Purchasing personnel often need to confirm the matching relationship between the heating rod and the bolt center hole. It is recommended to first measure the diameter and depth of the bolt center hole, then compare them with the product's sleeve outer diameter and heating length. Taking the DJR-22A series, which fits a center hole diameter of 22.6±0.2mm, as an example, the sleeve outer diameter should be slightly smaller than the hole diameter to ensure smooth insertion and leave clearance for thermal expansion.
The DJR-22A series offers multiple specifications. DJR-22A-1 is suitable for M56×4 bolts, with a sleeve length of 255mm, a heating length of 100mm, and a power of 550W; DJR-22A-6 is suitable for M56×4, with a sleeve length of 405mm, a heating length of 250mm, and a power of 1400W; DJR-22A-7 is suitable for M76×4, with a sleeve length of 315mm, a heating length of 125mm, and a power of 900W; DJR-22A-13 is suitable for M76×4, with a sleeve length of 540mm, a heating length of 350mm, and a power of 2350W. When selecting, it is necessary to consider the bolt specification, heating depth, and power requirements.
Surface load (watt density) is a key parameter in selection. In liquid heating scenarios, the surface load is usually controlled between 1.5W/cm² and 3W/cm². Exceeding this range may cause the heating wire temperature to be too high and shorten the service life. During procurement, the actual surface load value should be confirmed with the supplier to avoid early failure caused by excessive power density.
The heating wire of the DJR-22A series uses 0Cr27A17Mo2 high-resistance electric heating alloy wire, with an operating temperature of 400°C; the protective sleeve is a 1Cr18Ni9Ti heat-resistant stainless steel tube; the insulation material is standard-compliant dried magnesium oxide powder. This combination can adapt to the long-term operation needs of industrial high-temperature and dusty environments. During procurement, suppliers can be asked to provide material certificates to ensure compliance with the ZBK54019-88 industry standard.
