I have had a ammonia / glycol plate heat exchanger fail internally resulting in the contamination of the full glycol charge. The system has been drained, flushed and a new glycol charge added (approximately 23k ltrs) but due to the allowable system downtime when the new glycol has been charged back into the system and circulated there is still traces of ammonia pressent in the sampled glycol. The system pipe work is stainless steel but the evaporator coils and control valves are copper / brass.

My Questions

Is there anything that can be used to neutralize the affects of NH3 in the water / glycol mix or a recommended allowable level of NH3 in the mix that will not result in the corrosion of the copper and brass that is in the glycol system. Also can anyone recommend a test that can be used to check the NH3 concentration pressent in the water / glycol mix.