Instruction Manual
D200158X012
4194S Controllers
July 2018
10
Supply Pressure
WARNING
Severe personal injury or property damage may occur if the instrument air supply is not clean, dry and oil‐free, or
noncorrosive gas. While use and regular maintenance of a filter that removes particles larger than 40 micrometers in
diameter will suffice in most applications, check with an Emerson Automation Solutions field office and industry
instrument air quality standards for use with corrosive gas or if you are unsure about the proper amount or method of air
filtration or filter maintenance.
Supply pressure medium must be clean, dry, and noncorrosive and meet the requirements of ISA Standard 7.0.01 or
ISO 8573-1. A maximum 40 micrometer particle size in the air system is acceptable. Further filtration down to 5
micrometer particle size is recommended. Lubricant content is not to exceed 1 ppm weight (w/w) or volume (v/v)
basis. Condensation in the supply medium should be minimized.
Use a suitable supply pressure regulator to reduce the supply pressure source to 1.4 bar (20 psig) for an output signal
range of 0 and 1.4 bar (0 and 20 psig) and to 2.4 bar (35 psig) for an output signal range of 0 and 2.4 bar (0 and 35
psig).
Remote Set Point Pressure (Option M)
If the controller has the remote set point option, connect the remote set point pressure to the top of the controller
case at the location shown in figure 2-5. Use a clean dry air supply.
Vent
WARNING
Personal injury or property damage could result from fire or explosion of accumulated gas, or from contact with hazardous
gas, if a flammable or hazardous gas is used as the supply pressure medium. Because the controller case and cover
assembly do not form a gas‐tight seal when the assembly is enclosed, a remote vent line, adequate ventilation, and
necessary safety measures should be used to prevent the accumulation of flammable or hazardous gas. However, a remote
vent pipe alone cannot be relied upon to remove all flammable or hazardous gas. Vent line piping should comply with local
and regional codes and should be as short as possible with adequate inside diameter and few bends to reduce case pressure
buildup.
CAUTION
When installing a remote vent pipe, take care not to overtighten the pipe in the vent connection. Excessive torque will
damage the threads in the connection.
If a remote vent is required, the vent line must be as short possible with a minimum number of bends and elbows. Vent
line piping should have a minimum inside diameter of 19 mm (3/4 inches) for runs up to 6.1 m (20 feet) and a
minimum inside diameter of 25 mm (1 inch) for runs from 6.1 to 30.5 m (20 to 100 feet).
If a remote vent is not required, the vent opening (figure 2-5) must be protected against the entrance of any foreign
material that could plug it. Check the vent periodically to be certain it is not plugged.
