Explosion proof thermocouple with fixed flange

Explosion proof thermocouple with fixed flange

Overview of Explosion proof thermocouple with fixed flange

Explosion proof thermocouple with fixed flange is a kind of temperature sensor, which is widely used in the automatic control system of chemical industry. Through the temperature sensor, the temperature parameters of the control object can be transformed into electrical signals and transmitted to the display, recording and regulating instruments to detect, adjust and control the system. In chemical plants, the production site is often accompanied by various flammable, explosive and other chemical gases and vapors. If ordinary thermocouples are used, it is very unsafe and it is very easy to cause ambient gas explosion. Therefore, Explosion proof thermocouple with fixed flange must be used as temperature sensors in these occasions. Explosion proof thermocouple with fixed flange produced by Jiangsu Xunfei are suitable for places with explosive gas hazards in the temperature group range of D Ⅱ BT4 ~ d Ⅱ CT6, IB Ⅱ BT4, IA Ⅱ BT4 and IA Ⅱ CT6.

Technical data of Explosion proof thermocouple with fixed flange
Explosion proof thermocouple with fixed flange shall comply with JB / t9238-1999 technical conditions for industrial thermocouples and GB / t16839 1-1997、GB/T16839. 2-1997 industrial thermocouple graduation table and allowable error, and the products meet the general requirements of explosion-proof electrical equipment for explosive environment GB3836 1-2000、GB3836. 2-2000 standard, the national instrument explosion-proof safety supervision and inspection station shall specially examine and approve the product drawings, technical documents and prototypes, and issue explosion-proof certificates.

At present,Explosion proof thermocouple with fixed flange produced by Jiangsu Xunfei include nickel chromium nickel silicon (type K) and nickel chromium copper nickel (type E). Intrinsically safe thermocouple must use intrinsically safe compensation wire, and its distribution parameter control range: total inductance ≤ 2mh, capacitance ≤ 0.06 μ f. At the same time, the safety barrier of associated equipment shall be used. The selection of associated equipment shall follow the following principles. When the thermocouple (must be insulated) is equipped with low internal resistance secondary instrument, mtl75 / acz605 / ex and lb95 / AC shall be selected, and when the secondary instrument with high internal resistance is equipped, mtl760 / AC, z960 / AC and lb960 / AC safety barrier shall be selected. See the manufacturer's instructions for the specific wiring of safety barrier.

Main technical parameters of fixed flange explosion-proof thermocouple
◆ measurement range: 0-800 ℃, 0-1100 ℃,0~1000℃,0~350℃,0~600℃
◆ graduation number: K,E,N,T,J graduation
◆ accuracy grade: Grade I (± 1.5 ℃ or ± 0.004 t ｜) grade II (± 2.5 ℃ or ± 0.0075 t ｜)
◆ thermocouple category: nickel chromium nickel silicon
◆ material of protective tube: stainless steel (304 or 321)
◆ thermal response time: t0 5 ≤ 90s (when there is a step change in temperature, the time required for the output of the thermocouple to change to 50% of the step change is called the thermal response time, represented by t0.5).
◆ nominal pressure: generally refers to the static external pressure that the protective pipe can withstand without rupture at room temperature. The test pressure is generally 1.5 times of the nominal pressure. In fact, the allowable nominal pressure is not only related to the material, diameter and wall thickness of the protective pipe, but also related to its structural form, installation method, placement depth and the flow rate and type of the measured medium.
◆ thermocouple insulation resistance: the test voltage of insulation resistance at room temperature is DC 500 ± 50V. The atmospheric conditions for measuring insulation resistance at normal temperature are: temperature 15 ~ 35 ℃, relative humidity 45%, atmospheric pressure 86-106kpa.
For thermocouples with a length of more than 1m, the product of its normal temperature insulation resistance and its length shall not be less than 100m Ω m。

For thermocouple with length equal to or less than 1m, its insulation resistance at room temperature shall not be less than 100m Ω.
◆ insulation resistance of armored thermocouple (insulation type): when the ambient temperature is 20 ± 15 ℃ and the relative humidity is not more than 80%, the insulation resistance between the Thermoelectrode and the outer sleeve shall be greater than or equal to 100m Ω M (i.e. the product of insulation resistance at normal temperature and the length of armored thermocouple), and the test voltage is DC 500V.
◆ explosion proof type and class group
Explosion proof group: D Ⅱ BT4 or D Ⅱ cT4; D Ⅱ BT6 or D Ⅱ CT6
Intrinsically safe group: IA Ⅱ BT4 or IA Ⅱ cT4 (multi pair); IA Ⅱ BT6 or IA Ⅱ CT6 (multi pair)
◆ enclosure protection grade: IP65
◆ description of explosion-proof sign, category, level and temperature group:

Explosion proof sign: flameproof type (d); Intrinsically safe (IA)
Electrical equipment category: class I - electrical equipment for underground coal mine; Class II - plant electrical equipment
Explosion proof level: the explosion-proof level of explosion-proof intrinsically safe thermocouple is applicable to explosive gas mixture. The maximum safety gap or minimum ignition current score is level a, B, C and III.
◆ temperature group: the temperature groups of flameproof and intrinsically safe thermocouples are divided into six groups: T1 ~ T6 (T1 = 450 ℃, T2 = 300 ℃, T3 = 200 ℃, T4 = 135 ℃, T5 = 100 ℃, T6 = 85 ℃) according to the maximum allowable surface temperature of their exposed parts.

Principle and structure of flameproof and intrinsically safe thermocouples
The structure and principle of flameproof or intrinsically safe thermocouples are basically the same as those of assembled thermocouples. The difference is that the junction box (shell) of flameproof or intrinsically safe products adopts explosion-proof special structure in design. The junction box is made of high-strength aluminum alloy by die casting, and has sufficient internal space, wall thickness and mechanical strength. The thermal stability of rubber sealing ring meets the national explosion-proof standard. Therefore, when the explosive mixed gas inside the junction box explodes, its internal pressure will not damage the junction box, and the resulting heat energy cannot diffuse outward to spread explosion. Because the product adopts the above explosion-proof special structure, the product fully meets the explosion-proof category of D Ⅱ BT4 to D Ⅱ CT6, ibiibt4, iaiibt4 and iaiict6. As long as the user strictly abides by the product use rules, the product can achieve reliable explosion-proof effect.

Model table of Explosion proof thermocouple with fixed flange