ISTEC Corporation, your Flow Measurement and Control Specialist
 

ISTEC CORPORATION
Flow Measurement & Control
5 Park Lake Road, Unit 6
Sparta, NJ 07871 USA
Tel 973-383-9888
Fax 973-383-9088
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B31 Series Commercial Gas Regulator

Model B31 Series Commercial Gas Regulator Appropriate for light commercial and industrial uses where inches of water column or pounds delivery is desired such as utility services, and small to medium sized furnaces and boilers. The rapid response of the B31 is particularly well suited for applications where sudden on/off loads could cause shock problems.

 

 

FEATURES
  • Field Interchangeable Orifice
  • 27 Diaphragm Area
  • Spring-loaded Internal Relief Valve Assembly
  • Interchangeable Adjustment Spring
  • Controlled Breather Orifice
  • Wide Range of NPT Valve Body Sizes
BENEFITS
  • Smooth Control at Widely Varying Inlet Pressures
  • Lightweight
  • Easy-to-Install
  • Rugged Construction
  • Protection from Shock Damage
  • Unmatched Over-pressure Protection with Internal Monitor Plus Internal Relief (IMR) Option
  • No Special Tools Required for Outlet Pressure Adjustment
  • Compliant with ANSI and AGA-GAMA Safety Standards
B31N
A spring-loaded, self operated regulator with no internal relief (N) valve. This model can be used on low or intermediate inlet pressures where an internal relief or other type of over-pressure protection device is not required
B31R
The internal relief valve (R) version of the B31 Series. The 1" internal relief valve provides exceptional relief capacity.
B31IMN
Equipped with an Internal Monitoring (IM) device and no internal relief valve (N). This version is appropriate for applications where overpressure protection is desired without the relief of gas to the atmosphere.
B31IMR
Equipped with an Internal Monitoring (IM) device as well as a backup Internal Relief Valve (R). This version is appropriate for applications where an added level of overpressure protection is desired.
B31IMRV
Equipped with an Internal Monitoring (IM) device as well as a back-up Internal Relief Valve (R) and a Vent (V) hole in the sliding orifice. The Vent hole option allows the relief valve to "weep" gas to the atmosphere and signal monitor control in the event the main valve fails to control the downstream pressure.
B31RAS
Equipped with a Low Pressure Shut-off Valve and Internal Relief. The low- pressure shut-off valve will close if the flow through the regulator exceeds its maximum flow rate (See Capacity Table for shut-off flow values). The internal relief valve will open if the downstream pressure raises approximately 7" w.c. above the regulator's set point.
OPTION DESIGNATIONS
N
No Internal Relief
R
Internal Relief
IMN
Internal Monitor with No Internal Relief
IMR
Internal Monitor with Internal Relief
IMRV
Internal Monitor with Internal Relief and Vent
HP
All Models for Outlet Pressures > 0.5 psig
RAS
Internal Relief with Low Pressure Shutoff Valve

Valve Body High Tensile Strength Cast Iron (ASTM A-126, Class A)

Orifice Standard Aluminum or Optional Brass (ASTM B16, Alloy 360)

Internal Monitor Orifice Brass (ASTM B16, Alloy 360)

Valve Seat Buna-N or Silicone (for Temperatures below -20°F)

Valve Stem Plated Steel (AISI 1215)

Lever Pin Stainless Steel (Type 303)

Lever Zinc and Dichromate-plated Steel (AISI C1010)

Upper Diaphragm Plate Zinc and Dichromate-plated Steel (14 gage steel)

Lower Diaphragm Plate Die Cast Aluminum (ASTM B-85 Alloy SC84A)

Diaphragm Buna-N and Nylon Reinforcing Fabric

Vent Valve/Seat Neoprene

Vent Screen Stainless Steel (16 mesh)

Adjustment Ferrule Delrin; Die Cast Aluminum for HP version (ASTM CS43A)

Seal Cap Die Cast Aluminum (ASTM CS43A)

Diaphragm Case Die Cast Aluminum (ASTM B85 –Alloy SC84A)

Shipping Weight
52 lbs.
8 Regulators per Box

Correction Factors for Non-Natural Gas Applications

The B31 may be used to control gases other than natural gas. To determine the capacity of the B31 for gases other than natural gas, it will be necessary to multiply the values within the capacity tables by a correction factor. The table below lists the correction factors for some of the more common gases...


GAS TYPE SPECIFIC GRAVITY CORRECTION FACTOR (CF)

Air
1.0
0.77

Butane
2.01
0.55

Carbon Dioxide (dry)
1.52
0.63

Carbon Monoxide (dry)
0.97
0.79

Natural Gas
0.60
1.00

Nitrogen
0.97
0.79

Propane
1.53
0.63

Propane Air-mix
1.20
0.71

To calculate the Correction Factor for gases not listed in the above Table, it will be necessary to know the Specific Gravity of the Gas and use it in the formula...

Correction Factor (CF) = [SG1/SG2]1/2

Where...
SG1 = Specific Gravity of the gas in which the capacity is published.
SG2 = Specific Gravity of the gas to be controlled.


SPRING DATA – Spring Color Outlet Pressure Range*

Model B31
Part Number
Outlet Pressure Range
Models N, R, & RA
inches w.c. (mbar)
Oulet Pressure Range
Models IMN & IMR
inches w.c. (mbar)

Brown
762111
4.5 to 5.5 (11.2 to 13.7)
4.5 to 5.5 (11.2 to 13.7)
Dark Green
762117
5.0 to 6.5 (12.4 to 16.7)
5.5 to 6.0 (13.7 to 14.9)
Gray
762139
4.0 to 9.0 (9.9 to 22.4)
4.5 to 8.5 (11.2 to 21.1)
Light Green
762119
5.5 to 8.0 (11.2 to 19.9)
6.0 to 7.5 (14.9 to 18.6)
Black
762123
7.3 to 11.0 (18.1 to 27.3)
6.0 to 9.0 (14.9 to 22.4)
Blue
762127
8.0 to 12.0 (19.9 to 29.8)
7.5 to 11.5 (18.6 to 28.6)
Silver
762129
11.0 to 16.0 (27.3 to 39.8)
8.0 to 14.5 (19.9 to 36.1)
       
Model B31HP**  
PSIG (mbar)
PSIG (mbar)

Red/Grey
762025
0.75 to 1.1 (51.7 to 75.8)
0.5 to 1.0 (34.5 to 68.9)
Yellow
762131
0.9 to 1.4 (62.0 to 96.5)
1.0 to 1.5 (68.9 to 103.4)
Red
762135
1.3 to 2.0 (89.6 to 137.9)
1.3 to 1.9 (89.6 to 131.0)
White
762137
1.75 to 2.5 (121 to 172)
1.5 to 2.5 (68.9 to 172.0)

* Spring Ranges are approximate and may vary by application.
* * Warning: Springs are not interchangeable between B31 and B31HP.


OROFICE DATA – Wide Open Flow Coefficients and Maximum Pressure Data

Orifice Size K-Factor
(scfh/psi)
Maximum Operating
Inlet Pressure
All Models
Maximum
Emergency Inlet Pressure
All Models
Maximum Emergency
Outlet Pressure
(Gas Containment)
   
In. W.C. Delivery
PSIG delivery
All Outlet
In. W.C. Delivery
PSIG Delivery
   
Pressure
PSIG (Bar)
Pressure
PSIG (Bar)
Pressure
PSIG (Bar)
Pressure
PSIG (Bar)
Pressure
PSIG (Bar)

1/8"
30
125 (8.6)
175 (12.1)
300 (20.6)
18 (1.2)
60 (4.1)
1/8" IM
35
125 (8.6)
175 (12.1)
300 (20.6)
3/16"
71
125 (8.6)
175 (12.1)
300 (20.6)
3/16" IM
68
125 (8.6)
175 (12.1)
300 (20.6)
1/4"
127
125 (8.6)
125 (8.6)
300 (20.6)
1/4" IM
112
125 (8.6)
125 (8.6)
300 (20.6)
5/16"
193
100 (6.9)
100 (6.9)
150 (10.3)
5/16" IM
138
100 (6.9)
100 (6.9)
150 (10.3)
3/8"
290
65 (4.5)
60 (4.1)
150 (10.3)
1/2"
500
40 (2.8)
40 (2.8)
100 (6.9)

For wide-open orifice flow calculations use the following equations:

For P1/P2<1.89 use: For wide-open orifice flow calculation For P1/P2>1.89 use: Q = KP1/ 2
Where: P1 = absolute inlet pressure (psia) P2 = absolute outlet pressure (psia)
  Q = flow rate (scfh) K = orifice coefficient (scfh/psi)

VALVE BODY SIZES


Inlet
Outlet
Straight Body (NPT)
Angle Body (NPT)

1/2"
3/4"
1"
X
X
 

3/4"
3/4"
1"
1-1/4"
X
X
X
X
X

1"
1"
1-1/4"
X
X
X

1-1/4"
1-1/4"
X
 

X indicates that the Valve Body is available in that configuration
 

Available Vent Sizes 1/4" •  3/8" •  3/4" •  1"

Operating Temperature Range -20°F to 150°F (Silicone Seats Available below –20°F)

Other Available Option

• Seal Wire to Indicate Unapproved Tampering

• 1/8" Pipe Plug Tap on Upstream Side of Valve Body

• Tamper-Proof (Torx Head) Diaphragm Case Screws

Valve Body Type

 
A
B
C
D
E
F
R
 






3/4" & 1"
3-3/4"
2-1/8"
5-13/16"
7-13/16"
3-1/4"
4-7/8"
2-1/4"

1-1/4"
4"
2-1/8"
5-13/16"
7-13/16"
3-1/4"
4-7/8"
2-1/4"

3/4" & 1" 90° Angle Body
 
1-5/8"
5-13/16"
7-13/16"
3-1/4"
4-7/8"
2-1/4"

Model B31 Series Commercial Gas Regulator Dimensions

7" w.c. (17 mbar) Set Point Capacity Table (1" Droop)
Models N, R*
(capacities in SCFH of 0.6 S.G. gas; Base condition of 14.7 psia and 60°F)

Inlet
Pressure
(psig)
ORIFICE SIZES
1/8"
3/16"
1/4"
5/16"
3/8"
1/2"
8" w.c.
   
100
130
190
270
10" w.c.
   
110
160
240
300
12" w.c.
 
100
115
165
250
310
14" w.c.
 
110
170
190
330
440
16" w.c.
 
120
180
205
340
450
21" w.c.
 
130
230
255
410
575
24" w.c.
90
150
230
275
420
585
1
110
160
270
340
560
640
2
150
255
450
560
845
1120
3
190
325
560
770
1090
1470
5
260
470
830
1050
1400
1750
10
400
870
1470
1950
2200
2400
20
580
1020
1670
2120
2560
2650
30
700
1900
2550
2600
2680
2700
40
910
2300
2600
2630
2750
2760
50
1070
2370
2610
2670
2890
 
60
1150
2420
2700
2720
2930
 
70
1340
2500
2750
2770
   
80
1490
2510
2750
2790
   
90
1640
2510
2750
2790
   
100
1890
2520
2770
2790
   
125
2305
3420
2820
     
 
    Do not operate orifice in shaded inlet pressure area
    Inlet Pressure is too low to achieve desired outlet pressure

 

Increased Pressure Above Set Point Required for No Flow
Orifice
1/8"
3/16"
1/4"
5/16"
3/8"
1/2"
Pressure
0.3" w.c.
0.5" w.c.
0.6" w.c.
0.8" w.c.
0.9" w.c.
1.0" w.c.
 
Change in Outlet  Pressure with a 10 psig Change in Inlet Pressure
Orifice
1/8"
3/16"
1/4"
5/16"
3/8"
1/2"
Pressure
0.1" w.c.
0.2" w.c.
0.3" w.c.
0.3" w.c.
0.4" w.c.
0.5" w.c.

 

TYPICAL PERFORMANCE CURVES
7" w.c. Set Point
Type and Model B-31 R
Regulator: Inlet Size 1-1/4" NPT
Outlet Size 1-1/4" NPT
Orifice Size 1/4"
RELIEF CURVES - LEVER DISCONNECT
7" w.c. Set Point
Type and Model B-31 R
Regulator: Inlet Size 3/4" NPT
Outlet Size 1" NPT
Vent Size 1" NPT

Model B31 Series Commercial Gas Regulator Curves

14" w.c. (34 mbar) Set Point Capacity Table (2" Droop)
Models N, R*
(capacities in SCFH of 0.6 S.G. gas; Base condition of 14.7 psia and 60°F)

Inlet
Pressure
(psig)
ORIFICE SIZES
1/8"
3/16"
1/4"
5/16"
3/8"
1/2"
16" w.c.
 
90
130
170
185
260
21" w.c.
70
110
150
190
205
305
24" w.c.
80
120
160
225
225
340
1
100
145
200
240
290
410
2
120
210
300
380
475
630
3
155
270
375
500
580
820
5
210
380
560
660
800
1100
10
350
575
820
1000
118-
1500
20
510
810
1240
1300
1700
1550
30
615
1100
1500
1450
1550
1400
40
790
1350
1740
1550
1400
1300
50
1000
1530
1820
1500
1450
 
60
1100
1950
1760
1400
1350
 
70
1300
2030
1650
1350
   
80
1350
2080
1600
1300
   
90
1450
`860
1530
1275
   
100
1520
2010
1580
     
 
    Do not operate orifice in shaded inlet pressure area
    Inlet Pressure is too low to achieve desired outlet pressure

 

Increased Pressure Above Set Point Required for No Flow
Orifice
1/8"
3/16"
1/4"
5/16"
3/8"
1/2"
Pressure
0.4" w.c.
0.6" w.c.
0.7" w.c.
0.9" w.c.
0.9" w.c.
0.9" w.c.
 
Change in Outlet  Pressure with a 10 psig Change in Inlet Pressure
Orifice
1/8"
3/16"
1/4"
5/16"
3/8"
1/2"
Pressure
0.1" w.c.
0.2" w.c.
0.3" w.c.
0.4" w.c.
0.5" w.c.
0.6" w.c.

 

TYPICAL PERFORMANCE CURVES
14" w.c. Set Point
Type and Model B-31 R
Regulator: Inlet Size 3/4" NPT
Outlet Size 1" NPT
Orifice Size 3/16"
RELIEF CURVES - LEVER DISCONNECT
14" w.c. Set Point
Type and Model B-31 R
Regulator: Inlet Size 3/4" NPT
Outlet Size 1" NPT
Vent Size 1" NPT

Model B31 Series Commercial Gas Regulator Curves

1 psig (69 mbar) Set Point Capacity Table (1% Absolute Droop)
Models N, R*
(capacities in SCFH of 0.6 S.G. gas; Base condition of 14.7 psia and 60°F)

Inlet
Pressure
(psig)
ORIFICE SIZES
1/8"
3/16"
1/4"
5/16"
3/8"
1/2"
2
120
200
230
310
360
480
3
160
250
330
420
480
640
5
190
360
490
580
670
880
8
230
480
670
780
890
1260
10
310
550
730
900
1050
1370
15
410
690
980
1170
1350
1810
20
500
830
1150
1400
1600
2100
30
640
1120
1520
1760
2060
2150
40
780
1560
1920
2160
2280
2300
50
950
1610
2170
2360
2380
 
60
1100
1800
2360
2530
2550
 
75
1340
1960
2500
2680
   
85
1510
2550
2850
2810
   
100
1760
2870
3010
3100
   
 
    Do not operate orifice in shaded inlet pressure area

 

Increased Pressure Above Set Point Required for No Flow
Orifice
1/8"
3/16"
1/4"
5/16"
3/8"
1/2"
Pressure
0.04 psi
0.04 psi
0.04 psi
0.06 psi
0.06 psi
0.06 psi
 
Change in Outlet  Pressure with a 10 psig Change in Inlet Pressure
Orifice
1/8"
3/16"
1/4"
5/16"
3/8"
1/2"
Pressure
0.01 psig
0.02 psig
0.02 psig
0.03 psig
0.03 psig
0.04 psig

 

1 psig (69 mbar) Set Point Capacity Table (2% Absolute Droop)

Inlet
Pressure
(psig)
ORIFICE SIZES
1/8"
3/16"
1/4"
5/16"
3/8"
1/2"
2
150
300
420
550
660
880
3
200
370
550
730
860
1190
5
250
540
770
990
1220
1630
8
330
700
1030
1360
1640
2200
10
370
800
1200
1560
1900
2410
15
470
1030
1600
2020
2380
3100
20
550
1250
1900
2420
2920
2400
30
700
1610
2490
3080
3300
3400
40
860
1980
3100
3420
4140
4200
50
1010
2300
3500
3640
4300
 
60
1170
2680
3680
3940
4350
 
75
1400
2940
3290
4220
   
85
1600
3480
4250
4500
   
100
1820
3930
4600
4600
   
 
    Do not operate orifice in shaded inlet pressure area

 

TYPICAL PERFORMANCE CURVES
1 PSIG SET POINT
Type and Model B-31 R
Regulator: Inlet Size 3/4" NPT
Outlet Size 1" NPT
Orifice Size 3/16"
RELIEF CURVES - LEVER DISCONNECT
1 PSIG Set Point
Type and Model B-31 R
Regulator: Inlet Size 3/4" NPT
Outlet Size 1" NPT
Vent Size 1" NPT

Model B31 Series Commercial Gas Regulator Curves

 

2 psig (138 mbar) Set Point Capacity Table (1% Absolute Droop)
Models N, R*
(capacities in SCFH of 0.6 S.G. gas; Base condition of 14.7 psia and 60°F)

Inlet
Pressure
(psig)
ORIFICE SIZES
1/8"
3/16"
1/4"
5/16"
3/8"
1/2"
3
100
120
190
210
230
280
5
140
160
260
320
350
450
10
250
290
500
550
600
700
20
450
500
800
900
1000
1200
30
550
600
1000
1200
1200
1400
40
650
800
1200
1300
1500
1600
50
800
900
1400
1600
1700
 
60
900
1100
1500
1700
1700
 
70
955
1150
1600
1700
   
80
1100
1250
1700
1700
   
90
1250
1320
1700
1700
   
100
1400
1400
1700
1700
   
125
1600
1700
1700
     
 
    Do not operate orifice in shaded inlet pressure area

 

Increased Pressure Above Set Point Required for No Flow
Orifice
1/8"
3/16"
1/4"
5/16"
3/8"
1/2"
Pressure
0.04 psi
0.05 psi
0.05 psi
0.06 psi
0.06 psi
0.06 psi
 
Change in Outlet  Pressure with a 10 psig Change in Inlet Pressure
Orifice
1/8"
3/16"
1/4"
5/16"
3/8"
1/2"
Pressure
0.01 psig
0.02 psig
0.03 psig
0.04 psig
0.05 psig
0.06 psig

 

2 psig (138 mbar) Set Point Capacity Table (2% Absolute Droop)

Inlet
Pressure
(psig)
ORIFICE SIZES
1/8"
3/16"
1/4"
5/16"
3/8"
1/2"
3
120
200
320
400
480
530
5
190
330
500
600
700
850
10
280
550
800
1000
1100
1320
20
550
900
1300
1500
1800
2000
30
700
1100
1700
2000
2100
2300
40
800
1400
2000
2300
2300
2700
50
1100
1700
2400
2500
2500
 
60
1100
2000
2500
2620
2700
 
70
1125
2100
2600
2850
   
80
1300
2150
2800
2940
   
90
1475
2250
2800
3000
   
100
1700
2250
2810
3060
   
125
2100
2420
2980
     
 
    Do not operate orifice in shaded inlet pressure area

 

TYPICAL PERFORMANCE CURVES
2 PSIG SET POINT
Type and Model B-31 R
Regulator: Inlet Size 3/4" NPT
Outlet Size 1" NPT
Orifice Size 3/16"
RELIEF CURVES - LEVER DISCONNECT
2 PSIG Set Point
Type and Model B-31 R
Regulator: Inlet Size 3/4" NPT
Outlet Size 1" NPT
Vent Size 1" NPT

Model B31 Series Performance Curves

See the PDF for more information on Model B31IMR, B31IMRV, and B31IMN, Internal Monitor(IM) Principle of Operation

Download PDF VersionDownload Submittal