Types 1098-EGR and 1098H-EGR
4
Principle of Operation
The pilot-operated Types 1098-EGR and 1098H-EGR
regulators both use inlet pressure as the operating
medium, which is reduced through pilot operation to load
the actuator diaphragm. Outlet or downstream pressure
opposes loading pressure in the actuator and also
opposes the pilot control spring. The Type 1098-EGR
regulator operation schematic is shown in Figure 2.
In operation, assume that outlet pressure is below
the pilot control setting. Control spring force on the
pilot diaphragm opens the pilot valve plug providing
additional loading pressure to the actuator diaphragm.
This loading pressure forces the actuator stem
forward, opening the main valve plug via a bump
connection. The upward motion of the plug allows gas
to flow through the cage into the downstream system.
When downstream demand has been satisfied, outlet
pressure tends to increase, acting on the pilot and
actuator diaphragms. This pressure exceeds the pilot
control spring setting, moving the pilot diaphragm
away and letting the valve plug spring (Type 6351,
61 Series, or Type Y600AM pilots) or bellows
(Types 6352 through 6354M pilots) close the pilot
valve plug (unbalanced in the Type 6351 or 61 Series
pilots but balanced in the Types 6352 through
6354M pilots). Excess loading pressure on the
actuator diaphragm escapes downstream through the
bleed hole (Type 6351 pilot), bleed orifice (61 Series
pilot), restriction (Types 6352 through 6354M pilots), or
fixed restrictor (Type Y600AM pilot).
Reduced actuator loading pressure permits the main
valve to close. The combination of main valve spring
force and valve plug imbalance provides positive valve
plug shutoff against the port and upper seals.
To protect the Type 1098 or 1098H actuator diaphragm
from excessive differential pressure, the 6300 Series
pilots have a relief valve that allows loading pressure
to bleed downstream at approximately 25 psig / 1,7 bar
differential across the actuator diaphragm. An external
relief valve (Type 1806) is required when differential is
higher than 25 psi / 1,7 bar or when using the
61 Series or Y600AM pilots.
40 psi / 2,8 bar Relief Valve
A mounting assembly for a 40 psi / 2,8 bar differential
relief valve is available for the Type 1098-EGR. The
standard 25 psi / 1,7 bar differential relief valve
construction is integrally mounted between the loading
and downstream pressures in the 6351 through
6354 Series regulating pilots. Both differential relief
valves protect the main regulator diaphragm from
damage that may occur from too high differential
between the loading pressure and downstream pressure.
The 40 psi / 2,8 bar differential relief valve construction
is designed specifically for the red main valve spring
selection in the NPS 6 / DN 150 Type 1098-EGR-6354
with the size 30 actuator. This construction uses the
Type 1806H relief valve (with a setting of 40 psi / 2,8 bar)
to relieve excess loading pressure and does not interfere
with the normal operation of the regulator.
Table 5.
Supply Pressure Settings Required for the Type 95H Regulator
BODy SIzE
TyPE EgR
SPRINg COlOR
SuPPly PRESSuRE
Type y600AM Spring Color
NPS
DN
Red
unpainted
yellow
green
light Blue
Black
psig
bar
psig
bar
psig
bar
psig
bar
psig
bar
psig
bar
1
25
Green
Blue
Red
6
7
8
0,41
0,48
0,55
6
7
8
0,41
0,48
0,55
7
8
9
0,48
0,55
0,62
8
10
11
0,55
0,69
0,76
11
13
14
0,76
0,90
0,97
13
14
15
0,90
0,97
1,0
2
50
Green
Blue
Red
6
8
13
0,41
0,55
0,90
6
8
13
0,41
0,55
0,90
7
9
14
0,48
0,62
0,97
9
11
16
0,62
0,76
1,1
12
14
19
0,83
0,97
1,3
13
15
20
0,90
1,0
1,4
3
80
Green
Blue
Red
7
9
14
0,48
0,62
0,97
7
9
14
0,48
0,62
0,97
8
10
15
0,55
0,69
1,0
10
12
17
0,69
0,83
1,2
13
15
20
0,90
1,0
1,4
14
16
21
0,97
1,1
1,5
4
100
Green
Blue
Red
8
11
16
0,55
0,76
1,1
8
11
16
0,55
0,76
1,1
9
12
17
0,62
0,83
1,2
11
14
19
0,76
0,97
1,3
14
17
22
0,97
1,2
1,5
15
18
23
1,0
1,2
1,6
6 or 8 x 6
150 or
200 x 150
Green
Blue
Red
13
17
22
0,90
1,2
1,5
13
17
22
0,90
1,2
1,5
14
18
23
0,97
1,2
1,6
15
20
25
1,0
1,4
1,7
18
23
28
1,2
1,6
1,9
20
24
29
1,4
1,7
2,0
1. The pressures shown in the table are the minimum supply pressures required by the pilot. If the inlet pressure is less than shown, an external pilot supply is necessary.
