Flowserve Logix 1200e LGAIM0044 User Manual
Page 5
Flowserve Corporation, Valtek Control Products, Tel. USA 801 489 8611
44-5
Logix 1000 Series Positioner
Vented-design Conversion
A standard Logix 1000 series positioner is vented
directly to the atmosphere. When supply air is substi-
tuted with sweet natural gas, the following changes
and considerations must be met. Piping must be used
to route the exhausted natural gas to a safe environ-
ment. This piping system may cause some positioner
back pressure in the main chamber (from modulator)
and spool chambers (from actuator). This increase in
pressure is due to restrictions caused by piping losses
from the pipe and fittings
Two chambers must be vented on the Logix 1000
series positioners: the main housing chamber and the
spool valve chamber (Figures 1 and 2). The main
chamber vent is located on the backside of the posi-
tioner (see Figure 1). There is a small, silver-colored
cover (item 24, SKU 10097867), protecting the vent
which must be removed and can be discarded.
A fitting may now be threaded into the
1
/
8
-inch NPT
hole and tubing/piping attached.
NOTE: On rotary products, the mounting bracket cov-
ers the main housing vent. An adequate size access
hole must be drilled in the bracket at the time of
assembly to allow access to the main housing vent.
The maximum allowable back pressure from the col-
lection device on the main housing vent is 1.0 psi
(0.07 bar). Vent flow rate is 244 standard in
3
/min.
WARNING: The back pressure must never rise
above 2.0 psi (0.14 bar).
If this occurs the weather seal boot (SKU 130884),
found on the early versions of the Logix 1000 posi-
tioner, identified by the diagonal window in the main
cover, must be checked for proper sealing, as over-
pressure will move the seal out of place. (See
Figure 4). Damage will not occur to the seal, only seal
alignment will be affected. A typical sign of boot leak-
age is a dramatic deterioration of positioner perfor-
mance. To correct the seal, remove the driver module
and simply re-align back into its groove. If back pres-
sure of 3.5 psi (0.24 bar) is reached, total valve control
will be lost.
Figure 2: Field Termination
Field Terminations
H
AR T Connection
Terminals
4-20 mA Feedback
Terminals (optional)
Housing EARTH
Terminal
Connect Shield at Source Ground
4-20 mA Current Source
Shielded
Cable
Figure 3: Main Housing Vent
Figure 4: Seal on Modulator
M
aximum Allowable
H
ousing
B
ack Pressure
1 psi (0.07 bar)
1 4
-inch NPT x
4
-inch
Swagelok Tube Fitting
1 4
-inch FNTP x
8
-inch
M
NPT R
educer
1
1
Seal B
oot