6. Nozzle: Nozzle should be replaced if:
a. The seat width requires adjustment, and the
Dimension from the seat to the first thread is
less than “D” minimum on Table 2.
b. Thread sections are damaged from pitting
and/or corrosion.
c. Top of the nozzle flange and intersecting surface
are damaged from galling and/or tearing.
d. The nozzle flange thickness can change center
to face Dimensions. The minimum dimension for
orifices “D” through “P” is .672” (16.50 mm) and
“Q” through “W” orifices is .797” (20.20 mm).
Nozzle Seat Width: Using a measuring magnifying
glass, (see Lapped Nozzle Seat Widths), determine
whether the finish lapped seat surface must
be machined before lapping. If the seat can be
lapped flat without exceeding the required seat
width, as indicated in Table 3 or 4, it does not
require machining.
To reduce the seat width, the 5º angle surface
must be machined. The nozzle must be replaced
if the D min is reduced below the minimum as
indicated in Table 2.
7. Spring:
Check for any corrosion or pitting.
8. Standard Metal Seated Disc: This disc (Figure 34)
can be machined until the T dimension is reduced to
the minimum, as listed in Table 5. The “N” minimum
dimension must be maintained as well.
9. Thermodisc* Metal Seated Disc: This disc (Figure
37) cannot be machined. It can be lapped as long as
the “A” minimum dimension has been maintained.
If lapping does not fix damaged area, part must be
discarded.
The Thermodisc must be replaced if:
a. Seat defects and damage cannot be lapped out
without reducing the “A” dimension in Figure 37
that is listed in Table 7.
b. If the dimension cannot be measured, replace
the Thermodisc.
10. O-Ring Seated Disc: The O-Ring Retainer cannot
XV. Inspection and Part Replacement (Contd.)
A
B
C
Figure 37: Thermodisc Design
Figure 37b: J-U Orifices
Figure 37c: V&W Orifices
Figure 37a: D-H Orifices
A
C
B
C
B
A
Table 7: Thermodisc Replacement Criteria
Orifice
A min.
in.
mm
D
.006
0.15
E
.006
0.15
F
.006
0.15
G
.006
0.15
H
.006
0.15
J
.013
0.33
K
.014
0.36
L
.014
0.36
M
.014
0.36
N
.014
0.36
P
.017
0.43
Q
.015
0.38
R
.015
0.38
T
.025
0.64
U
.025
0.64
V
.035
0.89
W
.035
0.89
Consolidated 2900 Series POSRV Maintenance Manual
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