Dresser 5C15 Установка, эксплуатация и обслуживание - Страница 5
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Печатать страницу2. Meter Orientation:
Connect meter inlet to the gas supply side of the line,
insuring the gas flow will be in the same direction as
the arrow on the meter body nameplate (i.e., arrow
pointing downward for Top Inlet)
3. Install the meter without piping strain to prevent a
binding of the casing and impellers.
4. Check the orientation of the meter with a level. The
meter must be level within 1/16" per foot (5mm/m)
in any direction, side to side, front to back.
Meter Start-Up
Slowly pressurize the meter in
accordance with the following
recommendations:
IMPORTANT: Do not exceed
5 psig/second (35 kPa/second)
maximum when pressurizing.
Rapid pressurization can cause
an overspeed condition which
may damage the meter.
Resulting damage is not
covered by warranty.
a. Open the bypass and
outlet (downstream of
meter) gas valves.
b. Partially open the meter inlet gas valve until the
meter starts operating at low speed. Throttling of
the bypass valve may be necessary to initiate gas
flow through the meter. Verify gas is flowing through
the meter by watching for movement of the "Half
Foot" dial. If movement is present, go to step c. If
the dial is not turning, verify gas is being delivered
to the meter. If gas is flowing to the meter inlet and
the dial is not moving, go to step e.
c. Let the meter operate at low speed for several
minutes. Listen closely for unusual scraping or
knocking sounds.
d. If operation is satisfactory, go directly to step f.
e. If unusual sounds are present or the accessory
unit's "Half Foot" dial is not turning, place the meter
in bypass. Slowly depressurize and vent all pressure
the meter set before checking for piping
misalignment, piping strain, torsion, or other related
problems. Once the problem has been resolved,
repeat the start-up procedure beginning with step a.
DANGER: Slowly depressurize and vent all pressure from
the meter set before working on meter.
f. Gradually open the inlet valve until full line flow is
passing through the meter and the inlet valve is
fully open.
g. Slowly close the bypass valve.
h. Follow your company authorized procedure or
common practice to leak test the meter and all
connections. Soapy water, Snoop
are commonly used for this procedure.
Snoop is a registered trademark of the Swagelok Company.
INSPECTION AND MAINTENANCE
Lubrication
NO LUBRICATION IS REQUIRED. This meter incorpo-
rates permanently lubricated bearings and gears.
Meter Level
Since the meter is supported entirely by the gas
pipe line, movement of the piping through accident,
settling of the ground or other causes can impede
meter operation and accuracy. Refer to "INSTALLATION"
procedures. Make sure the meter remains level within
1/16" per foot (5mm/m) in any direction, side to side,
front to back.
Meter Testing
The Differential Rate Test is an accurate and convenient
method of comparing a rotary meter's performance at
any time with its original performance. This and other
commonly used test methods are covered later in this
manual under "TESTING".
Cleaning - If there is any evidence of dirt or dust in the
meter, a suggested method for removal is to windmill the
impellers (at a speed less than maximum capacity) by
injecting controlled compressed air from a nozzle into
the meter inlet.
TESTING
General
Rotary meters can be tested for accuracy by several
industry accepted methods. These test methods include,
but are not limited to: bell or piston prover, transfer
prover, sonic nozzle prover, and critical flow proving. The
Differential Pressure Test is unique to rotary meters and is
an accurate and convenient method of comparing a
meter's performance to previous or original performance
records. It is accepted by many State Utility Commissions
as a means of periodically substantiating that the original
accuracy of a meter has remained unchanged.
Differential Pressure Test
A change in the meter's internal resistance can affect
rotary meter accuracy. Any significant increase on the
meter's internal resistance to flow will increase the pres-
sure drop between the inlet and outlet of the meter, thus
increasing the differential pressure, Therefore, the meter
differential pressure appears as a prime indicator of
meter condition.
A test under actual operating conditions will provide the
most reliable data for future checks of a meter's operating
condition. Although accuracy cannot be directly deter-
mined by a differential test, results have shown that an
increase of up to 50 percent in differential pressure can
be tolerated without affecting meter accuracy at the higher
flow rates (25% and above) by more than 1 percent.
Supportive technical data is available, upon request.
®
and gas analyzers
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