1-385L 0.385" Bore Dia Threaded Lagging Extension Thermowells

Supported Applications

The Omega Series 385L is a standard threaded thermowell designed for temperature sensing applications. It accommodates standard length, ¼" stem bimetal thermometers, #14-gage thermocouple thermometers, armored liquid-in-glass test thermometers, and other temperature-sensing elements with a maximum diameter of 0.377".

These wells are compatible with OMEGA® NB1, NB2; PR-12, PR-14, and NPT-style probes, as well as DialTemp™ Thermometers. The series is intended for use in media including water, steam, air, gas, and similar density fluids.

Operating Conditions & Performance

The Series 385L features a 0.385" bore diameter to accept the specified sensor elements. Maximum fluid velocity limits vary by material and insertion length (U). For shorter insertion lengths, consideration is given to the velocity pressure effect of water flowing at higher velocities; values in parentheses represent safe values for water flow, while unbracketed values apply to steam, air, gas, and similar density fluids.

Velocity limits are documented as follows:

• Brass (ASTM B-16): 290 ft/s (water: 145) for 2½" insertion; decreasing to 8.0 ft/s at 19½".
• Carbon Steel (C-1018): 326 ft/s (water: 260) for 2½" insertion; decreasing to 7.7 ft/s at 22½".
• A.I.S.I. 304 & 316: 349 ft/s (water: 360) for 2½" insertion; decreasing to 8.0 ft/s at 22½".
• Monel: 316 ft/s (water: 320) for 2½" insertion; decreasing to 7.5 ft/s at 22½".

Pressure-Temperature Ratings are available on omega.com.

Configuration Options

The series is offered with a lagging extension type design, providing specific wrench allowance and thread allowance dimensions. Standard process connections include ¼ NPT and 1 NPT external threads; other thread sizes are available upon request. The internal pipe thread (NPSM) accepts both NPT and NPS male threads.

Configurable options across the series envelope include:

• Materials: Brass (ASTM B-16), Carbon Steel (C-1018), Stainless Steel A.I.S.I. 304, Stainless Steel A.I.S.I. 316, and Monel.
• Lagging Extension (T): Available in 2" or 3" lengths depending on the model configuration.
• Insertion Lengths (U): Offered in 2½", 4½", 7½", 10½", 13½", and 19½" inches.
• Stem Lengths (A): Available in 6, 9, 12, 15, 18, and 24 inches.
• Caps: Brass cap options add suffix "-CC-Brass"; 304SS cap options add suffix "-CC" for additional cost.

PFA coating is available. Metric models are also offered via omega.com.

Key Product Differences

The Series 385L model number follows the format: [Connection]-385L-U[Insertion Length]-[Material Code]. For example, a 1-385L-U7½-304SS denotes a thermowell with a 1 NPT external thread, 7½" insertion length, and A.I.S.I. 304 stainless steel construction.

Variations are distinguished by the combination of connection size (¼ NPT or 1 NPT), lagging extension type, stem length, insertion depth, and wetted material code (*). Material codes include "304SS" for 304 stainless steel, "316SS" for 316 stainless steel, "CS" for carbon steel, and "BRASS" for brass.