Nutech Engineers
143-D Government Industrial Estate, Kandivli West, Mumbai - 400 067
Phone : 91-22-28683549 / 28684580,  Fax : 91-22-28674580
email : nutechen@vsnl.com , nutechen@mtnl.net.in,
info@nutechengineers.com,  sales@nutechengineers.com

Temperature Sensing Devices

MgO

Thermocouples with Magnesium Oxide (MgO) insulation have a high dielectric strength, respond quickly to temperature changes.

Magnesium oxide insulated thermocouple wire is manufactured from premium quality wire incased in magnesium oxide and processed into a chemically clean outer metal sheath.  The wires are individually selected and matched and are of uniform cross section with smooth surfaces.  Finished stock is warranted to meet ANSI Standard Limits of Error set forth in MC 96.1.  The unique preparation of magnesium oxide insulated thermocouple wire produces a uniform thickness of insulation with high density.  The result is a product that is mechanically strong and resistant to penetration of corrosive gases and moisture.  MgO is densely packed, of 99.4% purity or better.

Thermocouple Calibration

• Iron-Constantan
• Chromel-Alumel
• Chromel-Constantan
• Copper-Constantan

Element Sheath Diameter

• .125" (1/8") Outside Diameter
• .188" (3/16") Outside Diameter
• .250" (1/4") Outside Diameter

Element Sheath Material

• 304 Stainless Steel
• Inconel 600
• 316 Stainless Steel
• 310 Stainless Steel

Spring loading is designed to maintain tip contact to the end of the thermowell for best heat transfer.

Junction Construction

Single Element Grounded  Thermocouple welded to the sheath.  Fast Response with thermocouple protected, either single or dual.

Ungrounded (Insulated) Thermocouple insulated from sheath with magnesium oxide.  Stray EMF's are prevented from affecting the reading.  Response from rapid or frequent temperature cycling is slower than for grounded style.

Dual Element Common  Two thermocouples with junctions welded, either to sheath or insulated.

Dual Element Ungrounded Isolated Two thermocouples electrically separate in the same sheath, provides isolation where instrumentation necessitates.

TIME CONSTANTS

The time constant is the time required for a thermocouple to indicate 63.2% of a step change in temperature in a surrounding media.  Some of the factors influencing the measured time constant are sheath wall thickness, degree of insulation compaction, and distance of junction from the welded cap on the ungrounded style.  In addition, the velocity of liquid or mass velocity of a gas past the thermocouple probe greatly influences the time constant measurement.  In general, time constants for measurement in a gas can be estimated to be 10 times as long as those for measurement in a liquid.  The time constant also varies inversely proportional to the square root of the velocity of the media.