THE UNIQUE PROPERTIES of U Type Moly-D Heaters
- U Type MOLY-D elements may be used up to a surface temperature of 1800 °C(3270 °F) in oxidizing atmospheres.
- Long service life and ease of replacement contribute to high furnace utilization and low maintenance costs.
- New and old elements can be use together and in series.
- Can dissipate high power loading.
- Can be use continuously or intermittently.
- Provide rapid furnace temperature ramping.
- Maximum Element Temperature —
1700 °C(3090 °F)- General Applications — Most types of industrial furnaces for heat treating, forging, sintering, glass melting and refining, and for use in radiant tubes.
- Maximum Element Temperature —
1800 °C(3270 °F)- General Applications — Laboratory furnaces,testing equipment,and high temperature sintering production furnaces.
U Type MOLY-D(Molybdenum Disilicide Heating Element) heating elements are manufactured by powder metallurgy. They consist of molybdenum disilicide with additives that prevent recrystallization. Since U Type MOLY-D is completely stable up to 1800 °C, it surpasses other heating element types for high temperature performance.The resistance of U Type MOLY-D to oxidation lies in the formation of an impermeable quartz, or glass-like protective layer which re-forms when heated if damaged in operation.has a low specific electrical resistivity with a positive resistance-temperature characteristic as shown in figure 1.
It can be used at a very high watt loading compared to metallic heating elements.
Please refer to figure 2, for watt loading at various element temperatures. Because of its high temperature oxidation resistance, U Type MOLY-D electrical resistance remains constant at constant temperature over its useful life. This permits the use of old and new elements together in the same furnace, even if series-connected.
Figure 1, Resistivity of U Type MOLY-D elements EQ-1700 and EQ-1800
Figure 2, Recommended surface loads for
U Type MOLY-D heaters
SERVICE LIFE & EXCHANGE
* The resistance of U Type MOLY-D heating elements are not aged.
Main reason of uncontributed life service is tha mechanical breakage, when they are cooler in short time or sometimes power of electromagnetic.* It is possible to exchange elements during operating.
This element is not aged. Please exchange only broken elements. This is our recommended characteristic and advantageous to U Type MOLY-D heating elements.
As shown in Table A,below,maximum element temperature depends on the atmosphere within the furnace chamber. In air this is 1800 degrees centigrade.
Since element surface temperature exceeds furnace ambient in relation to the watt loading, careful attention must be given to these parameters for satisfactory element performance. U Type MOLY-D heating elements normally operate between 1300 and 1750 Cent. (2372-3182 Fahr.). U Type MOLY-D may be used below 1300 Cent. (2372 Fahr.) particularly for furnace atmospheres harmful to silicon carbide heating elements (e.g., sulfur dioxide, water-steam,etc.).
U Type MOLY-D should not be used between the temperature range of 400 and 700 Cent.(752-1292 Fahr.), where a destructive low temperature oxidation may occur called pest.
MOLY-D heating elements are designed for use in oxidizing atmospheres. In addition, neutral atmospheres such as nitrogen, inert gases, CO and CO2 are not harmful to MOLY-D. Maximum element surface temperatures in various gaseous enbironment are given following.
Atmospheres EQ1700 EQ1800 MR1800 EQ1850 Air 1700 1800 1800 1850 Nitrogen 1600 1700 1700 1750 Argon, Helium 1600 1700 1700 1750 Dry Hydrogen, dewpoint -80°C 1150 1150 1150 1200 Moist Hydrogen, dewpoint 20°C 1450 1450 1450 1500 Mixed Gas(e.g. 10% CO25% CO15% H2) 1600 1700 1700 1750 Mixed Gas(e.g. 40%H2, 20%CO) 1400 1450 1450 1500 (8% H2)Cracked and partially burnt ammonia 1400 1450 1450 1500