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4
Atmospheric Regulator or Zero Governor
Size
Outlet Pressure Range
Springs
3/4", 1" and 1-1/4" 121-8
1-1/2" w.c. vacuum (–1-1/2" w.c.) to + 1-1/2" w.c.
Main Spring (Red-Black)
143-82-021-00
Counterspring (Black-Red)
121-10-021-50
1-1/2", 2" and 2-1/2" 121-12
1" w.c. vacuum (-1" w.c.) to + 1-1/2" w.c.
Main Spring (Red-Black)
143-82-021-00
Counterspring
120-10-021-10
3" and 4" 121-16
1-1/4" w.c. vacuum (-1-1/4" w.c.) to + 1-1/4" w.c.
Main Spring only
121-62-021-54
Outlet Pressure Ranges and Springs
Maximum
Nominal
Outlet
Spring
Spring
Inlet
Diaphragm
Size
Pressure Range
Color
Part Number
Pressure
Size
1-1/2" to 3-1/2" w.c.
Blue-Black
143-82-021-01 (main spring)
Black-Red
121-10-021-50 (counterspring)
1-1/2" to 12" w.c.
Green-Black
143-82-021-02 (main spring)
Black-Red
121-10-021-50 (counterspring)
3/4", 1" and 1-1/4" **
3-1/2" to 6-1/2" w.c.
Red-Black
143-82-021-00
60 psi
8"
Model 121-8
5" to 8-1/2" w.c.
Blue-Black
143-82-021-01
6" to 14" w.c.
Green-Black
143-82-021-02
12" to 28" w.c.
Green (2" O.D.)
143-16-021-05
1 psi to 2 psi
Orange (2" O.D.)
143-16-021-06
2 psi to 4-1/4 psi
Black
143-16-021-07
3/4", 1" and 1-1/4" **
3 psi to 6-1/2 psi
Cadmium*
143-16-021-08
Model 121-8HP
6 psi to 10 psi
Cadmium*
143-16-021-08 (outer)
60 psi
8"
White
143-16-021-13 (inner)
1-1/2" to 3-1/2" w.c.
Red
143-16-021-03 (main spring)
_
120-10-021-10 (counterspring)
1-1/2" to 12" w.c.
Maroon
121-42-021-00 (main spring)
_
120-10-021-10 (counterspring)
1-1/2", 2" and 2-1/2"
3-1/2" to 6-1/2" w.c.
Red (2" O.D.)
143-16-021-03
60 psi
12"
Model 121-12
5" to 8-1/2" w.c.
Blue (2" O.D.)
143-16-021-04
6" to 14" w.c.
Green (2" O.D.)
143-16-021-05
12" to 28" w.c.
Orange (2" O.D.)
143-16-021-06
1 psi to 2 psi
Black
143-16-021-07
1-1/2 psi to 3 psi
Cadmium
143-16-021-08
1-1/2", 2" and 2-1/2"
1 psi to 2 psi
Orange (2" O.D.)
143-16-021-06
60 psi
8"
Model 121-8
2 psi to 4-1/4 psi
Black
143-16-021-07
1-1/2", 2" and 2-1/2"
3 psi to 6-1/2 psi
Cadmium*
143-16-021-08
Model 121-8HP
6 psi to 10 psi
Cadmium*
143-16-021-08 (outer)
60 psi
8"
White
143-16-021-13 (inner)
3-1/2" to 6-1/2" w.c.
Red (3" O.D.)
121-62-021-50
3" and 4"
5" to 8-1/2" w.c.
Blue (3" O.D.)
121-62-021-51
15 psi (4" 121)
Model 121-16
6" to 14" w.c.
Green (3" O.D.)
121-62-021-52
40 psi (3" 121
16"
14" to 28" w.c.
Orange (3" O.D.)
121-62-021-53
1/2 psi to 1-1/4 psi
Yellow
121-62-021-56
3" and 4"
1 psi to 2 psi
Black
143-16-021-07
15 psi (4" 121)
12"
Model 121-12
1-1/2 psi to 3 psi
Cadmium
143-16-021-08
40 psi (3" 121
*Requires High Pressure Spring Adjustment.
** 3/4" x 3/4" not available.
Installation and Maintenance
Model 121 Regulators