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15. Moisture Protection
15.1 Silica Gel Pack
Due to the size of the
90-FL
enclosure, it tends to expand in hot environments and contract in cold
environments. This process can cause moist air to be drawn into the enclosure, which would then
cause corrosion damage to the circuit.
To avoid this problem, TPS has mounted a breathing system inside the enclosure. This system
consists of a long, thin tube which is vented to the atmosphere at one end and into a bottle of Silica
gel at the other end. This ensures that the
90-FL
breathes dry air. In humid environments, the Silica
gel pack should be regularly checked.
To check the Silica gel pack…
1.
Undo the 4 plastic screws on the rear of the unit.
2.
Inspect the bottle of Silica gel.
Blue indicates that the Silica gel is still dry (proceed to step 5).
Pink indicates that the Silica gel is moist (proceed to step 3).
3.
Empty the Silica gel into a microwave proof dish and place it into a microwave oven.
Place approximately 100mL water in a microwave proof cup into the microwave oven. This
will absorb some of the microwave energy and stop the Silica gel balls bursting.
Turn the microwave oven ON using a moderate setting for approximately 1 minute, or until the
Silica gel turns blue.
CAUTION : THE SILICA GEL MAY BE VERY HOT AT THIS POINT.
4.
Remove the Silica gel from the microwave oven and allow to cool.
Pour the Silica gel back into the bottle and re-fit the bottle onto the rear cover of the instrument.
5.
Re-fit the rear cover onto the instrument, ensuring that is the correct way around. The cover has
locating lugs in two of the corners to make correct fitment simple.
15.2 Corrosion Inhibitor Tab
To provide extra protection against corrosion, the
90-FL
is fitted with a Senson
®
Vapaguard™
corrosion inhibitor tab. This tab disperses a special vapour throughout the enclosure which actively
fights corrosion on any of the components.
The corrosion inhibitor tab has a limited life and should be replaced every 2 to 3 years to ensure
effective protection.
The TPS part number for a new corrosion inhibitor tab is NRP2.