1/2-385A Test/Limited Space Thermowells for 0.260" & 0.385" Bore Dia

Supported Applications

The Omega Series 385A and 260A are general-purpose and limited-space thermowells designed for use with armored liquid-in-glass thermometers, thermocouples, and bimetal thermometers. These units accommodate sensors with a ¼" (0.250") diameter element.

Documented media compatibility includes water, steam, air, gas, and similar density fluids. The series supports configurations for sanitary applications via Sanitary 3A Approved Thermowells options.

Operating Conditions & Performance

The Series 385A features a ½ NPT external thread with a bore diameter of 0.385" and an overall stem length ranging from 3¼ to 13¼ inches depending on insertion depth. The Series 260A offers ¾ and 1 NPT external threads, a 0.260" bore diameter, and a fixed insertion length of 1⅝ inches with a total length of 2½ inches.

Pressure ratings vary by material and temperature for the Series 385A:

• Brass (ASTM B-16): 2810 psi @ 70°F, decreasing to 440 psi at 400°.
• Carbon Steel (C-1018): 3160 psi @ 70°F, rated down to 920 psi at 1000°.
• A.I.S.I. 304 Stainless Steel: 4120 psi @ 70°F, maintaining ratings up to 990 psi at 1200°.
• A.I.S.I. 316 Stainless Steel: 4120 psi @ 70°F, rated down to 1490 psi at 1200°.

For Series 260A pressure and velocity ratings, the documentation directs users to use values given for Series 260S Wells. Velocity rating tables indicate that unbracketed values apply to steam, air, gas, and similar density fluids, while bracketed values are specific to water flow.

Configuration Options

The series is configurable across multiple wetted materials including Brass (ASTM B-16), Carbon Steel (C-1018), A.I.S.I. 304 Stainless Steel, and A.I.S.I. 316 Stainless Steel.

• Series 385A Insertion Lengths: Available in 2, 4, 6, 8, 10, and 12 inches (U dimension).
• Series 260A Thread Sizes: Offered with ¾ NPT or 1 NPT external threads.

All wells include a captive plug & chain as standard. Additional options available upon consultation include PFA coating, Epoxy protective coatings, and color-coded sensors for process control. Cap and Chain options are offered in Brass (CC-Brass) or 304 SS (CC).

Key Product Differences

The primary distinction between the two families is their intended space constraints and thread configurations.

• Series 385A: Designed for general use with a larger bore diameter of 0.385" to accommodate specific sensor types, featuring variable insertion lengths from 2 to 12 inches on a fixed ½ NPT connection.
• Series 260A: Engineered as limited-space thermowells with a smaller 0.260" bore diameter and shorter overall profile (2½ inch length), available in larger thread sizes of ¾ or 1 NPT.

Model numbering follows the format [Thread Size]-[Series Code]-U[Insertion Length]-[Material Code]. For example, a Series 385A with ½" thread and 4-inch insertion in 304 stainless steel is ordered as 1/2-385A-U4-304SS. Material codes include 'BRASS', 'CS' for carbon steel, '304SS', and '316SS'.