Many fire suppression systems used in condominiums are designed for use with a mix of water and anti-freeze. It is critical that the correct anti-freeze be used to fill the system. The National Fire Protection Association (NFPA) Code governs fire suppression systems and prohibits the use of glycols as anti-freeze in listed fire suppression sprinklers and fittings. NFPA section A-4-5.2 requires that only glycerin anti-freeze be used in such systems. Manufacturers of the pipes used in such systems also require that only glycerin be used because some glycols–such as ethylene glycol–can cause chemical breakdown of the pipes. Over time, microscopic cracks will begin to develop inside the pipes that will eventually lead to leaks or catastrophic failures.
Some engineers will opine that even though the use of glycols is banned by the NFPA, a 50% glycol solution can be used because the plastic pipes are chemically rated to handle the stresses caused by use of glycols. However, you should have an experienced engineer check with the manufacturer of the pipes in any such system and with the manufacturer of the other components in such a system because they will likely void their warranties if glycols are used rather than glycerin.
Recently, the Summer Hill Condominium Association in Delran settled a case for $4.5 million in which glycols were used in fire suppression systems that were designed to be filled with a 50% glycerin solution.