XXII. 2900 Series POSRV Options
A. Backflow Preventer
When the pilot operated safety relief valve is not
vented directly to atmosphere, it is possible to build
up backpressure in the discharge line. This is typical
in situations where several valves manifold into a
common discharge header. Should the discharge
line pressure exceed the valve inlet pressure, it could
cause the disc to lift and allow reverse flow through
the main valve. This situation can be eliminated
through the use of the Backflow Preventer.
A.1 Disassembly Instructions
1. Remove Shuttle Plug from Shuttle Base by
unscrewing counterclockwise.
2. Remove Shuttle Ball, Tube Filter, and O-Rings
and discard.
A.2 Cleaning
1. If required, clean parts to remove all rust, burrs,
scale, organic matter, and loose particles. Parts
are to be free of any oil or grease except for
lubrication as specified in this instruction.
2. Cleaning agents used shall be such that effective
cleaning is assured without injuring the surface
finishes or material properties of the part.
3. Acceptable cleaning agents include
demineralized water, nonphosphate detergent,
acetone, and isopropyl alcohol. Parts must be
blown dry or wiped dry after cleaning.
4. If you are using cleaning solvents, take
precautions to protect yourself from potential
danger from breathing fumes, chemical burns, or
explosion. See the solvent’s Material Safety Data
Sheet for safe handling recommendations and
equipment.
5. It is not recommended to “sand blast” internal
parts as it can reduce the dimensions of the
parts.
A.3 Parts Inspection
1.
Shuttle Base: Galling or excessive wear on the
threads. Check for any corrosion or pitting.
2.
Shuttle Plug: Galling or excessive wear on the
threads. Check for any corrosion or pitting.
A.4 Reassembly Instructions
Lubricate O-Rings with silicone grease Baker
Hughes P/N SP505.
1.
Assembly of Field Test Connection / Backflow
Preventer Assembly.
a. Insert one of the Small O-Rings into the
Shuttle Base counter bore.
b. Insert the Tube Filter into the Shuttle Base.
c. Insert Shuttle Ball inside of Tube Filter.
d. Insert the other Small O-Ring into the Shuttle
Plug counter bore. Install Larger O-Ring into
groove located on OD of Shuttle Plug.
e. Thread Shuttle Plug into Shuttle Base,
wrench tighten.
Figure 74: Field Test Connection / Backflow
Preventer Option
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Baker Hughes
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