"What are the parameters to be tested/ monitored for engine coolant/antifreeze? I read somewhere that chloride content should not surpass 50 parts per million. Do you have any other suggestions for trace metals, etc.?"
The cooling system of a machine is a critical component, as it impacts the overall efficiency and operating parameters of the rest of the machine. Consider the radiator in your car. It does a variety of things for the system as a whole. Not only does it cool the engine, and in some cases the transmission, but it also can be used in the heating system during winter.
When it comes to antifreeze or coolants, many of the same principles that apply to lubricants hold true. They should be monitored and taken care of in order to get the most out of them. A typical coolant test will check for contaminants, water content and metals that could indicate potential problems inside the cooler or radiator.
Many laboratories that test lubricants also test coolants. Certain tests are used to examine properties such as pH and additive levels. Similar to lubricant analysis, the goal in coolant analysis is to monitor the health of the coolant as well as the health of the overall cooling system.
Chlorides in a coolant can lead to corrosion inside the cooling system. However, it would be difficult to set a maximum value for all coolants, as these levels can change based upon the type of coolant being used and how the system operates.
Monitoring the coolant’s additive health is very important. Additives help improve the characteristics of the coolant by reducing the corrosive nature of the fluid. Most of these additives anchor themselves to the metals in the cooling system and build up a film to help reduce any corrosion due to water or acids in the coolant. As with any fluid containing additives, the health of these molecules becomes essential to ensure that the system operates as efficiently and as effectively as possible.
As you can see, there are many variables to consider when performing coolant analysis. A number of laboratories offer this type of analysis as part of their standard package, but trending the data is an absolute must. Samples should be taken routinely and in a consistent manner to ensure that the data coming from the lab is trendable and that reports can be used to create a plan of action.