Thursday, August 18, 2011

Biofouling–A life of its own.

Is your system ready to take on a new life? Many technology solutions require clean water for their process. In the semiconductor industry, ultra-high purity water is a must with extreme deionization of water. Residential water heaters even have problems with scaling, and many of the high-efficiency tankless systems cannot be installed in areas with hard water.

Scaling issues with calcium and magnesium are commonly on the mind of a system developer maybe because it is something we experience everyday. On the other hand, biofouling is not always considered until it is too late. Much like scaling, once biofouling starts it may be impossible to treat, control or recover from the growth.

In system testing, it is common to set specifications for the end user and test for the environment that is readily available. Water quality around the world is not equal.

Crazy_Red_BugA Tale of Two Microbes

A problem was experienced when multiple systems tested in the Boston Massachusetts area over several years had no indication of problems with water except for hardness, which was treated with standard filtration and ion exchange materials. A major market was a well developed European country. The problem started with system overheating that required a tweak to the cooling pump curves every few months to keep the system operational. When a shutdown occurred and the system

Tuesday, August 16, 2011

Process Temperature Sensitivity

Temperature sensitivity of processes should be considered early in the design before specifying equipment. Frequently, designers specify a single thermal measurement device for ease of use, replacement, and inventory. Not a bad idea if all temperaturTemperature_Displayes are near the same range or the process is not sensitive. K-Type thermocouples are very popular due to their wide range of temperatures (-200˚C to 1250˚C), but when measuring high temps of 1000˚C and water temperatures around 50˚C what is the error associated with them?

Many designers do not realize that an error even exists and even process interfaces and data files will be set up with one or two decimal places. The standard error of a K-Type thermocouple is a minimum of 2.2˚C and at temperatures nearing 1000˚C the error nears 7˚C. So with even a 4.4 degree spread on error, reading temperatures in tenths of a degree is useless, requires more data-storage  space and adds irrelevant