Type 99
7
Working Monitor
On a working monitor installation (Figure 4), the
control line of the monitoring pilot is connected
downstream of the working regulator. During
normal operation, distribution pressure causes
the monitoring pilot to stand wide open. Full pilot
supply pressure enters the working monitor pilot and
permits the working monitor regulator to control at its
intermediate pressure setting.
Open failure of the working regulator increases
distribution pressure as the working regulator goes
wide open. Intermediate pressure is then ignored by
the monitoring regulator, which controls downstream
pressure at its own pressure setting (slightly higher
than the normal control pressure).
The monitoring pilot should be upstream of the working
monitor regulator. This enables a closer setpoint
between the working regulator and the monitoring
pilot. Special Types 161AYW and 627-109 monitoring
pilots with quick-bleed operation have been designed
to give faster response to abnormal downstream
conditions. Table 5 gives the spread between normal
distribution pressure and the minimum pressure at
which the working monitor regulator can be set to take
over if the working regulator fails open.
Wide-Open Monitor
The control line of the upstream regulator is
connected downstream of the second regulator
(Figure 5), so that during normal operation the
monitoring regulator is standing wide open with the
reduction to distribution pressure being taken across
the working regulator. Only in case of open failure of
the working regulator does the wide-open monitoring
regulator take control at its slightly higher setting.
The upstream regulator must have an O-ring seal
on the valve carrier assembly. This seals off the leak
path that otherwise would let line pressure ahead of
the working regulator inlet try to close the wide-open
monitoring regulator.
Installation
!
WARNINg
Personal injury, equipment damage or
leakage due to escaping gas or bursting
of pressure containing parts might result
if this regulator is overpressured or is
installed where service conditions could
exceed the limits for which the regulator
was designed or where conditions exceed
any ratings of the adjacent piping or
piping connections. To avoid such injury
or damage, provide pressure relieving
or pressure limiting devices (as required
by the appropriate code, regulation or
standard) to prevent service conditions
from exceeding those limits.
A regulator may vent some gas to
the atmosphere in hazardous or
flammable gas service, vented gas might
accumulate and cause personal injury,
death or property damage due to fire or
explosion. vent a regulator in hazardous
gas service to a remote, safe location
away from air intakes or any hazardous
location. The vent line or stack opening
must be protected against condensation
or clogging.
Table 5.
Working Monitor Performance
MONITORINg PILOT INFORMATION
MINIMuM PRESSuRE
AT WHICH WORKINg
MONITOR REguLATOR
CAN BE SET
Construction
Spring Range
Pilot Spring
Part Number
Wire Diameter
Free Length
psig
bar
In.
mm
In.
mm
Type 161AYW with
1/8 in. / 3.2 mm orifice size and
150 psig / 10.3 bar maximum
allowable inlet pressure
3 to 12 in. w.c.
11 to 25 in. w.c.
7 to 30 mbar
27 to 62 mbar
1B653927022
1B537027052
0.105
0.114
2.67
2.90
3.750
4.312
95.2
109
3 in. w.c. / 7 mbar
over normal
distribution pressure
0.9 to 2.5
2.5 to 4.5
4.5 to 7
0.06 to 0.17
0.17 to 0.31
0.31 to 0.48
1B537127022
1B537227022
1B537327052
0.156
0.187
0.218
3.96
4.75
5.54
4.060
3.937
3.980
103
100
101
0.5 psi / 0.03 bar
over normal
distribution pressure
3/4 NPT Type 627-109 with
1/8 in. / 3.2 mm orifice size and
1000 psig / 69.0 bar maximum
inlet pressure / body rating
for ductile iron body
5 to 20
15 to 40
0.34 to 1.4
1.0 to 2.8
10B3076X012
10B3077X012
0.170
0.207
4.32
5.26
3.190
3.190
81.0
81.0
3.0 psi / 0.21 bar
over normal
distribution pressure
35 to 80
70 to 150
2.1 to 5.5
4.8 to 10.3
10B3078X012
10B3079X012
0.262
0.313
6.65
7.95
3.200
3.070
81.3
78.0
5.0 psi / 0.34 bar
over normal
distribution pressure
