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4
2
1
3
5
9
To Service Seal Diaphragm – 12b
1.
Remove valve
15
per section “To Service Valve –
15
”, item 1.
2.
Remove bolts
29
and upper case assembly and then remove
seal diaphragm assembly
12
.
3.
To disassemble
12
, unscrew piston
12a
from stem
12d
.
Use a spanner wrench in notch in skirt of piston (this can also
be done by inserting a standard 7/32" Allen wrench in the notch).
– To reassemble, replace parts in reverse sequence.
Make certain that fabric side of seal diaphragm
12b
faces
upward and “rubber” side faces downward toward body.
Do not pinch loop in seal diaphragm
12b
between ring
33
and
centerpiece
27
. Also, rounded edge of
33
faces upward toward
seal diaphragm
12b
.
Make sure the screwed connection
between 11h and 12d is loose by approximately 1/2 turn.
To
do this, carefully rotate seal diaphragm assembly
12
clockwise
until this screwed connection bottoms (do not jam it together).
Then back-off seal diaphragm assembly
12
counterclockwise
approximately 1/2 turn. The
11h
to
12d
screwed
connection must not be tight
Variations
Vacuum Breaker
Vacuum Breakers
are vacuum limiting devices. In their general function, they can be compared
to relief valves or back pressure regulators.
The breaker outlet and control line are piped to the vacuum. The breaker inlet connects to a lesser
vacuum, to atmosphere or to a positive pressure. The maximums for the positive pressure are
60 psi for 3/4" through 2-1/2" sizes, 40 psi for 3" and 15 psi for 4". The vacuum breaker is normally
closed and excess vacuum creates a valve opening movement which increases flow from the inlet
and thereby relieves or “breaks” the excess.
All of the pipe sizes listed on Page 24 are available 3/4" through 4". Note on the cutaway drawing
that the main spring is reversed to provide the upward closing force on the valve. Except for certain
parts used in the spring assembly, everything else is interchangeable with standard 121 regulators.
Vacuums and Springs
Vacuum Range
w.c. vacuum
Spring
Size
(– w.c.)
Spring Color
Part Number
3" to 6-1/2"
Red-Black
143-82-021-00
5" to 8-1/2"
Blue-Black
143-82-021-01
3/4", 1" and 1-1/4"
8" to 14"
Green-Black
143-82-021-02
121-8
12" to 20"
Blue (2" O.D.)
143-16-021-04
18" to 30"
Green (2" O.D.)
143-16-021-05
30" to 56"
Orange (2" O.D.)
143-16-021-06
3" to 6-1/2"
Red (2" O.D.)
143-16-021-03
1-1/2", 2" and 2-1/2"
5" to 8-1/2"
Blue (2" O.D.)
143-16-021-04
121-12
8" to 14"
Green (2" O.D.)
143-16-021-05
12" to 28"
Orange (2" O.D.)
143-16-021-06
28" to 56"
Black
143-16-021-07
3" and 4"
3" to 5-1/2"
Red (3" O.D.)
121-62-021-50
121-16
4" to 7-1/2"
Blue (3" O.D.)
121-62-021-51
7" to 14"
Green (3" O.D.)
121-62-021-52
3" and 4"
12" to 28"
Orange (2" O.D.)
143-16-021-06
121-12
28" to 56"
Black
143-16-021-07
Installation and Maintenance
Model 121 Regulators
19