Moisture content of sand used to manufacture
glass is critical. Sand of too low a moisture content produces
an excessive amount of dust in the furnace. Too much moisture
requires greater usage of energy, increasing cost of production,
and affects the quality of the end product.
Sand, glass cullet and other materials, depending on the type
of glass are fed into a mixer. Owing to the potentially large
variation in moisture content of these constituents the quantity
of water that needs to be added to a batch varies. By measuring
the moisture content of the main constituent, sand, the guess
work can be removed. A feed forward control loop can be used
with the automatic water addition system.
On the sand feed conveyor to the mixer
Typically the gauge is installed above a conveyor, approximately
8” from the product, this allows for variations in the
sand bed depth. If the gauge is used in a control loop, or
the gauge output is continuously recorded, it is important
to use a gating device, such as a photo-electric eye. The
photo-eye sends a signal to the gauge when it no longer sees
product, this causes the gauge to hold its analog output until
the photo-eye sees product once again.