Ametek 5000 Instrument Manual page 42

1. Assure that there is sufficient pressure to maintain 30 psig on analyzer input.
2. Adjust the back pressure regulator (4) and flow controls (1,2,3) if necessary, until pressure
gauge (6) reads the equivalent of 103 kPa gauge (15 psig) regardless of which gas is flowing.
Back pressure values are referenced to standard atmospheric pressure. Correct pressure
gauge setting depends on the average barometric pressure at the specific system location.
To determine the proper gauge setting, use the following calculations.
• Gauge setting in kPa: = 103 + [100 – (average barometric pressure in kPa)]
Example:
• Gauge setting in psig= 15 + [14.7 – (average barometric pressure in psia)]
Example:
3. Close the sample and reference flow controls valves. Do not over tighten the valves. Leave
the moisture generator flow valve open. This flow is the most critical and will be set using
a Bubble-O-Meter® (PN 303030003) or similar flow measuring device.
4. Disconnect the moisture generator valve switching wire from field unit TB1-8. This step will
default the system to the verification operation.
5. Connect the Bubble-O-Meter® or other flow measuring device to the
regulator fitting. Refer to Appendix A for proper usage of a Bubble-O-Meter®.
6. If using a Bubble-O-Meter®, the transit time required for 500 mL of gas at ambient pressure
and gas temperature must be normalized to the transit time for 500 mL at pressure ~760 mm
Hg and gas temperature ~27°C. Use the following equation and the data found in Table II to
determine the transit time at the ambient pressure and temperature. Note that this calculation
may not be necessary if another flow measuring device is used.
Transit Time (sec) = (60)
where:
7. Adjust the moisture generator flow control (3) until the soap bubble requires the calculated
transit time to travel 500 mL. (Since the flowmeter is calibrated for air @ STP the reading on
the flowmeter will not indicate 500 ml/min). Refer to Fig 4-6.
8. Since moisture generator flow and back pressure interact with each other, recheck them now
.
9. Using a marking pen, mark the flowmeter at the ball position to indicate the desired flow.
Disconnect the flow measuring device.
Press and hold the reset field unit switch (S1) and adjust the sample flow control valve to the
flowmeter mark.
10. If necessary, readjust the back pressure regulator (4).
3-8 5000 Multi Point Moisture Analyzer
Average barometric pressure at installation site is 90 kPa. The proper
gauge setting is:
103 + [100 – (90)] = 103 + 10 = 113 kPa
Average barometric pressure at installation site is 13 psia. The proper
gauge setting is:
15 + [14.7 – (13)] = 15 + 1.7 = 16.7 psig
( ( )
P1 – P2
760 273 + T
P = ambient pressure (mm Hg)
1
P = water vapor pressure from Table II
2
T = gas temperature inside Bubble-O-Meter
gas
)
298
gas
®
/ inch back pressure
1
4