Emerson Rosemount 485 Annubar Quick Installation Manual page 15

Quick Installation Guide
00825-0500-4809, Rev CA
September 2003
S 8
TEP CONTINUED
The following restrictions and recommendations apply to impulse
piping location:
1. Impulse piping that runs horizontally must slope at least one inch
per foot (83 mm/m).
• Slope downward (toward the electronics) for liquid and steam
applications
• Slope upward (toward the electronics) for gas applications.
2. For applications with temperature below 250 °F (121 °C), impulse
piping should be as short as possible to minimize temperature
changes. Insulation may be required.
3. For applications above 250 °F (121 °C), impulse piping should
have a minimum length of one foot (0.3048 m) for every 100 °F
(38°C) temperature increase over 250 °F (121 °C). Impulse piping
must be non-insulated to reduce fluid temperature. Any threaded
connections should be checked after the system reaches the
intended temperature because connections may come loose with
contraction and expansion caused by temperature change.
4. Outdoor installations for liquid, saturated gas, or steam may require
insulation and heat tracing to prevent freezing.
5. When impulse piping is longer than six feet (1.8 m) the high and
low impulse lines must be positioned together to maintain equal
temperature. They must be supported to prevent sagging and
vibration.
6. Impulse lines should be positioned in protected areas or against
walls or ceilings. Use appropriate pipe sealing compound rated for
the service temperature on all threaded connections. Do not place
the impulse piping near high temperature piping or equipment.
An instrument manifold is recommended for all installations. Manifolds
allow an operator to equalize the pressures prior to zeroing and
isolates the process fluid from the electronics.
Threaded Flo-Tap 485 Annubar
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