardous Locations: Specific explosion-resistant head models are rated for Class I, Group C, D; Class II, Groups E, F, G; and Class III environments.

Operating Conditions & Performance

The series encompasses a wide range of connection heads constructed from materials including Cast Iron, Aluminum (Burnished Die-Cast), Bakelite, Nylon, Glass Reinforced Nylon, and Feraloy® Iron Alloy. Electrical connections are designed for terminal blocks with 2 or 4 terminals to support single or duplex elements.

Key performance parameters include:

• Wire Capacity: Most models accommodate a maximum of 14-gage wire; select heavy-duty heads (e.g., NBS, NEP-T) support up to max 8-gage wire.
• Ambient Temperature Limits: Specific configurations, such as those for Model J bi-metal thermometers, are suitable for use in ambient temperatures up to 121°C (250°F).
• Ingress Protection: Models feature moisture and dust-resistant construction. Select units offer IP 67 Sealed ratings or NEMA 4X (IP66) rated heads available upon consultation.

Hazardous Location Ratings

Certain explosion-resistant head models within the series carry specific hazardous location approvals:

• Class I, Group C, D
• Class II, Groups E, F, G
• Class III
• Note: The use of explosion resistant heads does not imply that a complete assembly is either explosion proof or intrinsically safe.

Configuration Options

The series offers extensive configurability across head materials, terminal block types, and process connections. Terminal blocks are available in ceramic (CH-83, CH-84) for NB4 heads or Bakelite (CH-76, CH-77, CH-78) for various aluminum and cast iron models.

Terminal Block Configurations

The series supports the following terminal block options:

• Single Element (2 Terminals): Models include CH-49, CH-47, CH-73, and ceramic variant CH-83.
• Duplex Element (4 Terminals): Models include CH-50, CH-48, CH-74, and ceramic variant CH-84.
• Bakelite Blocks: Available in 2-terminal (CH-76), 3-terminal (CH-77), or 4-terminal (CH-78) configurations for NB5 through NB12 heads.

Housing and Connection Options

Connection heads are available in multiple sizes, from miniature to heavy-duty standard:

• Process Connections: Threaded openings include ½ NPT, ¾ NPT, 1 NPT, M10 x 1, and M15 x 0.75.
• Wire Entry Options: Many models feature compression fittings for extension wire entry (¼ to ½ OD), while others utilize nylon bushings or standard threaded entries.
• Housing Styles: Variants include deep base, low profile, domed top, and tall cover designs with hinge tops. Some housings are equipped with safety chains that can be readily removed without tools.

Key Product Differences

The series distinguishes between standard connection heads (NB1–NB6) and specialized variants based on material, size, and environmental rating:

• NB Series Standard Heads: NB1 through NB6 offer cast iron or aluminum construction with varying weights ranging from 5 oz to 58 oz depending on the terminal block configuration.
• Miniature & Lightweight Models: The NB4 (Aluminum, Metric) and NB10/NB11 (Bakelite/Aluminum) provide miniature or ultra-lightweight construction with weights as low as 2½ oz to 6⅝ oz. NB9 utilizes Glass Reinforced Nylon for very lightweight applications.
• Heavy-Duty & Explosion Resistant: Models such as NBS (Cast Aluminum), NEP-T, and HEP-TX provide rugged construction with weights up to 75 oz or more. The HEP-TX model is constructed from Feraloy® Iron Alloy.
• Suffix Variations: Model numbers follow the pattern NB-, where terminal suffixes indicate configuration: "0" for no terminal block, "2" for single element, and "4" for duplex element. Specific heads like NB1 require a "-NB1" suffix addition to model numbers.