What are the standards for fixed flange mounted junction box type platinum resistance thermometers

To make sure that fixed flange mounted junction box type platinum resistance thermometers are accurate, safe, and can be used in many industrial temperature measuring situations, they are designed and made according to several national and international standards. These standards include things like electrical performance, structural dimensions, material requirements, installation specifications, and explosion-proof features. This sort of sensor is based on the following fundamental standard system:




I. Core Temperature Measurement Standards: Making Sure They Are Correct and Reliable



The International Electrotechnical Commission (IEC) released IEC 60751:2022, which sets the resistance-temperature relationship, tolerance grades (Grade A: ±(0.15 + 0.002|t|), and test methods for Pt100 and Pt1000.Grade B: ±(0.30 + 0.005|t|)℃; test methods for Pt100 and Pt1000. It is a technological standard that is known all over the world.



GB/T 30121-2013 "Industrial Platinum Resistance Thermometers and Sensing Elements" is a Chinese national standard that is similar to IEC 60751. It explains the technical specifications, inspection standards, and marking and packaging for industrial platinum resistance thermometers. It is true for all platinum resistance thermometer products that have been put together.



JB/T 8622-1997 "Technical Conditions for Industrial Platinum Resistance Thermometers" is a standard for the mechanical industry that lists things like the sensing element's structure, insulation performance, and thermal response time. It also goes into great detail about how junction boxes, protective tubes, and fixed flanges should fit together.







II. Standards for structure and installation: Making mechanical interfaces the same



Standards for Flange Connections



HG/T 20592–20635-2009: A standard for flanges in the chemical industry that lists the sizes, pressure ratings (PN1.6–PN4.0MPa), and sealing surface shapes of flanges with DN15–DN2000. A lot of people use it to construct the connections for fixed flange-type resistance thermometers. ANSI B16.5 / DIN 2501: This standard is for equipment that is shipped out of the country or for projects that involve more than one country. It makes sure that the piping systems in the US and Europe will work with the equipment.



Structure of the Protective Tube and Junction Box



JB/T 5582-91 "Protective Tubes for Thermocouples": This standard is specifically for thermocouples, however the ways it tests the pressure and corrosion resistance of stainless steel protective tubes (such 316L and 904L) are also utilized in the platinum resistance thermometer industry.



IP Protection Rating (GB/T 4208): To keep moisture and dust out, junction boxes must have an IP54 (splash-proof) or IP65 (waterproof) rating.







III. Standards for Special Operating Conditions: How to Deal with Extreme Environments



Standards for protecting against corrosion



An integral sintered polytetrafluoroethylene (PTFE) anti-corrosion layer is utilized in extremely corrosive conditions. To make sure there are no pinhole faults, it must pass 12kV electric spark micro-hole flaw detection.



The thickness of the anti-corrosion coating is usually 1.0mm, but it can be changed to fit your needs. It also meets safety standards for chemical processes.



Standards for Explosion-Proof



GB 3836.1-2010 and GB 3836.2-2010: These standards apply to places where there are explosive gases (like dⅡBT4 and dⅡCT6 groups). The junction box must be explosion-proof and able to handle explosions from inside without spreading.



"WZP-441" and other similar numbers are widely used to denote explosion-proof products. The junction box is composed of a strong aluminum alloy that has been die-cast. It has an IP65 protection level.







IV. Electrical and Safety Standards: Making sure the system stays stable



Requirements for insulation resistance



The insulation resistance between the electrode and the outer sheath should be at least 100MΩ (DC 10–100V) in an environment with a temperature of 15–35°C and a relative humidity of 80% or less. The copper resistance should be at least 50MΩ.



Standards for Wiring Methods



A three-wire connection approach is often used to get rid of the effect of lead resistance on measurement accuracy and to meet the input needs of automated control systems. Nominal Pressure and Strength of Materials



The fixed flange type structure can handle larger pressures, with a maximum operating pressure of 4.0 MPa (flange mounting) or 0.6 MPa (threaded mounting). The test pressure is 1.5 times the normal pressure.







V. Standard Correspondence and Typical Model



Table Model Example Standard Basis Description



WZP-430 JB/T 8622-1997 Fixed flange connection, waterproof junction box, type Pt100



WZP-441 GB 3836.1/2 is an explosion-proof kind that can be used in situations where chemical explosions are likely to happen.



WZC-430-F JB/T 8623-1997 Cu50 copper resistor with a coating that protects it from rust. It has a fixed flange type.



When buying or designing something, the standard code that should be followed should be clearly stated, such "compliant with IEC 60751 Class B, flange according to HG/T 20592 DN25 PN1.6." This will make sure that the product can be used with other products and that the system will work with it.