Circulation Heaters Used in Thermal Shock Tests of Glass Bottles

Circulation Heater

The Challenge
For accurate results, maintaining the temperature of hot water, used in thermal shock tests, at a constant temperature of 90° F above incoming cold water. The cold water varies from 50° F to 80° F. From the daily production of over one-half million bottles, spot-checks are made by immersing first in hot water for five minutes and then immersing in cold water. Tests determine durability of bottles and their ability to withstand sudden temperature changes.

The Solution
After thorough evaluation of the system, two 12 kW Chromalox circulation heaters were installed. Water is pumped constantly through the heaters and the built-in thermostats automatically control the heaters to maintain the preset temperature. The operator merely sets the thermostat to maintain the differential of 90° F between hot and cold water. In this way, accurate temperature control is assured for each successive test.


  • Assures accurate temperature control necessary for dependable thermal tests.
  • No wasted heat - all the heat goes into the water.
  • Compact heaters are easily installed at job site.
  • Low original cost - heaters are furnished complete with insulation and built-in thermostat.