WZP Series Flameproof Thermal Resistors

Industrial explosion-proof platinum resistance thermometers are temperature sensors. Widely used in industrial automatic control systems, they convert the temperature parameters of the controlled object into electrical signals, which are transmitted to display, recording, and regulating instruments for system monitoring, adjustment, and control. In chemical plants and production sites, flammable and explosive gases and vapors are often present; using ordinary platinum resistance thermometers under such conditions is highly unsafe and can easily trigger an explosion of the surrounding atmosphere. Therefore, explosion-proof thermocouples must be employed as temperature sensors in these environments. Our factory’s explosion-proof platinum resistance products are suitable for use in hazardous areas classified as temperature groups d II BT4 to d II CT6, where explosive gases are present. The explosion-proof thermocouples manufactured by our company utilize imported sensing elements, with technical performance compliant with the ZBY301-85 industrial platinum resistance specifications and calibration tables.Furthermore, the product complies with the general requirements for explosion-proof electrical equipment used in explosive atmospheres as specified in GB 3836.1-83 and GB 3836.2-83.

◆ Main Technical Specifications
 Measurement Range Specifications

Note: “t” represents the measured temperature of the temperature-sensing element; dual-platinum resistance sensors are supplied only in Class B
 Permissible current for thermal resistors
 The maximum measurement current through the platinum resistor shall not exceed 5 mA.
   
 Explosion-proof Type and Class
 Explosion-proof category: d II BT4 or d II CT4; d II BT6 or d II CT6
 Enclosure protection rating: IP54

    Principle and Structure
 The structure and operating principle of flameproof resistance thermometers and assembled resistance thermometers are essentially the same; the key difference is that the junction box (housing) of flameproof models is designed with a special explosion-proof structure. The junction box is die-cast from high-strength aluminum alloy and features sufficient internal space, wall thickness, and mechanical strength, while the thermal stability of the rubber sealing ring complies with national explosion-proof standards. Consequently, when an explosive gas mixture inside the junction box ignites, the resulting internal pressure cannot rupture the enclosure, and the heat generated cannot propagate outward—thus preventing flame transmission.
 Due to the product's aforementioned explosion-proof special structure, it fully complies with use within the d II BT4 to d II CT6 explosion-proof temperature class range. As long as users strictly adhere to the product's operating instructions, the product can achieve reliable explosion-proof performance.
  

Explanation of the categories, classes, and temperature classes of electrical equipment:
 Electrical equipment is divided into two categories: Class I—electrical equipment for use in coal mine underground;
 Class II—electrical equipment for use in factories
   
 Explosion-proof rating
 The explosion-proof rating of flameproof thermal resistors is standardized and applies to explosive gas mixtures; the large clearance is classified into three levels: A, B, and C.
 

Temperature Class
 The temperature class of the internal resistance in explosion-proof enclosures is divided into six groups, T1 to T6, based on the maximum surface temperature of its exposed parts.
 

Types and Specifications of Flameproof Thermal Resistors

FlameproofArmoredThermocouple Types and Specifications