3/4-385S 0.385" Bore Diameter Threaded Straight Thermowells

 Supported Applications

The Omega Series 385S is a standard threaded thermowell designed for temperature sensing applications. It accommodates standard length, ¾" stem bimetal thermometers, #14-gage thermocouple elements, and armored liquid-in-glass test thermometers. The series supports other temperature-sensing elements with a maximum diameter of 0.377".

Documented media compatibility includes environments requiring corrosion resistance and chemical baths. These wells are compatible with OMEGA® NB1, NB2; PR-12, PR-14, and NPT-style probes, as well as DialTemp™ Thermometers.

Operating Conditions & Performance

The Series 385S features a fixed bore diameter of 0.385" (±0.002). Pressure ratings are defined by material and temperature in lb Per Square Inch (psi), with values varying across the operating envelope.

• Brass: Rated from 5,000 psi at 70° to 1,000 psi at 400°; no rating provided above 400°.
• Carbon Steel (C-1018): Rated from 5,200 psi at 70° down to 1,500 psi at 1,000°; no rating provided at 1,200°.
• A.I.S.I. 304: Rated from 7,000 psi at 70° and 6,200 psi at 200°, down to 1,650 psi at 1,200°.
• A.I.S.I. 316: Rated from 7,000 psi at 70° through 400°, maintaining high pressure up to 5,100 psi at 1,000° and 2,500 psi at 1,200°.
• Monel®: Rated from 6,500 psi at 70° down to 1,500 psi at 1,000°; no rating provided at 1,200°.

To increase response rate, the series supports the use of OT-201 Conductive Silicon Paste. The product is made in USA.

Configuration Options

The Series 385S offers configurable dimensions and materials to meet specific installation requirements.

• Process Connections: Standard external threads are available in ¾ NPT and 1 NPT. A ½ NPSM internal pipe thread is also offered, which accepts both NPT and NPS male threads. Other thread sizes are available upon request.
• Dimensions: Insertion lengths (U) range from 2½ to 22½ inches in increments of 2 inches (specifically: 2½, 4½, 7½, 10½, 13½, 16½, and 22½). Corresponding stem lengths (A) are available as 4, 6, 9, 12, 15, 18, and 24 inches.
• Wetted Materials: Available in Brass (ASTM B-16), Carbon Steel (C-1018), Stainless Steel A.I.S.I. 304 & A.I.S.I. 316, and Monel®.

Key Product Differences

Variants are distinguished by external thread size, insertion length, stem length, and material composition. Model numbers follow the format External Thread Size-385S-U (Insertion Length)<Insert Length>-(*Material). For example, a ¾ NPT thermowell with a 7½" insertion length in 304 stainless steel is ordered as 3/4-385S-U71/2-304SS.

Optional configurations include:

• Caps and Chains: Brass cap (suffix “-CC-Brass”) or 304 SS cap (suffix “-CC”).
• Protective Coatings: PFA, Epoxy, and other materials are available; consult the Sales Department.
• Sensors: Color-coded sensors for process control are offered.

Metric models are also available. For assistance in choosing head and well assemblies, visit omega.com.