The Equipment Design Process
339
11.3.1.3 Electrical Components
Electrical distribution systems in most plants consist of galvanized iron or
aluminum conduit and enclosures. These materials are often subject to corrosive attack from atmospheric pollutants. Alternative materials may be used
to overcome this attack. It is possible to use such items as:
Polyvinyl chloride (PVC)-coated conduit and enclosures
•
FRP enclosures
•
Stainless steel enclosures
•
Seals used in hazardous operating areas to prevent hazardous gases from
entering the electrical enclosure (motor starter, disconnect switch, motor,
etc.) can be used in nonhazardous areas to prevent corrosive fumes from
entering the enclosures. This will reduce corrosion of the working parts.
Regardless of which material is used, enclosures and conduits should be
located so that
Free drainage can occur.
•
Places where dirt and water can accumulate are eliminated.
•
This will help prevent corrosion by reducing the time of wetness.
11.3.1.4 Control Rooms
Most power plants and facilities contain control rooms, electric motor control
centers, instrument control rooms, and computer centers. These are usually
maintained under a slight positive pressure with make-up air being introduced with air from the outside. In many instances it is possible for this air to
be contaminated with atmospheric pollutants such as sulfur oxides, hydrogen chloride, chlorides, hydrogen sulfide, dust, and other contaminants.
These gases and dusts can cause serious damage to sensitive circuitry found
in computers, microprocessors, microswitches, and other delicate electronic
equipment. If corrosive gases are removed from these make-up streams,
costly maintenance and downtime will be prevented.
The removal of these gases and particulate matter from the make-up air
stream is strongly advised. It can be accomplished by treating incoming air
streams in the following manner:
1. Install a filter, with a rating of approximately 25 to 30% ASHRE on
the fan inlet.
2. On the discharge side of the fan, pass the air through an activated
carbon bed, ensuring that the carbon bed is designed to remove the
particular gases and or vapors present.
339
11.3.1.3 Electrical Components
Electrical distribution systems in most plants consist of galvanized iron or
aluminum conduit and enclosures. These materials are often subject to corrosive attack from atmospheric pollutants. Alternative materials may be used
to overcome this attack. It is possible to use such items as:
Polyvinyl chloride (PVC)-coated conduit and enclosures
•
FRP enclosures
•
Stainless steel enclosures
•
Seals used in hazardous operating areas to prevent hazardous gases from
entering the electrical enclosure (motor starter, disconnect switch, motor,
etc.) can be used in nonhazardous areas to prevent corrosive fumes from
entering the enclosures. This will reduce corrosion of the working parts.
Regardless of which material is used, enclosures and conduits should be
located so that
Free drainage can occur.
•
Places where dirt and water can accumulate are eliminated.
•
This will help prevent corrosion by reducing the time of wetness.
11.3.1.4 Control Rooms
Most power plants and facilities contain control rooms, electric motor control
centers, instrument control rooms, and computer centers. These are usually
maintained under a slight positive pressure with make-up air being introduced with air from the outside. In many instances it is possible for this air to
be contaminated with atmospheric pollutants such as sulfur oxides, hydrogen chloride, chlorides, hydrogen sulfide, dust, and other contaminants.
These gases and dusts can cause serious damage to sensitive circuitry found
in computers, microprocessors, microswitches, and other delicate electronic
equipment. If corrosive gases are removed from these make-up streams,
costly maintenance and downtime will be prevented.
The removal of these gases and particulate matter from the make-up air
stream is strongly advised. It can be accomplished by treating incoming air
streams in the following manner:
1. Install a filter, with a rating of approximately 25 to 30% ASHRE on
the fan inlet.
2. On the discharge side of the fan, pass the air through an activated
carbon bed, ensuring that the carbon bed is designed to remove the
particular gases and or vapors present.