2.2.3
Flame Traps
Flame traps shall be provided in the gas piping system between each source
of ignition and the digesters. Flame traps shall be located as close as
possible to the source of ignition, the distance not to exceed 7.5 m 25 feet.
Each flame trap shall have a capacity to pass at least [_____] cubic
meters cubic feet of gas per hour at a pressure loss not to exceed [_____]
127 Pa 1/2 inch of water column. The flame trap element shall prevent the
passage of flame and shall permit convenient replacement of the entire
element. The unit shall also include a spring actuated thermal shut-off
valve, held open by a fusible element, to automatically close in the
presence of burning mixtures.
2.2.4
Sediment Traps
Sediment traps shall be provided in the gas piping system prior to all
other equipment. Traps shall be baffled and provided with a sealed, safe
means of determining the liquid level without closing the gas supply line.
Sediment traps shall be of cast iron, ductile iron, or galvanized steel
construction with a minimum capacity of 38 liters 10 gallons of accumulated
sediment and condensate. Supply line connections shall be equal to the
supply line size. A manual drip trap shall be provided to drain
accumulated condensate from the sediment trap.
2.2.5
Drip Traps
Drip traps shall be provided in the gas piping network at the low points
and on the upstream side of each gas meter. Drip traps shall be manually
operated, shall be constructed of cast iron, ductile iron, or galvanized
steel, and shall have a minimum capacity of 2 liters two quarts. Trap
construction shall effectively prevent leakage of gas from the system when
the trap is being drained.
2.2.6
Gas Meters
Gas meters shall be provided to measure the gas production of each digester
and the volume of gas delivered to the waste gas burner and the sludge
heating system. Gas meters shall be rated at [_____] cubic meters per
second cubic feet per minute at [_____] Pa inches water column pressure
drop with a capacity of 200 percent rated flow. Meters shall be
constructed of materials resistant to the corrosive effects of digester
gas. A valved bypass shall be provided around each gas meter.
2.2.7
Pressure Indicating Gauges
Pressure indicating gauges shall be provided in the gas piping system to
enable monitoring of digester pressure and to enable the pressure balancing
at the waste gas burner and the digester heating system. Gauges shall be
direct reading in Pa inches of water and shall be [assembled as one unit,
wall mounted,] [individually mounted on the pipe,] with shut-off cocks.
Shut-off cocks shall be pinned and sealed to prevent gas leakage.
2.2.8
A pressure relief valve shall be provided in the gas line to the waste gas
burner and connected to the upstream side of the flame trap. Pressure
relief valves shall maintain a predetermined back pressure throughout the
system at settings from 1.25 to 2.49 kPa 5 to 10 inches of water column and
shall release surplus gas to the waste gas burner. The relief valve shall
SECTION 11380
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