16A
ANALYTICAL
CHEMISTRY
How to Eliminate "Cold-End" Errors
Use C h r o m e l - A l u m e l Extension
Leads
w i t h your C h r o m e l - A l u m e l jVJpdern pyrometers, within themselves, leave little to be desired as far as accuracy of temperature measurement is concerned. They're precision built instruments . . . delicately balanced . . . equipped with automatic cold-end compensators . . . de signed and engineered throughout to give you the fine degree of accuracy you need. And, o n 3 out of every 4 heat treating installations, these accurate meters are calibrated for CHROMELALUMEL thermocouples . . . durable, dependable, sensitive couples unconditionally guaranteed to register true temperature—E.M.F. values within extremely close specified limits. Yet, in spite of all the fine accuracy built into these meters a n d couples, uncontrollable "cold-end" errors will frequently occur when so-called "com pensating" lead wires are used. Here's why . . . As you know, when wires of different composition
Thermocouples
are joined together, they form a thermo-electric junction. I n the case of "compensating" leads connected to your Chromel-Alumel couples, these junctions are located just outside the furnace and unprotected from heat. Now, as these terminals get hot . . . and they often get very hot... or when one junction gets hotter than the other, the opposing E.M.F.'s they generate tend to become more and more unequal. And this variable in equality is inevitably reflected by serious plus or minus errors registered by your meter. H o w to eliminate this common cause of "cold-end" errors? Simple! Use C H R O M E L - A L U M E L EXTENSION LEADS with your CHROMEL-ALU MEL thermocouples. For only by using these wires of identical composition can you be sure of getting the full benefits of accuracy offered by today's improved pyrometers. Our Catalog 59-R tells the complete technical s t o r y . . . want a copy?
CHROMEL-ALUMEL couples and leads are available through your instru ment manufacturer or pyrometer service company . . . ask for them by name!
HOSKINS MANUFACTURING 4 4 4 5 N E W
LA W Τ Ο Ν YORK
A V E .
·
CLEVELAND
D E T R O I T ·
COMPANY 8,
M I C H I G A N
CHICAGO
West Coast Representatives in Seattle, San Francisco, Los Angeles In Canada: Walker Metal Products, Ltd., Walkerville, Ontario
ckel-chromium
resistance alloy that first made electrical heating
practical
