Rosemount 755, Инструкция по эксплуатации

Страница: 79 / 94

S
ERVICE AND
M
AINTENANCE
748183-H
7-5
Rosemount Analytical
December 1997
7.3.4 S
USPENSION
If the suspension has been damaged, the cause may be improper operating
conditions.
Maximum permissible operating pressure for the detector is 10 psig (69 kPa gauge
pressure). To ensure against over-pressurization, a pressure relief valve may be
inserted into the sample inlet line. In addition, a check valve should be inserted into
the vent line, if connected to a manifold associated with a flare or other outlet that is
not at atmospheric pressure. If the detector is over-pressurized, the suspension could
break.
To verify correct operation:
1. Turn electrical power to analyzer OFF.
2. Remove optical bench assembly (see Section 7.4.2, steps 1 through 4.)
3. With 100% nitrogen flowing through the analyzer, note the position of the
suspension.
4. Admit air and note response of suspension. It should rotate clockwise (as viewed
from the top) and to the right (as viewed through the window).
Failure to rotate indicates that the suspension has been damaged and that the
detector assembly must be replaced. See Section 7.4.1.
7.4 DETECTOR COMPONENT REPLACEMENT
7.4.1 D
ETECTOR
R
EPLACEMENT AND
C
ALIBRATION
R
EPLACEMENT
Prior to removal of the detector, remove power from instrument and stop flow of
sample gas.
1. Remove the four screws securing the detector cover plate.
2. Disconnect cable from J12 on the detector assembly.
Note
Note how the rubber sample lines are looped into a "long coil". When
reinstalling the sample lines they must be configured in the same way.
This precaution isolates the detector from the effects of mechanical
vibration. Otherwise vibration waves could travel upward along the tubing
walls, resulting in noisy readout.
3. Refer to Figure 7-3. Using needle-nose pliers, squeeze the hose clamps to
disconnect the rubber sample lines from the metal inlet and outlet tubes of the
detector assembly.