Bell & Gossett 176R0649C Technologic 502 Series Pump Controller - Manual (Page 11)

11
Harsh Environments
The mechanical and electrical components within
the option panel can be adversely affected due to
the environment. The effects of contaminants in the
air, either solid, liquid, or gas, are difficult to quantify
and control. Depending upon the severity of the
environment, optional NEMA 12, NEMA 3R or NEMA
4 enclosures may be used.
Airborne Liquids
Liquids in the air can condense in components. Water
vapor carried in the air is easily measured as relative
humidity, but other vapors are often more difficult
to measure or control. Steam, oil, and salt water
vapor (near sea locations) may cause corrosion of
components. In such environments, use NEMA 12
enclosures to limit the exchange of outside air into
the option enclosure. Extremely harsh environments
may require a higher level of protection.
Airborne Solids
Particles in the air may cause mechanical, electrical
or thermal failure in components. A NEMA 1 enclosure
provides a reasonable degree of protection against
falling particles, but it will not prevent the fan from
pulling dirty air into the enclosure. A typical indicator
of excessive levels of airborne particles is dust
around the fan. In dusty environments, use NEMA
12 enclosures.
Corrosive Chemicals
In environments with high temperatures and humidity,
corrosive gases such as sulfur, nitrogen and chlorine
compounds cause corrosion to occur in components.
Indications of corrosion are blackened copper or rust
on steel or oxidized aluminum. In such environments,
it is recommended that the equipment be mounted in
a cabinet with fresh air ventilation and that corrosive
compounds be kept away. A non-ventilated cabinet
fitted with an air conditioner as a heat exchanger may
be used. Conformal coated circuit boards may be
specified to reduce the corrosive effects of a harsh
environment.