High Temperature Thermocouple (S Type): India’s Complete Manufacturer Guide for Glass, Steel, Ceramics & Power Industries

There is a temperature boundary in industrial measurement above which base-metal thermocouples — your K-types, your N-types, your workhorse sensors — simply cannot operate reliably. Above approximately 1,200°C–1,300°C in continuous service, base-metal alloys oxidize, drift catastrophically, and eventually fail. The measurement problem this creates isn’t just about accuracy — it’s about process control at temperatures where a few degrees of error separates a perfect melt from a ruined batch, where refractory overheating means weeks of costly repair, and where fuel efficiency depends on operating a furnace or kiln at precisely the right temperature across all zones.

This is the territory of the High Temperature Thermocouple — the S Type (Platinum/Rhodium-Platinum), built on precious metal conductors, housed in high-purity alumina ceramic protection tubes, and engineered for continuous reliable service up to 1,500°C. This guide covers everything about Aavad’s ASWS S Type High Temperature Thermocouple: its full specification, how its construction handles the unique demands of extreme-temperature service, where it’s used across Indian industry, and how to specify the right assembly for your application.

What Is an S Type High Temperature Thermocouple?

A Type S thermocouple is a noble-metal thermocouple built from:

• Positive leg: 90% Platinum + 10% Rhodium (Pt.Rh 10%)
• Negative leg: Pure Platinum (Pt)

The precious metal composition of both conductors is the foundation of everything that makes S-type performance unique: platinum and platinum-rhodium alloys retain their thermoelectric properties at temperatures that destroy any base-metal alloy combination, they resist oxidation in the high-temperature atmospheres found in furnaces and kilns, and their thermoelectric output is among the most stable and well-characterized of any thermocouple type — making them the reference standard for calibration and the process standard for extreme-temperature measurement.

Full Specifications: Aavad ASWS S Type High Temperature Thermocouple

Why S Type Outperforms Every Base-Metal Thermocouple Above 1,200°C

The Oxidation Problem With Base-Metal Types

K-type thermocouples (Chromel/Alumel) are the standard for most industrial applications up to approximately 1,000°C–1,200°C. Above this range, the chromel and alumel alloys begin to oxidize at a rate that causes progressive, measurable calibration drift. In continuous service at 1,200°C+, a K-type thermocouple is not just reading inaccurately — it is changing its calibration curve as you watch, requiring increasingly frequent replacement to maintain any measurement integrity.

The S Type Solution

Platinum and platinum-rhodium are noble metals — they resist oxidation in high-temperature oxidizing atmospheres (the most common furnace environment) with dramatically superior stability compared to any base metal alloy. An S-type thermocouple in continuous service at 1,400°C exhibits calibration drift measured in fractions of a degree per hundred hours of service. A K-type at the same temperature would drift into single-digit-degree errors within hours and catastrophic failure within days.

The Alumina Ceramic Protection System

Noble metal thermocouple wires cannot simply be exposed to a furnace atmosphere — contamination from metallic vapors, combustion products, silicon dioxide, and other high-temperature species would rapidly degrade the platinum alloys. The alumina ceramic protection system (twin-bore Ker-710 alumina 99.7% insulator, inner and outer ceramic tubes) provides:

• Electrical isolation between the two conductor wires and between the conductors and the metallic outer sheath
• Physical protection from direct contact with furnace atmosphere, combustion gases, and particulate matter
• Structural integrity that maintains the sensor geometry inside the furnace at sustained high temperature

The Ker-710 ceramic — 99.7% alumina purity — is not a generic refractory material; it is specifically selected for its high-temperature stability, high dielectric strength, and resistance to the thermal shock that would shatter lower-purity ceramics during furnace startup cycles.

The Inconel 600 Holding Tube: Bridging the Furnace Wall

The metallic holding tube (Inconel 600, 30mm OD, 250mm length) serves a specific mechanical function: it provides the structural connection between the die-cast aluminum connection head (outside the furnace wall) and the ceramic assembly (inside the furnace atmosphere). Inconel 600’s oxidation resistance at elevated temperatures allows it to handle the furnace wall transition zone — where temperatures are below the ceramic’s primary working range but above what stainless steel would reliably survive long-term. The fixed-welded 2″ 300#RF flange provides the mechanical seal and process connection at the furnace wall penetration point.

Where High Temperature S Type Thermocouples Are Critical Across India

Glass Manufacturing — Melting, Refining & Float Lines

India’s major glass hubs: Firozabad, Agra (UP — the world’s largest glass-bangle manufacturing cluster) | Bharuch, Surat (Gujarat — industrial glass) | Kolkata, Howrah (WB — container glass) | Nashik, Pune (Maharashtra) | Hyderabad (Telangana — flat glass)

Glass melting furnaces operate between 1,400°C and 1,600°C at the melting zone. S-type thermocouples are the standard measurement technology for glass melt temperature monitoring — they are the only common thermocouple type that can deliver reliable continuous measurement at these temperatures. Crown temperatures, waist temperatures, and refiner zone temperatures are all monitored with S-type or R-type assemblies.

India’s glass industry — including container glass, flat/float glass, specialty glass, and fiberglass — represents one of the country’s most concentrated markets for noble-metal high-temperature thermocouples.

Steel and Metal Industries — Furnaces, Soaking Pits, and Melt Shops

Hubs: Jamshedpur (Jharkhand) | Bhilai (Chhattisgarh) | Rourkela (Odisha) | Durgapur (WB) | Angul (Odisha) | Visakhapatnam (AP) | Hazira, Surat (Gujarat)

Soaking pit temperatures for slab and bloom heating prior to rolling (typically 1,200°C–1,300°C), induction furnace process temperatures, and continuous casting tundish temperatures all fall in the S-type operating range. Where K-type sensors require frequent replacement, S-type thermocouples provide the long-term stability that reduces maintenance burden in steel melting shops.

Ceramics, Tiles, and Refractories

Hub: Morbi, Gujarat — India’s largest ceramics and tile manufacturing cluster, producing the vast majority of India’s ceramic floor and wall tiles

Tunnel kiln firing temperatures for floor and wall tiles typically reach 1,100°C–1,200°C. More demanding technical ceramics, advanced refractory materials, and specialty ceramics may require firing temperatures above 1,300°C — well into S-type territory. Morbi’s ceramic plants are among the largest volume users of high-temperature thermocouple assemblies in India.

Cement Industry — Burning Zone and Preheater Monitoring

Hubs: Chittorgarh, Beawar (Rajasthan) | Nalgonda (AP) | Gulbarga (Karnataka) | Porbandar (Gujarat)

Rotary kiln burning zone temperatures for cement clinker production reach 1,400°C–1,450°C. S-type or R-type thermocouples are specified for burning zone monitoring — the highest-temperature measurement point in cement kiln operation.

Aluminium Smelting and Non-Ferrous Metals

Hubs: Angul (Odisha — NALCO) | Renukoot (UP — HINDALCO) | Mettur (Tamil Nadu) | Hirakud (Odisha)

Aluminium melting and holding furnace temperatures (750°C–900°C range), and higher-temperature anode baking furnaces (up to 1,200°C+) both utilize high-temperature ceramic tube thermocouples.

Power Generation — High-Temperature Boiler Zones

Hubs: Korba (Chhattisgarh) | Ramagundam (AP) | Singrauli (MP) | Rihand, Obra (UP) | Ennore (TN) | Gandhinagar, Wanakbori (Gujarat)

Superheater and reheater steam temperature measurement, as well as combustion zone gas temperature monitoring, may require S-type thermocouples at the highest-temperature measurement points in large thermal power stations where boiler temperatures exceed the practical K-type operating range.

Aerospace, Defence, and Research

Hubs: Bengaluru (ISRO, HAL, DRDO, NAL) | Hyderabad (DRDL, BDL) | Pune (ARDE) | Thiruvananthapuram (VSSC) | Trombay (BARC)

Propulsion test rigs, materials testing furnaces, hypersonic wind tunnel instrumentation, and nuclear materials research all require the precision and stability of S-type thermocouples at extreme temperatures.

When to Choose S Type vs R Type vs B Type

For most glass, ceramics, steel, and cement applications where the operating range is up to 1,500°C, the S Type (ASWS) is the appropriate standard specification. R Type and B Type are specified where specific process requirements or temperature ranges beyond S type capability demand them — see Aavad’s Noble Metal Thermocouples and B Type Thermocouple pages.

India-Wide Coverage

Aavad Instrument supplies High Temperature S Type Thermocouples PAN India from Ahmedabad, Gujarat:

Gujarat: Ahmedabad, Vadodara, Surat, Rajkot, Morbi, Ankleshwar, Vapi, Bharuch, Dahej, Jamnagar, Gandhinagar, Porbandar, Hazira, Bhavnagar

Maharashtra: Pune, Nashik, Mumbai, Aurangabad, Nagpur, Raigad, Chandrapur

UP: Firozabad, Agra, Renukoot, Noida, Kanpur, Lucknow, Rihand Nagar

Rajasthan: Jaipur, Chittorgarh, Beawar, Kota, Bhilwara, Alwar, Jodhpur

Tamil Nadu: Chennai, Coimbatore, Mettur, Ennore, Tuticorin, Hosur

Karnataka: Bengaluru, Mysuru, Ballari, Belagavi, Gulbarga, Mangaluru

Telangana & AP: Hyderabad, Ramagundam, Kothagudem, Visakhapatnam, Nalgonda

Odisha: Bhubaneswar, Rourkela, Angul, Hirakud, Talcher, Paradip

WB: Kolkata, Durgapur, Haldia, Asansol, Howrah, Bardhaman

Jharkhand: Jamshedpur, Bokaro, Ranchi, Dhanbad

Chhattisgarh: Raipur, Bhilai, Korba, Raigarh, Bilaspur

MP: Indore, Bhopal, Singrauli, Pithampur, Jabalpur

Delhi NCR: Delhi, Noida, Gurugram, Faridabad, Ghaziabad

Kerala: Kochi, Thiruvananthapuram, Kozhikode, Thrissur

Punjab & Haryana: Ludhiana, Mohali, Gurugram, Panipat, Chandigarh

HP: Baddi, Nalagarh, Parwanoo | Uttarakhand: Haridwar, Roorkee, Kashipur

Assam: Guwahati, Numaligarh | Goa: Panaji, Vasco, Ponda

Aavad Instrument: India’s #1 High Temperature Thermocouple Manufacturer

Aavad Instrument Pvt. Ltd., Chandkheda, Ahmedabad, Gujarat:

• ISO 9001:2015 certified | NABL-accredited calibration laboratory
• 15+ years | 38M+ installations | 2,900+ customers | 12+ countries
• Trusted by BHEL, ONGC, HAL, BARC, NALCO, Indian Railways, NPCIL, L&T, MIDHANI, Torrent Pharma, Piramal Glass, Aditya Birla Group, Atul Ltd., Saint-Gobain, Cera, PepsiCo, Kohler, RVUN
• Ceramic Tube Thermocouple Manufacturer category — full range: S Type, R Type, B Type, Noble Metal, Regenerator Crown, Glass Furnace, Blast Furnace thermocouples

Frequently Asked Questions

Q1. What is a high temperature thermocouple and why is it different from a standard K-type?

A high temperature thermocouple uses precious metal (noble metal) conductors — typically Platinum-Rhodium alloys — and high-purity alumina ceramic protection tubes to operate reliably at temperatures where base-metal thermocouples (K, J, N types) fail. Base-metal alloys oxidize and drift catastrophically above approximately 1,200°C; Platinum-Rhodium alloys retain their thermoelectric stability at temperatures up to 1,500°C (S type) and beyond (B type up to 1,704°C).

Q2. What is the maximum temperature of Aavad’s S Type High Temperature Thermocouple (ASWS)?

The ASWS S Type High Temperature Thermocouple is rated up to 1,500°C in continuous service.

Q3. What is Ker-710 ceramic insulation and why is high-purity alumina used?

Ker-710 refers to high-purity alumina (Al₂O₃, 99.7% purity) ceramic insulator material. High-purity alumina is used because it maintains its mechanical integrity, high electrical resistivity, and chemical stability at extreme temperatures up to 1,700°C+, resists thermal shock during furnace cycling, and does not react with or contaminate the platinum-rhodium sensing elements — unlike lower-purity refractories that would degrade sensor accuracy.

Q4. Why is the hot junction ungrounded in S Type thermocouples?

An ungrounded (isolated) hot junction means the sensing junction does not make electrical contact with the outer protection tube. This electrically isolates the thermocouple signal circuit from the furnace structure, eliminating ground loops, stray electrical currents from furnace heating elements, and electromagnetic interference that would corrupt the measurement signal.

Q5. When should I choose S Type over B Type for a high-temperature application?

Choose S Type (up to 1,500°C) for most glass, ceramics, steel, and cement applications where 1,500°C covers your operating range. Choose B Type (600°C to 1,704°C) when your sustained operating temperature exceeds 1,500°C, or for the most extreme high-temperature industrial applications. Note that B type has very low output below 600°C, so it is not suitable as a general-purpose sensor for lower temperature ranges.

Q6. Is NABL calibration available for S Type High Temperature Thermocouples?

Yes. Aavad’s in-house NABL-accredited calibration laboratory issues traceable NABL calibration certificates for S Type thermocouples, providing the calibration documentation required for ISO quality systems, regulatory audits, and applications where measurement traceability is mandatory.

Q7. What process connection is used for furnace wall mounting?

The ASWS uses a 2″ 300#RF fixed welded flange as the standard process connection — a heavy-duty flange specification suited to the structural demands of high-temperature furnace wall penetrations. Confirm your specific furnace wall nozzle specification with Aavad’s engineering team when ordering.

Q8. Does Aavad supply High Temperature Thermocouples across all Indian states?

Yes — PAN India supply from Ahmedabad with active deployments across all major Indian industrial states including Gujarat, Maharashtra, UP, Rajasthan, Tamil Nadu, Karnataka, Telangana, AP, Odisha, WB, Jharkhand, Chhattisgarh, MP, Delhi NCR, Kerala, Punjab, Haryana, and beyond.

Buy High Temperature S Type Thermocouples from India’s #1 Manufacturer

View the product page and download datasheet ASWS_24X1750 or contact Aavad Instrument for a quote.

📞 +91 90996 22823 | ✉ hrg@aavadinstrument.com | ISO 9001:2015 | NABL Accredited | Ahmedabad, Gujarat | PAN India Supply