TECHNICAL DATA INTRODUCTION

Semco Instruments, Inc. manufactures a wide range of metal sheathed, ceramic insulated wire products under its tradename "SEMPAK®." These products are engineered with physical and electrical characteristics for temperature measurement, resistive heating and electrical cable applications for use where environmental conditions are detrimental to conventional wire and cable.

SEMPAK® is a dense composite of metal sheath and wire which is insulated by a compacted ceramic. It is fabricated from wire, tubing and crushable ceramic preforms in a multitude of sizes, configurations and combinations of insulator materials, wire types and sheath metals.

Environments in which SEMPAK® has proven to be superior:
  • Temperature ranging from near absolute zero to over 4200°F.
  • Liquid metals and nuclear radiation.
  • Acceleration, shock and vibration.
  • Pressure ranging from high vacuum to high pressure - 80,000 psi and above.
SEMPAK® is rugged - it can withstand severe impact. It can be hammered, flattened, bent, welded, clamped, brazed or cast into materials. It comes in a variety of sizes ranging from below 0.010 inch diameter to over 0.500 inch diameter. The sheath can be selected to protect the internal wire from corrosive, moisture, chemical or other environmental attack. It is reliable, flexible and durable.


Table of Contents
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Sheath Materials
  Sheath Material Characteristics
  Table 1 - Properties of Common Sheath Materials
  Table 2 - Other Available Sheath Metals
  Table 3 - Composition of Common Sheath Metals
   
  Figure 1 - Linear Thermal Expansion - Metals
  Figure 2 - Vapor Pressure of Some Selected Materials

Wire Materials
  Wire Material Characteristics
  Table 4 - Limits of Error for Thermocouple Wire
  Table 5 - Manufacturers and Composition of Wire Materials
  Table 6 - Resistance Tables for Solid Thermocouple Wires
  Table 7 - Nuclear and Other Properties of Selected Elements
  Table 8 - Compositional Change of Selected Elements in a Neutron Environment
  Table 9 - Thermocouples Rated for Nuclear Use
  Table 10 - Thermal EMF of Some Selected Thermocouples
  Table 11 - Properties of Thermoelement Materials
  Table 12 - Heater Wire Properties
  Table 13 - High Temperature Wire Properties
  Table 14 - Low Resistance Electrical Wire
   
  Figure 3 - Resistance of Some Selected Thermocouple Wires
  Figure 4 - Thermal EMF as a Function of Temperature
  Figure 5 - Electrical Resistivity as a Function of Temperature for Some Selected Metals
  Figure 6 - Resistance of Some Selected Wires
  Figure 7 - Linear Thermal Expansion - Wire Materials

Insulation
  Insulation Characteristics
Figure 8 - High Temperature Resistivity of Ceramic Insulators
Conversion Tables

Fabrication

Technical Data