| For as long as engines have existed there has been a | | | | the float switch device and even the cost is not too |
| need to ensure that they run at the optimum | | | | dissimilar. The reliability of electronic coolant level |
| temperature and that coolant is always and freely | | | | sensors is without parallel and they are an automatic |
| available. The two main types of coolant are either | | | | choice for many engine manufacturers. |
| air or water based liquids both of which operate by | | | | The capacitive switch uses exactly the same |
| being circulated around the engine to prevent it from | | | | technology as the capacitive sensor, but uses |
| overheating. | | | | capacitance to provide a "switching condition" on |
| For many years, the monitoring of coolant levels was | | | | contact with liquid rather than a continuous |
| never carried out or if it was, then at best a cursory | | | | measurement dependent upon liquid level. The |
| dipstick was used. During those days, engines were | | | | principle of the liquid level switch is very simple and |
| much larger and comparatively inefficient so a slight | | | | the ways of achieving it are very diverse and use a |
| loss of coolant did not present so much of a | | | | wide range of different technologies, but modern |
| problem, but as engine design has evolved over the | | | | capacitive switches such as Fozmula's S85/86 Range, |
| years and newer lighter materials came into use then | | | | have their own embedded microprocessor, enabling |
| the repair or replacement costs of engines damaged | | | | them to be programmed to accommodate a wide |
| by a catastrophic loss of coolant meant that the | | | | range of switching options, whether in coolants, oils |
| presence of coolant was essential and that there | | | | or fuels. |
| needed to be an alarm if the coolant fell below a | | | | Now a level switch cannot only provide an alert to |
| determined level. | | | | indicate that a coolant level has fallen below a |
| Frequently used these days is a small single point | | | | pre-determined minimum, but it can also, without a |
| float switch which can make or break when the | | | | relay, shut down an engine before irreparable damage |
| coolant level falls below a certain level. These devices | | | | occurs. Also a wide range of different voltage |
| are cheap, easy to fit and tolerably effective. They | | | | outputs can be chosen so that these switches can |
| do suffer from the effects of vibration and continual | | | | signal directly to a vehicle's onboard computers or |
| slosh of liquid in the reservoir and mechanical failures | | | | CANbus systems, and these outputs can also be |
| are quite common. Realising that technologies have | | | | specified as "delayed" for specified amounts of time |
| moved on both in sensing devices and engine | | | | (up to 20 seconds) in order to eliminate false signals |
| management systems, engineers began to specify | | | | at start up and during operation when coolant levels |
| solid state coolant level switches should be fitted for | | | | might be experiencing significant turbulence with |
| a number of reasons. Electronic sensors almost | | | | vehicle movement. All of these options are |
| always have no moving parts, they can be | | | | programmable to each customer's requirement, |
| programmed to perform various functions and their | | | | therefore adding value and benefit to the many |
| size is not a limiting factor in their choice of use. All of | | | | different applications and operating environments |
| these features provide a significant advantage over | | | | these switches will encounter. |