Tridon radiator caps are manufactured in ISO9002 accredited
factories and are designed and manufactured to perform as well
as the original equipment radiator cap. Tridon style radiator caps
are in common use both in Europe and North America and suit a
very wide range of vehicle applications.
All Tridon radiator caps are the ~ style and are
suitable for use on both coolant recovery systems and non coolant
A coolant re over stem has an overflow bottle attached to the
radiator and allows a two-way flow of coolant. By allowing coolant
to return to the radiator there is no opportunity for air to enter the
cooling system and the surface area of the radiator in contact with
coolant is also always maintained at the maximum area possible.
A ~tem has no bottle and can only allow the release
of coolant to the atmosphere and the return of air into the radiator.
Non recovery systems are therefore, not as efficient as recovery
Cooling system performance improves when using a recovery
style cap on a non-coolant recovery system due to more uniform
cooling system pressurisation occurring.
The Tridon radiator cap raises and regulates the pressure within
the cooling system by using both pressure and vacuum operated
valves. This pressure results in a higher coolant boiling point.
The raised coolant boiling point provides an increased safety
margin between the opening temperature of the thermostat and
the boiling point of the coolant. As a result, the complete cooling
system operates more efficiently.
In the normal position both the pressure and vacuum valves of
the Tridon cap remain closed (Figure 1 ). The pressure in the
cooling system rises as the temperature rises. When the pressure
begins to exceed the rated pressure the pressure valve opens
(Figure 2) releasing pressurised coolant from the radiator.
The pressure valve closes as the excess cooling system pressure
reduces. The cycle of opening and closing the pressure valve
continues, maintaining the appropriate system pressure and
protecting cooling system components from exposure to excessive
cooling system pressure.
The cooling system pressure reduces when the system cools down
and the coolant contracts. A negative cooling system pressure
will develop unless there is a way for the pressure in the system
to equalise. This negative pressure can cause radiator tanks and
hoses to collapse causing expensive damage to the cooling
To prevent this damage the Tridon radiator cap has an additional
vacuum valve that allows coolant or air to return to the radiator
as the pressure reduces (Figure 3). This serves a dual purpose
nf allowino the coolin_ci sVstem pressure to equalise as well as