Data Sheet

Bulletin 71.1:630
4
To determine the wide-open capacity for relief sizing
withtheowcoefcients(C
g
), use the appropriate
procedure below.
1. Ifowiscritical(absoluteoutletpressureis
equal to or less than one-half the absolute inlet
pressure), use the equation:
Flow = (Absolute Inlet Pressure) (C
g
) (1.29)
Table 1. Maximum Inlet Pressure and Pressure Drops
Table 2. Outlet Pressure Ranges
ORIFICE SIZES
MAXIMUM ALLOWABLE
INLET PRESSURE
(1)
MAXIMUM ALLOWABLE PRESSURE DROPS
Nylon (PA) and
Polytetrauoroethylene
(PTFE) Disk
Fluorocarbon (FKM) Disk Nitrile (NBR) Disk
inches mm psig bar psig bar psig bar psig bar
1/8 and 3/16 3.2 and 4.8
1500 103
1500 103
200 13.8
600 41.4
1/4 6.4 1000 69
3/8 9.5 1000 69 500 34.5 500 34.5
1/2 13 750 51.7 250 17.2 250 17.2
1. Inlet pressure must not exceed the sum of the actual outlet pressure setting and the maximum allowable pressure drop. For example, with an outlet pressure setting of 200 psig / 13.8 bar
anda3/8-inch/9.5mmoricewithamaximumallowablepressuredropof500psid/34.5bard,themaximuminletpressureis700psig/48.3bar.
2. Nitrile (NBR) valve disks are normally furnished for pressure drops to 200 psi / 13.8 bar, differential. For better erosion resistance, Nylon (PA) valve disks are normally furnished for
higher pressuredrops.Someerosionofvalvedisksoccursatallpressuredropsduetosolidparticlesintheowstream.Therateoferosionishigherwithlargeamountsofimpuritiesin
theowstreamandwithhighpressuredrops.Valvedisksandotherregulatorpartsmustbeinspectedperiodicallyforerosionanddamageandmustbereplacedasnecessary.
REGULATOR
CONSTRUCTION
OUTLET PRESSURE
RANGE
SPRING
PART
NUMBER
SPRING
COLOR
CODE
SPRING WIRE
DIAMETER
SPRING FREE
LENGTH
MAXIMUM
OUTLET
PRESSURE
OVER
SETPOINT
(1)
MAXIMUM
EMERGENCY
OUTLET
(CASING)
PRESSURE
(4)
psig bar inches mm inches mm psig bar psig bar
Low pressure
3 to 10 0.21 to 0.69 0W019227022 Red stripe 0.23 5.84
6.0 152
20 1.4
66 4.6
8 to 20 0.55 to 1.4 0W019127022 Olive green 0.28 7.11
17 to 30 1.2 to 2.1 0W019027022 Unpainted 0.34 8.64 20
(2)
1.4
(2)
27 to 40 1.9 to 2.8 0Y066427022 Green stripe 0.36 9.14
Limited by
Maximum
Emergency
Outlet Pressure
High pressure
27 to 50 1.9 to 3.4 0W019227022 Red stripe 0.23 5.84
200 13.8
550 37.9
46 to 95 3.2 to 6.6 0W019127022 Olive green 0.28 7.11
90 to 150 6.2 to 10.3 0W019027022 Unpainted 0.34 8.64
150 to 200 10.3 to 13.8 0Y066427022 Green stripe 0.36 9.14
200 to 275 13.8 to 19.0 1J146927142 Blue stripe 0.38 9.65 6.1 155
275 to 500 19.0 to 34.5 1K370927082 Yellow stripe 0.44 11.2 6.2 157 200
(3)
13.8
(3)
1. Damage to internal parts of the regulator may occur if outlet pressure exceeds the actual pressure setting by amounts greater than those shown in this column.
2. For outlet pressure settings to 25 psig / 1.7 bar only. For pressure settings over 25 psig / 1.7 bar, outlet pressure is limited by maximum emergency outlet pressure of 45 psig / 3.1 bar.
3. For outlet pressure settings to 350 psig / 24.1 bar only. For pressure settings over 350 psig / 24.1 bar, outlet pressure is limited by maximum emergency outlet pressure of 550 psig / 37.9 bar.
4. Leakage or bursting of pressure-containing parts may occur if outlet pressure exceeds these values.
TheowdeterminedwillbeinSCFH of 0.6
specicgravitynaturalgas.ToconvertSCFH to
Nm
3
/h multiply the SCFH result by 0.0268.
2. Ifowislessthancritical(absoluteoutlet
pressure is greater than one-half the absolute
inlet pressure), use Fisher
®
’s computerized sizing
programorcontactyourlocalSalesOfce.