Made to standard specifications for ASTM. Made in accordance with the National Institute of Standards and Testing specifications. Most of these thermometers are made of yellow back wide bore tubing that is properly aged and selected for uniform bore. Shaped to be pointed and then calibrated with great care to assure accuracy. Annealed to release stresses and thus reduce breakage. Has permanent fused pigment in the scale where permitted by design. Easy to read numbers for easier interpolation from fine reading graduations. Contains an expansion chamber for over range protection and is filled with inert gas under pressure to reduce column separation. Comes with heavy transparent plastic tube. Certified by the W. L. Walker Company Lab.
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