Tank blanketing systems maintain a slight (0.5" WC) minimum positive pressure of an inert gas within the vapor space of an enclosed vessel. As most atmospheric storage tanks are only rated at approximately 2" WC an accurate and reliable maintenance of the minimum pressure is essential to keep the tank from forming a vacuum internally due to stock pump-out or ambient cooling effects.
For over 20 years Appalachian Controls provided "piped up" tank blanketing systems, through their 78, 79, 80 and 90 Series systems, to the chemical, pharmaceutical, food and computer industries. These systems were designed to be simple, accurate and extremely rugged with minimum life spans of 5-15 years. Using gas field production regulators and wide tolerances, these regulators stood up to heat, cold, dirt and generally rough environmental conditions for years with little or no maintenance.
Several years ago Appalachian Controls obsoleted these "piped up" tank blanketing systems in favor of a newer piston/diaphragm design that has its roots in the Anderson Greenwood blanketing regulator of many years ago. In the past year Fisher has bought Appalachian Controls Environmental (ACE) and are no longer supplying the technical assistance, parts or replacement tank blanketing systems that had brought Appalachian Controls to the forefront of tank blanketing applications. There are literally thousands of the older "piped up" Series 78, 79, 80 and 90 Tank Blanketing Systems still in service around the world and no one to go to for information, replacement parts or new systems.
As a former employee of Appalachian Controls and with a great love and respect for these older systems, I would be interested to help anyone who has one of these "piped up" tank blanketing systems and has a need for technical information, parts or replacement systems. If you have an existing system, please let us know the model number and serial number that is stamped on the tag riveted to the cross bar. The model number identifies the Series and options included on the system. The serial number is a date code: xx(year), xxx(Julian day of the year), x sequential number of units produced that day). Inlet nitrogen pressure, required flow rate (SCFH nitrogen), system set point and tank relief vent settings are also required for replacement systems.