This is the fifth in a series of articles outlining the system requirements and considerations when using specialty fluids for product test stands. This issue is the last in this series and will address Low Temperature Testing considerations.
One of the most stringent types of Servo Hydraulic Fluid Testing is high- and low- temperature testing. Some of our customers, and even many of our competitors, have fallen into the troublesome task of designing and building a test system to test at either a high temperature or a low temperature. And even more difficult testing is temperature sweep testing, from ambient to low, to high, and then back to ambient. These tests can be “one-off” to test a product’s reaction to a temperature, or multiple sweep tests, and can continue for many hours or even weeks. Anyone who has applied this type of testing clearly understands that simply raising or lowering the fluid temperature is not the solution to the testing, but the cause of the application problems.
Testing at low temperatures can create many problems in the design and build of a test system. Some key areas for consideration are:
Thermometer 2Test Temperatures – Most of today’s cold fluid testing generally ranges from ambient to -40°F (-40°C), although in recent months the requested temperatures are trending to as low as -61.6°F (-52°C). Fluid temperatures can be varied in a simple stepped test, with several increasing/decreasing temperature points, or as is the more complicated sweeping temperature test, from high to low and back to high, with very specific linear data points to achieve.
Test Fluids – Test fluid can range from many variations of oil, transmission fluid, or any fluid associated with a part’s operation.
Methods of Testing – The method and type of system required to perform cold fluid testing is generally determined by the target test temperatures. While the following test temperature ranges are “base rules of thumb,” each test case should be reviewed for flow, input horsepower (heat), ambient temperatures, length of runs, and part accessibility.
Potential of Injury to Personnel
Additional guarding, interlocked guard doors, and redundant safeties are a must when developing a cold test system. The protection against frostbite, inhalation hazards (if using an inert gas to speed-up temperature swings), and water (ice) build-up reduction should also be taken into consideration when developing a system.
Plain and simple, fluid power components do not react the same when operating at cold temperatures as they do at their -100°F (-37.7°C) rated temperatures. Component selection must include consideration of the fluid viscosity at the test temperature, the type of seals and materials, rated component flows and leakages, and component life/warranties.
Other designed and operational requirements which must be taken into consideration include:
Wineman Technology has proven experience with all types of temperature testing to suit all of your applications. To avoid the pitfalls of cold fluid testing, rely on us for all of your temperature test system’s needs. For more information on please contact Wineman Technology today.