Sample Pressure, Temperature, And Flow Rate; Sample Lines & Connections; Sample Conditioning - Ametek 5000 Manual

Sample Pressure, Temperature, and Flow Rate

A pressure reducer/regulator should be installed near the sample tap. Variations in flow
of 10 percent will not affect instrument accuracy. Nominal sample pressure to the system
should be 520 kPa (75 PSI) gauge with a minimum pressure of 200 kPa (30 PSI) gauge.
Temperature of the incoming sample gas should not exceed the analyzer cell tempera-
ture of 60 °C (140 °F). Sample, reference, and moisture generator flow rates through the
cell are set to 250 cc/min (at 2 atm) at the field unit. A bypass flow valve located near the
analyzer will improve analyzer response time.
Sample Lines & Connections
Cleaned and passivated 316L stainless steel* with 0.125 to 0.25 in. OD sample line tubing
is recommended for use throughout the sample system. Note that ordinary stainless steel
tubing can have an internal finish that may cause moisture holdup and slow analyzer
response. Exhaust vent tubing should have an OD of 0.25 inch or greater to prevent back
pressure from affecting the flow rate to the measuring cell.
To avoid sample contamination, the sample stream should not come in contact with
plastic, rubber, oil, grease, or dirt. Use Teflon
all threaded (not compression) connections. Check all sample line connections with a
bubble-type leak detector.
Low temperature and/or high pressure can cause moisture to condense on the sample
line walls. Water (or other liquids) in the sample line can migrate to the analyzer cell
causing the crystal to stop oscillating. This will result in erratic moisture concentration
data until the liquid evaporates and the crystal returns to normal operation state. If this
happens, the calibration of the instrument will no longer be valid. Full calibration and
span adjustment will be necessary.

Water migration to the analyzer cell will destroy the hygroscopic crystal coating. If
analyzer function does not return to normal, the cell must be replaced.
NOTE

Sample Conditioning

Conditioned sample gas is normally used as the reference gas for moisture analysis.
Instrument air or nitrogen may be used if the sample has a high level of particulate or if
sample flow rate is too low. Whether from the sample or a separate source, the reference
gas passes through a standard dryer containing a 3A molecular sieve and an in-line filter
(both included) before entering the field unit. Note that the use of a reference gas dif-
ferent from the sample gas can cause background interference. Refer to Appendix C for
data correction procedure.
* PN 571061017 - stainless steel tubing, 0.125 in. OD x 10 ft.
fluorocarbon resin tape or Loctite
®
Essential Health & Safety Requirements
545 on
®
|
29