Explore our CE-certified, heavy-duty mechanical pressure gauges, capillary bi-metal thermometers, and industrial transducers engineered for critical continuous processing environments.
In complex process engineering, thermal monitoring at remote or hazardous locations requires unyielding reliability, mechanical autonomy, and extreme precision. Rototherm-style capillary thermometers represent the benchmark in remote-reading thermal measurement technology. By utilizing liquid, vapor, or inert gas thermal expansion systems coupled via micro-bore armor tubing, these instruments transmit physical temperature changes across distances extending up to 50 meters without requiring external electrical power.
As a global tier-one OEM factory, Huzhou Accuracy Instrument Co., Ltd. manufactures CE-certified capillary thermometers and bi-metal temperature assemblies designed according to EN 13190 standards. This whitepaper analyzes the engineering architecture, materials science, manufacturing quality controls, compliance protocols, and technical selection criteria essential for procurement directors and plant engineers specifying capillary temperature monitoring solutions worldwide.
Employs non-toxic, eco-safe Nitrogen ($N_2$) expansion under high pressure, providing rapid thermal response times ($T_{90} < 5\text{s}$) across wide operating ranges (-200°C to +800°C).
AISI 316L stainless steel spiral interlock capillary armor with optional PVC or PTFE sleeving ensures total physical protection against mechanical crushing and aggressive chemical environments.
Helical spring Bourdon elements made from pre-aged Beryllium Copper or AISI 316Ti deliver ±1.0% full-scale accuracy over hundreds of thousands of duty cycles.
Fully certified under the Pressure Equipment Directive (PED 2014/68/EU) and EN 13190 standards for safety, material traceability, and industrial quality.
Modern industrial applications require severe ambient temperature compensation and heavy-duty vibration resistance. Huzhou Accuracy Instrument's design roadmap integrates full environmental compensation mechanisms within the instrument housing to nullify ambient temperature fluctuations along the capillary tube path.
| Engineering Specification | Class 1 Capillary System (Gas Filled) | Class 5 Capillary System (Organic Liquid Filled) | Bimetal Direct/Stem System |
|---|---|---|---|
| Operating Range | -200°C to +800°C (-328°F to +1472°F) | -40°C to +250°C (-40°F to +482°F) | -70°C to +600°C (-94°F to +1112°F) |
| Standard Accuracy Class | Class 1.0 (±1.0% of span per EN 13190) | Class 1.0 / Class 1.5 | Class 1.0 (±1.0% per EN 13190) |
| Max Capillary Length | Up to 50 meters (164 ft) with bimetallic link comp. | Up to 15 meters (49 ft) | Direct rigid stem (N/A) |
| Capillary Armor Options | Stainless Steel 304/316 braid, SS armor tube, PVC coat | Stainless Steel braid, PVC armor coating | N/A (Rigid Stem up to 2000mm) |
| Case Protection Rating | IP65, IP67, optional IP68 hermetically sealed | IP65, IP67 | IP65, IP67 |
| Vibration Resistance | Glycerine or Silicone oil case filling (Liquid Dampened) | Silicone fluid filling | Silicone case filling & internal dampening |
| Electrical Contacts Options | Magnetic snap-action, Inductive (ATEX), Microswitches | Magnetic snap-action contacts | Magnetic snap-action electric switch contacts |
A primary challenge in long-distance remote capillary temperature reading is ambient variation along the capillary line. When ambient temperatures fluctuate along a 20-meter run, fluid expansion inside the capillary can cause reading errors at the dial gauge. Huzhou Accuracy Instrument solves this by incorporating a dual-bimetallic thermal compensation element inside the movement housing. As the ambient temperature rises, the compensating bimetal rotates the movement scale pivot in exact opposition to capillary fluid expansion, ensuring absolute measurement integrity regardless of seasonal or process room ambient shifts.
As global manufacturers seek resilient, cost-effective, high-precision supply chains, Huzhou Accuracy Instrument Co., Ltd. leads the industrial instrumentation sector by integrating Industry 4.0 automation across our 3,000 m² modern production facility.
High-precision robotic fiber-laser welding guarantees hermetic sealing of capillary-to-bulb junctions and Bourdon tube joints, eliminating micro-leaks under high pressure shocks.
Every Rototherm-style capillary system undergoes automated helium leak detection down to $1 \times 10^{-9} \text{ mbar}\cdot\text{l/s}$, ensuring a zero-leak lifespan exceeding 10 years.
Fully automated calibration benches map temperature response curves across multiple thermal baths, laser-engraving custom dial faces to eliminate non-linear scale errors.
From raw SS316 tubing drawing to final dial assembly, internal supply chain integration reduces production lead times by 40% compared to traditional European factories.
Capillary temperature instruments serve as critical safeguards across continuous-duty heavy industries where electronic temperature sensors may fail due to power loss, electromagnetic interference (EMI), or explosive atmosphere risks.
Designed for hazardous Zone 1 and Zone 2 environments. Features ATEX-compliant explosion-proof electric contact switches and NACE MR0175 compliant materials for corrosive $H_2S$ exposure on offshore drilling platforms and refining units.
Specialized temperature-compensated density monitors and capillary instruments for high-voltage power transformers and $SF_6$ gas-insulated switchgear (GIS) ensuring uninterrupted grid stability.
Outfitted with sanitary Tri-Clamp diaphragm seals (3A/FDA compliant), electro-polished surface finishes ($Ra < 0.4\mu m$), and food-grade fill fluids (NEOBEE M-20) for clean-in-place (CIP) steam sterilization processes.
DNV-GL type-approved shockproof and liquid-filled capillary thermometers for diesel engine exhaust gases, turbine cooling loops, and heavy marine refrigeration units subject to violent mechanical vibrations.
Huzhou Accuracy Instrument Co., Ltd. is professionally engaged in the development, manufacturing, and global distribution of industrial mechanical pressure gauges, bi-metal thermometers, capillary thermometers, SF6 manometers, and advanced pressure transmitters.
Established over two decades ago, our state-of-the-art pressure and temperature instrument facility spans 3,000 square meters, equipped with automated production lines, laser welding cells, and ISO/IEC 17025 compliant calibration laboratories.
Our production processes strictly follow the philosophy of "Reasonable Price, Accurate Delivery, Uncompromising Quality" under ISO 9001:2008 certified management systems.
Procurement engineers and sourcing managers must evaluate capillary thermometers against total cost of ownership (TCO), material compliance, and operational risk mitigation. Below is the decision framework established by Huzhou Accuracy Instrument for global buyers.
Mandatory certification for entry into the European Economic Area (EEA). Our thermometers meet Pressure Equipment Directive 2014/68/EU, ensuring structural safety under sudden pressure surges inside thermowells.
Full chemical and mechanical heat number traceability for all wetted parts (AISI 304, 316L, 316Ti, Hastelloy C-276) supplied with official EN 10204 3.1 inspection certificates.
IP67 ingress protection against heavy rain, dust, and washdowns. Glycerine filling (0°C to +60°C) or Silicone fluid filling (-40°C to +100°C) dampens pointer movement under intense process vibration.
Tailored capillary lengths (1m to 50m), bulb outer diameters (6mm, 8mm, 10mm, 12mm), process thread connections (NPT, BSPP, BSPT, Flanged, Sanitary Tri-Clamp), and dual scale dials (°C/°F).
Expert answers to technical procurement, calibration, installation, and application engineering questions regarding capillary thermometers and mechanical instrumentation.
For inert nitrogen gas-actuated systems (Class 1), capillary runs up to 50 meters (164 feet) can maintain Class 1.0 (±1.0% FS) accuracy, provided an internal bimetallic ambient temperature compensator is installed in the case. For liquid-filled systems (Class 5), the maximum recommended length is 15 meters to avoid excessive head pressure and ambient thermal expansion interference.
CE certification verifies that the product satisfies EU safety, health, and environmental protection requirements. Under the Pressure Equipment Directive (PED 2014/68/EU) and EN 13190 standards, CE marking guarantees that the temperature bulb and thermowell system can withstand design pressures and thermal shocks without catastrophic failure or hazardous gas/fluid leakage into the plant environment.
Case liquid filling lubricates the internal rack-and-pinion movement gears, suppressing mechanical wear caused by high system vibration (e.g., adjacent to pumps, compressors, or marine engines). Glycerine is suitable for standard temperatures (0°C to +60°C), while Silicone oil is specified for extreme ambient temperatures (-40°C to +100°C) and applications with electrical contact switches.
Yes. As a direct OEM factory, we manufacture custom stems and thermowells in solid-drilled bar stock or fabricated designs. Standard bulb diameters are 6mm, 8mm, 10mm, and 12mm with insertion lengths tailored from 50mm to 2000mm. Process connection threads include NPT, BSP, metric threads, sanitary Tri-Clamps, or ANSI/DIN flanges.
A bimetal thermometer uses a helical strip of two metals with different expansion coefficients connected directly to a rigid stem pointer shaft, requiring the dial face to be attached directly at the measurement point. A capillary thermometer uses expansion fluid/gas to transmit thermal changes through a flexible, armored tube up to 50 meters away, enabling eye-level remote reading when process ports are mounted high on tanks or hidden inside hazardous machinery.
All Huzhou Accuracy Instrument products come standard with a 12-month factory replacement warranty, 100% pressure cycle testing, helium leak testing verification, and factory calibration certificates according to ISO 9001 quality management procedures.
Browse our comprehensive line of CE-certified pressure sensors, thin-film transducers, vibration-resistant gauges, and SF6 gas density monitors.
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