User guide

<3 INSTALLATION AND WIRING> 3-1
3.1 Process Measurement Point Considerations
The following criteria should be considered when selecting the installation point in respect to the process
conditions:
• Process Gas Flow Conditions – Laminar, homogenous gas concentration distribution conditions
across the measurement point are recommended.
For circular ducts/stacks this condition is generally at least three unimpaired diameters (D) before and
after a process bend. For rectangular cross sections, the hydraulic ductdiameter (D) is derived from:
D = (4 x duct cross sectional area) / duct circumference
If neither situation exists or is possible, then distribution of the unimpaired section of duct should be
66% on the inlet side and 34% on the outlet side. Profi ling of the proposed measurement point may be
required to ensure that a correct installation point is selected.
• Process Gas Temperature – It is recommended that the analyzer be installed at a location where
temperature fl uctuations are minimized. Generally as a guide, if the temperature of the gas at the point
where the analyzer is to be installed is to vary by more than +/-10˚C (+/-18˚F) then an “Active” input
signal should be used for compensation.
Ensure the analyzer has been selected and confi gured to suit the maximum operating gas temperature.
Lower gas temperatures generally lead to better measurements.
• Process Gas Pressure – It is recommended that the analyzer be installed at a location where pressure
fl uctuations are minimized. Generally as a guide, if the pressure of the gas at the point where the
analyzer is to be installed is to vary by more than +/- 0.05 Bar (+/- 0.725 psi) then an “Active” input
signal should be used for compensation.
Ensure the analyzer has been selected and confi gured to suit the maximum operating gas pressure.
Ensure the process isolation windows have been selected and confi gured to suite the maximum design
gas pressure.
Lower gas pressures generally lead to better measurements.
• Process Dust/Particulate Matter – It is recommended that the analyzer be installed at
a location where dust loadings are minimized. Dust and other particulate matter will
reduce the optical transmission of the measuring laser beam. Within limits, the loss of
optical transmission does not effect the measurement however a Warning alarm will
be initiated when the transmission falls below allowable limits. The amount of dust
loading is also dependant upon the optical path length – Consult Factory for further
details.
Lower dust loads generally lead to better measurements.
3 INSTALLATION AND WIRING
Detailed Installation, Wiring, Utility Drawings are included on a Project Basis. Please contact
Yokogawa for any project specifi c documentation to ensure correct installation. Drawings provided herein
are considered for standard installation use only
IM 11Y01B02-11E-A 5th Edition :June 5, 2012-00