is the weight of silica gel required (in grams).
It is difficult to get exact weights of silica gel required from the above formulae owing
to the many variables that
have to be considered, some of which are difficult to measure. The formulae can, however,
be a useful guide
to indicate the amount of silica gel required to give adequate protection - it is often
prudent to choose the
nearest standard size silica gel sachet above the value that W comes out at. For large values of W,
effective solution than using a single large sachet, is using a number of smaller sachets
spread around the package.
This will reduce the Relative Humidity at a faster rate.
ESPECIALLY AT RISK
Condensation of water vapour
from air will not occur, even when the relative humidity approaches 100%,
providing the air temperature remains constant. So the risk of condensation (and therefore
arises mainly because of large drops in air temperature, where at the new lower
temperature, the volume
of water vapour is too much for the air to hold. Special attention needs to be paid in
(a) variations between daytime and night-time temperatures reach 20 - 30°C.
(b) seasonal temperature variations are large.
(c) temperature variations occur due to the intermittent functioning of encased
apparatus such as
electrical conductors and resistors, fuses, circuit breakers or relay motors, which
release calories when in use.
The greatest risk of condensation is in high humidity environments, where a drop of just
5°C will on average, cause water vapour to condense. As a general rule it is enough to
relative humidity of the enclosed air below 30% to avoid all risk of condensation.
ALLIED DESICCANT PRODUCTS