
Y690A Series
3
Principle of Operation
Refer to Figure 2. When downstream demand
decreases, the pressure under the diaphragm
increases. This pressure overcomes the regulator
setting (which is set by a spring). Through the action
of the sliding pusher post assembly, lever, and valve
stem the valve disk moves closer to the orice and
reduces gas ow. If demand downstream increases,
pressure under the diaphragm decreases. Spring
force pushes the pusher post assembly downward, the
valve disk moves away from the orice, and the gas
ow increases.
INLET PRESSURE
OUTLET PRESSURE
ATMOSPHERIC PRESSURE
B2625
SLIDING PUSHER POST
OVERPRESSURE SPRING
VALVE STEM
LEVER
VALVE DISK
PITOT TUBE FOR
TYPES Y690A
AND Y690AH
Figure 2. Y690A Series Operational Schematic
Table 3. Maximum Operating Inlet Pressures
ORIFICE
SIZE,
INCHES (mm)
OUTLET PRESSURE RANGE, PSIG (bar)
Types Y690A and Y690AM Types Y690AH and Y690AHM
1 to
2.5-Inches w.c.
(2 to 6 mbar)
2.5 to
7-Inches w.c.
(6 to 17 mbar)
5 to
10-Inches w.c.
(12 to 25 mbar)
7 to
16-Inches w.c.
(17 to 40 mbar)
15-inches w.c.
to 1.2 Psig
(37 mbar to
0,08 bar)
1.2 to 2.5 Psig
(0,08 to
0,17 bar)
2.5 to 4.5 Psig
(0,17 to
0,31 bar)
4.5 to 7 Psig
(0,31 to
0,48 bar)
1/8 (3,2) 150 (10,3) 150 (10,3) 150 (10,3) 150 (10,3) 150 (10,3) 150 (10,3) 150 (10,3) 150 (10,3)
1/4
3/8
(6,4)
(9,5)
40
20
(2,8)
(1,4)
60
20
(4,1)
(1,4)
75
35
(5,2)
(2,4)
75
35
(5,2)
(2,4)
75
35
(5,2)
(2,4)
150
60
(10,3)
(4,1)
150
60
(10,3)
(4,1)
150
60
(10,3)
(4,1)
1/2
9/16
(13)
(14)
10
5
(0,69)
(0,34)
10
5
(0,69)
(0,34)
8
5
(0,55)
(0,34)
8
5
(0,55)
(0,34)
8
5
(0,55)
(0,34)
10
6
(0,69)
(0,41)
12
8
(0,83)
(0,55)
12
8
(0,83)
(0,55)
Table 4. Flow and Sizing Coefcients
ORIFICE SIZE,
INCHES (mm)
WIDE-OPEN COEFFICIENTS
(FOR RELIEF VALVE SIZING)
C
1
K
m
IEC SIZING COEFFICIENTS
C
v
C
g
X
T
F
D
F
L
1/8
1/4
3/8
1/2
9/16
(3,2)
(6,4)
(9,5)
(13)
(14)
0.35
1.43
3.14
5.71
7.14
12.3
50
110
200
250
35 0.79 0.78 0.50 0.89
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