3/4-260S 0.260" Bore Diameter Threaded Straight/Stepdown Thermowells

 Supported Applications

The Omega Series 260S is a standard threaded thermowell designed for temperature measurement applications requiring protection of sensing elements with a maximum diameter of 0.252" (¼"). The series accommodates bimetal thermometers, #20-gage thermocouple elements, unarmored liquid-in-glass test thermometers, and other compatible sensors. Documented compatibility includes OMEGA® NB1, NB2; PR-12, PR14, and NPT-style probes, as well as DialTemp™ Thermometers.

Applications include environments requiring corrosion resistance or chemical bath service. The series supports configurations for general use where threaded process connections are required.

Operating Conditions & Performance

The Series 260S features a fixed internal bore diameter of 0.260" with a tolerance of ±0.002" and an external thread allowance of 1". Standard insertion lengths (U) begin at 2½", while stem lengths (A) range from 4" to 24" depending on the model configuration.

Pressure ratings are temperature-dependent and vary by material, as defined in the Pressure-Temperature Rating table:

• Brass (ASTM B-16): Rated up to 5000 psi at 70°; rating decreases with increasing temperature.
• Carbon Steel (C-1018): Rated up to 5200 psi at 70°, maintaining ratings through higher temperatures compared to brass, with a maximum listed pressure of 4600 psi at 600° and 3500 psi at 800°.
• A.I.S.I. 304 Stainless Steel: Rated up to 7000 psi at 70°, with ratings extending through 1200° (1650 psi).
• A.I.S.I. 316 Stainless Steel: Rated up to 7000 psi at 70° and 200°, maintaining high pressure capability through elevated temperatures, with a rating of 2500 psi at 1200°.
• Monel®: Rated up to 6500 psi at 70°, with ratings extending through 800° (5200 psi).
The internal pipe thread is specified as NPSM, which accepts both NPT and NPS male threads.

Configuration Options

The series offers extensive configurability across process connections, materials, dimensions, and protective options to meet specific installation requirements.

• Process Connections: Standard external thread sizes include ½ NPT, ¾ NPT, and 1 NPT. Other thread sizes are available upon request.
• Materials of Construction (Wetted Parts): Brass (ASTM B-16), Carbon Steel (C-1018), Stainless Steel A.I.S.I. 304, Stainless Steel A.I.S.I. 316, and Monel®.
• Dimensions: Insertion lengths vary by model; standard configurations include insertion lengths of 2½", 4½", 7½", 10½", 13½", 16½", and 22½". Shank diameters (Q) correspond to the thread size, with specific values such as ⅝ for certain ½ NPT models and ¾ for ¾ NPT models.
• Protective Coatings: PFA coating is available. Options include resist corrosion coatings and color-coded sensors for process control.
• Accessories: Cap and chain options are offered with suffixes "-CC-BRASS" (Brass cap) or "-CC" (304 SS cap). OT-201 Conductive Silicon Paste is available to increase response rate.

Key Product Differences

Variants within the Series 260S are distinguished by external thread size, insertion length, stem length, and material selection. The model number guide follows the format: Ext Thread P - Model Number - Stem Length A - Insert Length U - Shank Dia.Q (example: 3/4-260S-U71/2-304SS).

Material specifications are indicated by suffixes in the ordering code:

• -BRASS: Brass material.
• -CS: Carbon Steel (C-1018).
• -304SS: 304 Stainless Steel.
• -316SS: 316 Stainless Steel.

The series includes both straight and stepdown configurations depending on the selected insertion length relative to the stem. Metric models are available via Omega's website, distinct from the standard inch-based variants listed in this data sheet.