The Coolant Service Monitoring System (CSMS) was designed to solve the mystery of knowing when to service the coolant in an automobile's cooling system. However, seeing how it could be applied to any engine that required coolant in the form of water and any type of anti-freeze, it would benefit a large amount of people. The guesswork involved in knowing to service the coolant would be reduced to an indicator in your instrument panel lighting up; notifying the operator that the coolant required replacement or servicing.
The Coolant Service Monitoring System (CSMS) is a two-stage device. It measures the pH (−log [H+] or the measurement of the concentration of the H+ ions) and the voltage drop between the coolant and common electrical ground. With engine cooling systems, a certain pH level would indicate the coolant is ready to be serviced and/or replaced. In addition, a high voltage reading (varies depending on radiator construction and coolant material) would indicate an advanced level of electrolysis. These readings would be processed through simple gauges or indicators notifying the operator if coolant service is required. The actual pH and voltage “critical” values vary depending on the material of the radiator as well as the additive package used in anti-freezes and coolants.
The Coolant Service Monitoring System (CSMS) is expected to be a low-cost coolant indicator system, so it is expected that the CSMS will employ inexpensive gauges or indicators that notify the operator of the engine if the coolant requires servicing.
The CSMS uses both a pH probe and a voltage sensor to take periodic readings of the engine coolant to determine if the coolant requires servicing. Since there are different radiator designs and coolant additive packages developed by various engine and automotive manufacturers, it is impossible to pinpoint exact critical pH and voltage readings. This is best left to the engine and automotive manufacturers.
The CSMS sensors are installed in areas of the engine that see a high volume of coolant flow in order to get the most updated readings available. The coolant pH and voltage is best sampled when the coolant is circulating.
The CSMS pH sensor is powered by any standard voltage source. In an automotive application, it may be preferred to directly use a +12V DC source such as the one from the car electrical system. The CSMS would take readings of the coolant and if the pH or voltage exceeds a pre-determined level (established by the engine or automotive manufacturer), the indicator or gauge will notify the operator that the coolant requires servicing.
In a standard ethylene glycol and water coolant system, a voltage above 0.4V DC requires attention because this indicates an advanced level of electrolysis and can accelerate corrosion of metal cooling containers. In a standard ethylene glycol and water coolant system, a pH lower than 8 demands immediate attention.
As a comparison, a fresh mixture of 50/50 ethylene glycol-based antifreeze and distilled water will show a voltage reading of 20 mV DC (with respect to common ground) or lower, while the pH will read 10.5 or higher.
The CSMS would take readings of the voltage and pH. If it reaches a critical value, such as a pH of 8.0 and a voltage of 0.25V DC, the indicator gauges or lights will then notify the operator that a coolant change is required or to service their vehicle at the nearest authorized dealership.