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8
EN-DFA Series
North America
Only
installing the temperature sensor in the appropriate
instrumentation port on the downstream or unprotected
(“hot”) side of the flame arrestor. Model EN-DFA
detonation flame arrestors are bi-directional, so if a
temperature sensor is not requested with the flame
arrestor, then no flow arrow will be installed on the unit,
and the end user shall be responsible for installation of
the temperature sensor on the unprotected (“hot”) side
of flame arrestor. This is the side of the flame arrestor
closest to the source of ignition.
A temperature rise of 20
K (36°F / 20°C) above the
flame arrestor maximum operating temperature or 20
K
(36°F / 20°C) above the process operating temperature,
whichever is lower but not to exceed 20
K (36°F / 20°C)
above the flame arrestor operating temperature, is the
recommended activation temperature for initiation of
measures against stabilized burning.
Note that a rise in temperature measured by
the temperature sensor can indicate to the user
deflagration and/or detonation events have occurred
as well. This should be used as a trigger to investigate
what conditions have lead to ignition of flammable
vapors, to inspect the flame arrestor for damage, and
to initiate appropriate corrective actions relative to
process system and safety.
Temperature sensors installed by Emerson or installed
by the user shall follow the specifications or Table 6.
Different temperature sensors may be installed by
the end user, however these must comply with the
safety specifications in Table 6. The use of alternate
temperature sensors must include evidence of
equivalent response rates to the specified sensors in
Table 6, particularly as the EN-DFA Series is rated for
short time burning.
If t
BT
is exceeded during a short-time burning situation,
the flame arrestor safety cannot be assured.
If an elevated temperature has been detected by
the temperature sensor, whether due to flash back
or stabilized burn, the temperature sensor shall be
inspected for damage and replaced as necessary.
If the recorded temperature exceeds the design
temperature of the temperature sensor then the
measuring probe shall be replaced.
Pipe Length
Extended lengths of pipe allow the flame to advance
into more severe states of flame propagation such as
high pressure deflagrations and detonations. Although
the detonation flame arrestor is not limited by pipe
length, using a minimum length is a preferred design
and installation practice.
Bends and/or Flow Obstructions
△
CAUTION
For maximum safety, avoid bends
and flow obstructions within 10 pipe
diameters but not less than 10 ft / 3 m
on the protected side of the detonation
flame arrestor.
Figure 6.
Flange Pattern Tightening Sequence
