Hi Enrique
We are going through this with a customer at present and as we are not experts in this field have been researching on the web and this text written by Mark Smith from Multitherm is one of the best we have found:
"A flushing fluid is intended for use in startup or general maintenance of heat transfer fluid systems. New systems may contain mill scale, weld splatter, slag, flux, quench oil, protective coatings, dirt and water. The abrasive contamination can damage pump seals, bearings and control valves. Mill scale and weld splatter can promote fluid oxidation and cracking. The oil, coatings and flux are thermally unstable and can cause fluid degradation. Using a flushing fluid to clear these contaminants out of the system before adding the clean heat transfer fluid will minimize maintenance concerns and help extend fluid life. Flushing fluid also is useful to remove particulate, sludge, some coked-on material and left behind, used heat transfer fluid prior to recharging a system with new heat transfer fluid during a fluid changeout.
Do not use water to clean out an assembled system or to pressure test the system. Instead, use either a flushing fluid, the heat transfer fluid or inert gas. Also, pressurize the fluid with nitrogen rather than air to minimize fluid oxidation.
When filling the system with the flushing fluid, slowly pump the fluid into the system from the bottom up to vent air. Filling from the top (pouring into the expansion tank) hinders air venting and needlessly aerates the fluid. Often, a convenient place to fill the system is through the blowdown connection on the strainer. Use a small positive-displacement pump to transfer the fluid rather than the system pump. "
The link I "stole" this from,
www.multitherm.comEnrique we have no experience with the products on this site so don't take this as an endorsement of their products but the info on the site is useful and assists with understanding,
Regards
Rob S
