SMAR FY301, Instruction, Operations & Maintenance Manual

Page: 19 / 82

Installation
1.11
Air Supply Requirements
Before the air supply is connected to the positioner, we recommend the hose is opened freely for 2
to 3 minutes to allow any contamination to be blown out. Direct the air jet into a large paper towel to
trap any water, oil, or other foreign materials. If this indicates that the air system is contaminated, it
should be properly cleaned.
As soon as the positioner is connected and powered, internal air leakage will provide protection
against corrosion and prevent moisture inside. For this reason, it is strongly recommended to keep
the positioner pressurized as much as possible.
Recommendations for Instrument Air Supply System
Instrument air quality shall be superior to that of industrial compressed air. Humidity, suspended
particles and oil may impair the instrument operation, either temporarily or permanently in case of
internal parts wearing.
As per standard
ANSI/ISA S7.0.01 - 1996 - Quality Standard for Instrument Air
, instrument air shall
have the following characteristics:
Dew point
10 ° C below minimum instrument temperature
Size of particles (airborne)
40 µm (maximum)
Oil content
1 ppm w/w (maximum)
Contaminants
free from corrosive flammable gases
This standard recommends that the compressor intake be located in an area free from process spills
and fitted with and adequate filter. It also recommends the use of non-lubricated type compressors,
in order to prevent air contamination by lubricating oil. Where lubricated type compressors are
adopted, there shall be used means to make the air oil free.
Figure 1.13 and 1.14 shows a typical system for air supply and air quality conditioning.
COMPRESSOR
INTAKE
COMPRESSOR
AFTERCOOLER
CONDENSATE
SEPARATOR
WITH DRAIN
AIR RECEIVER
WITH DRAIN
Figure 1.13 - Air Supply System
OIL AND WATER
MIST PREFILTER
WITH DRAIN
AIR
DRYER
DRY AIR
AFTERFILTER
Figure 1.14 - Air Quality Conditioning System