Flowserve 3400IQ Digital Positioner - Manual (Page 65)

6
Logix 3400IQ Digital Positioner FCD LGENIM3401-00 – 06/06
flowserve.com
Figure 20: Main Housing Vent
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 c

Figure 21: Spool Cover Vent
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The spool valve chamber (see Figure 21) must also be vented through the spool valve cover.
Vented-design Logix 3400IQ positioners are supplied from the factory with a fitting installed in the
spool valve cover (item SKU 179477). Connect the necessary tubing/piping to this fitting to route
the exhausted natural gas to a safe environment. The maximum allowable back pressure in the spool
valve chamber is 8 psig (0.55 barg). Pressures greater than 8 psig will cause vented gas to leak past
the spool cover O-ring to the atmosphere and will result in overshoot of the positioner.