Temperature Instrument Series

Industrial Bimetallic Thermometers

Field-reading mechanical temperature gauge for -80°C to +500°C. Measures liquid, vapor, and gas temperature directly on-site with zero power consumption. Available in axial, radial, 135°, and universal stem orientations with 304/316/316L/Hastelloy C-276 protection tubes.

WSS Series-80~500°CClass 1.5IP55
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Industrial Bimetallic Thermometer WSS Series

Why Choose Bimetallic Thermometers?

Bimetallic thermometers are field-reading mechanical instruments for measuring low to medium temperatures from -80°C to +500°C. They work by the differential thermal expansion of two bonded metal strips wound into a helical coil. As temperature changes, the coil winds or unwinds, rotating a pointer across a calibrated dial face. This purely mechanical operation means zero electrical power is required — no batteries, no wiring, no signal cables.

This makes bimetallic thermometers ideal for remote locations, hazardous areas, and applications where simplicity and reliability matter most. Four stem orientations — axial (bottom entry), radial (back entry), 135° angle, and universal (adjustable) — allow installation on virtually any pipe, vessel, or duct regardless of orientation. Seven mounting options including movable and fixed threads, flanges, and sleeve connections ensure compatibility with your existing process fittings.

Protection tube materials range from standard 304 stainless steel to 316L and Hastelloy C-276 for aggressive chemical environments. Manufactured to JB/T8803-1998 standard with Class 1.0 or 1.5 accuracy, IP55 protection, and thermal response within 40 seconds. Dial diameters of 60mm, 100mm, and 150mm are available. For applications requiring automatic control, the WSSX electric contact version adds relay-based upper/lower limit alarm output.

Technical Specifications

ParameterSpecification
Product StandardJB/T8803-1998
Temperature Range-80°C to +500°C (9 standard ranges)
Accuracy Class1.0 / 1.5
Dial DiameterΦ60, Φ100, Φ150 mm
Stem DiameterΦ6, Φ8, Φ10 mm
Stem Length (L)75, 100, 150, 200, 300, 400, 500, 750, 1000 mm
Stem Material1Cr18Ni9Ti / 304 / 316 / 316L / Hastelloy C-276
Protection LevelIP55
Thermal Response≤40 s
Stem OrientationsAxial, Radial, 135°, Universal
Thread ConnectionsM16×1.5, M20×1.5, M27×2, NPT1/4, NPT1/2, NPT3/4
Working EnvironmentSheltered: -25~+25°C / Outdoor: -40~+85°C, RH 5~100%

Key Features

Zero Power Required

Operates purely on mechanical thermal expansion. No batteries, no wiring, no signal cables — just mount and read. Ideal for remote or hazardous locations.

Multiple Stem Orientations

Choose axial (bottom entry), radial (back entry), 135° angle, or universal (adjustable) to suit any pipe or vessel installation angle.

Broad Temperature Coverage

Single instrument covers -80°C to +500°C across 9 standard ranges. Suitable for cryogenic, ambient, and high-temperature processes.

Corrosion-Resistant Materials

Protection tubes in 304, 316, 316L stainless steel, or Hastelloy C-276. Handles aggressive chemicals, marine environments, and food-grade requirements.

7 Mounting Options

Non-fixing, movable external/internal thread, fixed screw, fixed flange, sleeve screw, and sleeve flange. Metric and NPT thread connections available.

Electric Contact Option

WSSX models add automatic upper/lower limit alarm with relay output. Rated 10VA, 220V/24V. Explosion-proof dIIBT4 version available for hazardous areas.

Stem Orientations & Selection

Choosing the right stem orientation ensures the dial is readable from your operating position. Each orientation uses a different model number suffix.

OrientationCodeStem EntryDial FacesBest For
Axial0 (WSS-X0X)BottomUpwardVertical pipes, tanks from above
Radial1 (WSS-X1X)BackForwardHorizontal pipes at eye level
135° Angle2 (WSS-X2X)AngledAngled downOverhead pipes, reading from below
Universal8 (WSS-X8X)AdjustableAny directionVariable angles, maximum flexibility
Bimetallic Thermometers Stem Orientations and Selection

How to Order — Model Designation

Our WSS/WSSX model codes follow a systematic naming convention. Understanding the code helps you specify exactly what you need, or simply use the quick selection table below.

Model Code Structure: W S S _ _ _ _
WSS / SXDialOrientationMountingProtection
Temperature
instrument		Metal
expansion		SS = Standard
SX = Electric contact		3 = Φ60
4 = Φ100
5 = Φ150		0 = Axial
1 = Radial
2 = 135°
8 = Universal		0 = None
1 = Ext thread
2 = Int thread
3 = Fixed screw
4 = Fixed flange
5 = Sleeve screw
6 = Sleeve flange		(blank) = Standard
W = Weather-proof
F = Corrosion-proof
Your NeedModelDialOrientationMounting
Basic pipe monitoringWSS-401Φ100AxialExt thread
Tank side readingWSS-411Φ100RadialExt thread
Tight space overheadWSS-421Φ100135°Ext thread
Adjustable angle viewWSS-481Φ100UniversalExt thread
With alarm outputWSSX-411Φ100RadialExt thread
Hazardous area + alarmWSSX-481BΦ100UniversalExt thread
Corrosive environmentWSS-401 + C-276Φ100AxialExt thread

Typical Applications

Chemical Processing

Monitor reactor, distillation column, and heat exchanger temperatures. Hastelloy C-276 stems resist aggressive acids, chlorides, and solvents.

Oil & Gas

Pipeline and wellhead temperature monitoring. Explosion-proof WSSX versions with alarm contacts for safety-critical zones and remote wellsites.

Food & Beverage

Pasteurization, fermentation, and CIP process monitoring. 316L stems meet hygiene requirements. No electronics to sanitize or shield from washdown.

HVAC & Boiler Rooms

Boiler supply/return, chiller loops, and ductwork temperature indication. Large dials for quick visual checks at distance without instrumentation power.

Water & Wastewater

Influent/effluent and digester temperature monitoring. Thread and flange mounting options accommodate diverse pipe sizes from DN15 to DN200.

Power Generation

Steam line, condenser, and cooling tower temperature indication. Universal stem orientation handles complex pipe routing in plant environments.

Sheathed Thermocouples

Sheathed Thermocouples

Mineral-insulated Type K/J/T/N thermocouples for -40~1300°C. Fast response, flexible routing, high vibration resistance.

Assembled Thermocouples

Assembled Thermocouples

Modular junction-box thermocouples with wide type selection (K/N/E/J/T/S/R/B). Easy sensor element replacement in the field.

HM100 Temperature Transmitter

HM100 Temperature Transmitter

4-20mA integrated transmitter with Pt100 RTD input. -50~500°C range. DIN-B head mount for direct pipe installation.

Frequently Asked Questions

WSS models are standard bimetallic thermometers for visual reading only. WSSX models add electric contact points that trigger relay-based alarms when temperature reaches upper or lower setpoints. WSSX is ideal when you need automatic temperature control or alarming without additional transmitters. The electric contact version is available in standard and explosion-proof (dIIBT4) configurations.

Axial (code 0): stem enters from bottom, dial faces up — best for vertical pipes viewed from above. Radial (code 1): stem enters from back, dial faces forward — best for horizontal pipes at eye level. 135° (code 2): angled reading for overhead pipes viewed from below. Universal (code 8): fully adjustable angle, most flexible — use when pipe orientation varies or you need the dial visible from a specific direction.

The sensing tip should reach the center third of the pipe or vessel cross-section. For pipes, a common rule is: L = wall thickness + insulation thickness + immersion depth (typically 50–100mm into the flow). Standard lengths range from 75mm to 1000mm in 9 increments. Custom lengths beyond 1000mm are available on request.

Yes. Select the protection tube material based on your process media: 304 SS for mild environments, 316/316L for chloride-containing or moderately corrosive media, and Hastelloy C-276 for strong acids, chlorine, and highly corrosive conditions. Add the “F” suffix to the model code for a corrosion-proof housing.

Standard accuracy is Class 1.5 (±1.5% of full scale). Class 1.0 (±1.0%) is available for tighter tolerance applications. Angle adjustment error is within 1.0% of range. Return difference (hysteresis) does not exceed the absolute value of the basic error limit. Repeatability is within ½ the basic error limit.

Yes, periodic calibration is recommended — typically annually for industrial applications. The instrument can be field-verified against a reference thermometer or returned to our calibration lab. The dial has an adjustable zero-point screw for minor field corrections.

The explosion-proof WSSX-B version is rated dIIBT4 per Chinese NEPSI standards (equivalent to ATEX/IECEx Zone 1). It can be used in hazardous areas with explosive gas atmospheres (Groups IIA and IIB, temperature class T4). Dial diameter is fixed at Φ100 for explosion-proof versions.

WSSX models use mechanical contact switching driven by the bimetallic element. When temperature reaches a setpoint, the contact arm closes or opens a circuit. Configuration options: upper/lower limit (M, default), double upper limit (W), or double lower limit (F). Rated at 10VA, maximum 220V AC or 24V DC, 0.7A — suitable for driving relays, indicators, or PLC digital inputs directly.

Need a Custom Bimetallic Thermometer Configuration?

Our temperature engineering team can help you select the right model, stem orientation, length, material, and mounting for your specific process conditions. Whether you need standard WSS visual gauges or WSSX alarm-equipped versions, we provide complete specification support and competitive factory-direct pricing.

Our engineers typically respond within 12 business hours with detailed technical specifications and pricing.

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