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Instruction Manual
245364-V
May 2002
Rosemount Analytical Inc. A Division of Emerson Process Management Installation 2-11
Model 755A
2-8 PURGE KIT (OPTIONAL)
The Purge Kit (PN 643108) is designed to
equip the Model 755A with Type Z Air Purge
per National Fire Protection Association
Standard NFPA496-1986, Chapter 2
1
.
WARNING
POSSIBLE EXPLOSION HAZARD
This analyzer is of the type capable of
analysis of sample gases which may be
flammable. If used for analysis of such
gases, the instrument must be either in an
explosion-proof enclosure suitable for the
gas, or, protected by a continuous dilution
purge system in accordance with Standard
ANSI/NFPA-496 (Chapter 8) or IEC
Publication 79-2-1983 (Section Three)
If explosive gases are introduced into this
analyzer, the sample containment system
must be carefully leak-checked upon
installation and before initial start-up,
during routine maintenance and any time
the integrity of the sample containment
system is broken, to ensure the system is
in leak-proof condition.
Internal leaks resulting from failure to
observe these precautions could result in
an explosion causing death, personal
injury and/or property damage.
The kit consists of the following:
PART NO. DESCRIPTION
190697 Purge Inlet Fitting
645835 Purge outlet Fitting
082787 Warning Label
856156 Sealant (Duxseal)
1
These standards are not applicable to enclosures into
which a flammable gas or vapor mixture is introduced,
such as by a continuous sample containment system that
is subject to accidental leakage.
NOTE:
To conform to NFPA Type Z requirements,
the warning label must be applied to the
analyzer front cover. If the analyzer is
ordered factory equipped with the Purge
Kit, this label is applied at the factory.
Installation options are shown in Figure 2-8
(page 2-12). Use only clean dry air or suitable
inert gas for the purge supply.
Recommended supply pressure is 20 psig
(138 kPa), which provides a flow of
approximately 8 cubic feet per hour (4 liters
per minute) and a case pressure of
approximately 0.2 inch of water (50 Pa).
With a flow rate of 4 liters per minute, four
case volumes of purge gas pass through the
case in 10 minutes.
All conduit connections through the case must
be sealed thoroughly with the sealant supplied
in the kit. The sealant (applied from the
interior of the case) must thoroughly cover all
existing leads, as well as the conduit fitting.