1805 Series Relief Valves
Bulletin 71.4:1805
October 2011
P1026
Type 1805-2
Figure 1. Typical 1805 Relief Valves
Introduction
The 1805 Series relief valves are designed for use
in farm tap applications where a safety relief valve is
needed between the rst and second stage regulators.
The 1805 Series is suitable for natural gas, air,
propane, or any operating medium that is not corrosive
to the internal parts. Relief pressures range from 5
to 125 psig / 0,34 to 8,6 bar. Maximum pressure,
including buildup, is 150 psig / 10,3 bar.
Features
• Tight Shutoff—Provided by the Nitrile (NBR)
O-ring and O-ring seat.
1805G
Type 1805-4
• Easy Maintenance—The union nut allows quick
removal of the cage assembly for trim inspection.
The valve can be back in operation in a matter
of minutes.
• Simple Adjustment—A single adjusting screw is
used to meet individual application requirements.
• Complete Venting—A closing cap is available if
all venting must be piped away.
• Sour Gas Service Capability—Optional materials
are available for applications handling sour gases.
These constructions comply with the
recommendations of the NACE International
Standards MR0175 and MR0103.
www.sherregulators.com
D100160X012
Bulletin 71.4:1805
Specications
Available Constructions
See Table 2
Body Style
Globe body
Body Sizes and End Connection Style
3/4, 1, 1-1/2, or 2 NPT
Maximum Inlet Pressure
(1)
150 psig / 10,3 bar including buildup
Relief Valve Set Pressure Ranges
See Table 1
Flow and IEC Sizing Coefcients
See Table 3
Temperature Capabilities
(1)
Construction Materials
Body: Cast Iron (all sizes) and Ductile Iron (NACE)
(3/4 and 1 NPT body sizes)
Diaphragm: Nitrile (NBR)
Valve Guide Orice: Aluminum
O-Ring Washer: Stainless steel
O-Rings: Nitrile (NBR)
O-Ring Holder: Aluminum
Diaphragm Plate: Brass
Upper Spring Seat: Plated steel
Union Nut: Ductile Iron
Vent Screen: Stainless steel
Approximate Weights
3/4 to 1 NPT bodies: 5 pounds / 2 kg
1-1/2 to 2 NPT bodies: 13 pounds / 6 kg
-20° to 150°F / -29° to 66°C
1. The pressure/temperature limits in this Bulletin or any applicable standard limitation should not be exceeded.
Table 1. Relief Valve Set Pressure Ranges
RELIEF PRESSURE RANGE
BODY SIZE, NPT
psig bar Inches mm Inches mm
SPRING PART
NUMBER
SPRING COLOR
CODE
SPRING FREE LENGTH SPRING WIRE DIAMETER
3/4 or 1
1-1/2 or 2
5 to 35
10 to 60
20 to 125
5 to 20
10 to 50
35 to 125
0,34 to 2,4
0,69 to 4,1
1,4 to 8,6
0,34 to 1,4
0,69 to 3,4
2,4 to 8,6
Table 2. Available Constructions
TYPE NUMBER
1805-2 3/4 or 1 Cast iron spring case, closing cap with 1/4 NPT vent placed over the adjusting screw
1805-3 1-1/2 or 2 Cast iron spring case, closing cap with 1/4 NPT vent placed over the adjusting screw
1805-4 3/4 or 1 Cast iron spring case
1805-5 1-1/2 or 2 Cast iron spring case
1805-7 3/4 or 1
BODY SIZE AND END
CONNECTION, NPT
Table 3. Flow and IEC Sizing Coefcients
BODY SIZE, NPT C
3/4 to 1
1-1/2 to 2 0.94 0.44
1B986027212
1B788327022
1B788427022
1D892327022
1D665927022
1E543627142
Cast iron spring case, closing cap with 1/4 NPT vent placed over the adjusting
screw, and screen in outlet
1
35 0.79
K
Green
Silver
Blue
Red
Blue
Yellow
DISTINCTIVE CONSTRUCTION FEATURES
m
2.25
2.13
1.94
2.94
2.50
2.31
IEC SIZING COEFFICIENTS
X
T
0.73 0.39
57,2
54,1
49,3
74,7
63,5
58,7
0.12
0.14
0.18
0.17
0.22
0.28
F
D
F
0.89
3,05
3,56
4,57
4,32
5,59
7,11
L
2
MXXXX
Type XXXX
UPPER
Type XXXX
Month Year
Type XXXX
INLET PRESSURE
OUTLET PRESSURE
ATMOSPHERIC PRESSURE
SPRING
SEAT
Bulletin 71.4:1805
A6671
INLET PRESSURE
OUTLET/EXHAUST PRESSURE
ATMOSPHERIC PRESSURE
Figure 2. 1805 Series Operational Schematic
Principle of Operation
See Figure 2. Relief valves respond to changes in
upstream pressure. If upstream pressure increases
and exceeds the relief valve setting, the valve will
open and allow gas to vent to the atmosphere. When
upstream pressure returns to normal level (below the
setting of the relief valve), the relief valve automatically
closes and normal system operation resumes.
In the 1805 Series relief valves, the upstream pressure
registers underneath the diaphragm. Gas reaches
the diaphragm through the space between the O-ring
holder and the valve guide orice in 3/4 and 1 NPT
bodies or through registration holes in the valve guide
orice in 1-1/2 and 2 NPT bodies.
DIAPHRAGM
HEAD
UNION NUT
O-RING
HOLDER
VALV E
SEAT
O-RING WASHER
DIAPHRAGM
VALVE GUIDE
ORIFICE
O-RING
BODY
O-RING
When the upstream pressure increases beyond the
spring setting, the force underneath the diaphragm
overcomes spring compression. The O-ring holder
moves upward, carrying the O-ring away from the
valve seat. This opens the ow line, allows gas to
ow to the atmosphere, and relieves the overpressure
condition. When upstream pressure registered on
the diaphragm decreases to a level below that of
the spring setting of the relief valve, the spring force
pushes the diaphragm plate and O-ring holder toward
the valve seat. Contact between O-ring and valve
seat prevents further ow to atmosphere.
3
Bulletin 71.4:1805
150
125
100
75
SPRING 1B788427022
50
25
bar
/
psig
150
125
100
75
50
SPRING 1B788327022
25
3/4 AND 1 NPT BODIES
125 / 8,6
50 / 3,4 SETPOINT
50 / 3,4
25 / 1,7 SETPOINT
100 / 6,9
60 / 4,1
40 / 2,8
(1)
(1)
75 / 5,2
/ 10,3
/ 8,6
/ 6,9
/ 5,2
/ 3,4
/ 1,7
/ 10,3
/ 8,6
/ 6,9
/ 5,2
/ 3,4
/ 1,7
150
125
100
75
SPRING 1E543627142
50
25
bar
/
psig
150
125
100
75
50
SPRING 1D665927022
25
1-1/2 AND 2 NPT BODIES
125 / 8,6
40 / 2,8
20 / 1,4 SETPOINT
100 / 6,9
50 / 3,4 SETPOINT
50 / 3,4
30 / 2,1
(1)
60 / 4,1
(1)
75 / 5,2
/ 10,3
/ 8,6
/ 6,9
/ 5,2
/ 3,4
/ 1,7
/ 10,3
/ 8,6
/ 6,9
/ 5,2
/ 3,4
/ 1,7
INLET PRESSURE (SETPOINT PLUS BUILDUP),
150
35 / 2,4
125
100
75
50
SPRING 1B986027212
25
B0812
1. SETPOINT IS TO BE INTERPRETED AS BUBBLE POINT
*MAXIMUM PRESSURE INCLUDING BUILDUP - 150 psig / 10,3 bar AT 150°F / 66°C.
25 / 1,7
20 / 1,4
10 / 0,69
5 / 0,34 SETPOINT
0 / 5 / 10 / 15 / 20 / 25 / 30 / 35 /
0 0,13 0,27 0,40 0,54 0,67 0,80 0,94 1,07
(1)
CAPACITY IN THOUSAND SCFH, AT 60°F AND 14.7 psia /
Nm3/h, AT 0°C AND 1,01325 bar OF 0.6 SPECIFIC GRAVITY
/ 10,3
/ 8,6
/ 6,9
/ 5,2
/ 3,4
/ 1,7
40 /
Figure 3. Relief Capacity Curves
INLET PRESSURE (SETPOINT PLUS BUILDUP),
150
125
100
20 / 1,4
5 / 0,34 SETPOINT
1,61
SPRING 1D892327022
NATURAL GAS
75
10 / 0,69
50
25
0 / 20 / 40 / 60 / 80 / 100 / 120 / 140 / 160 / 180 / 200 /
0,54 1,07
2,14
/ 10,3
/ 8,6
/ 6,9
/ 5,2
/ 3,4
/ 1,7
(1)
2,68 3,22 3,75 4,29 4,82 5,36 0
4
Figure 4. Type 1805-3 Closing Cap Sectional View
Bulletin 71.4:1805
W1258
Installation
The 1805 Series relief valves may be installed in any
position. However, the outlet connection and vents
must be protected against the entrance of rain, snow,
insects, or any other foreign material that may plug the
outlet or affect the opening and closing of the valve. If it
is necessary to pipe away the outlet, remove the outlet
screen (if one is present).
Flow through the valve must be as indicated by the ow
direction arrow on the body. For dimensional information,
see Figure 5.
Capacity Information
Natural gas relieving capacities at selected inlet
pressures (setpoint plus buildup) are given in
Figure 3. Flows are in thousands SCFH (60°F and
14.7 psia) of 0.6 specic gravity natural gas. To
determine the equivalent capacities for other gases,
multiply the capacity obtained from the curves by the
following appropriate conversion factor: 0.775 for air,
0.789 for nitrogen, 0.625 for propane, or 0.548 for
butane. For gases of other specic gravities, multiply
the given capacity by 0.775, and divide by the square
root of the appropriate specic gravity.
Overpressure
Relief pressure ratings are from 5 to 125 psig /
0,34 to 8,6 bar. The maximum inlet pressure,
including buildup, is 150 psig / 10,3 bar. System
operation within these limitations does not eliminate
the possibility of damage from external sources or
from debris in the gas line. The relief valve should
be inspected for damage regularly and after any
overpressure condition.
Universal NACE Compliance
Optional materials are available for applications
handling sour gases. These constructions comply
with the recommendations of NACE International sour
service standards.
The manufacturing processes and materials used by
Emerson assure that all products specied for sour
gas service comply with the chemical, physical, and
metallurgical requirements of NACE MR0175 and/or
NACE MR0103. Customers have the responsibility to
specify correct materials. Environmental limitations
may apply and shall be determined by the user.
Then, if capacity is desired in normal cubic meters per
hour (Nm3/h) at 0°C and 1,01325 bar, multiply values
obtained from Figure 3 by 0.0268.
5
Bulletin 71.4:1805
1/4 NPT
D
C
B
AF2211
A
Figure 5. 1805 Series Dimensional Drawings
Table 4. 1805 Series Dimensions
TYPES
1805-2
1805-4
1805-7
1805-3
/ 1
/ 1
/ 1
1805-5
1. With closing cap.
BODY SIZE AND
END CONNECTION
MATERIAL
STYLE, NPT
3/4
1
Ductile iron / NACE 3.88 / 99 1.94 / 49 1.38 / 35 6.44 / 164
Ductile iron / NACE 3.88 / 99 1.94 / 49 1.38 / 35 6.44 / 164
1-1/2 Cast iron 5.88 / 149 2.94 / 75 1.69 / 43 9.12 / 232
2 Cast iron 5.88 / 149 2.94 / 75 1.69 / 43 9.12 / 232
D
C
B
AH6967
A
TYPE 1805-4 OR 1805-5 WITHOUT CLOSING CAPTYPE 1805-2, 1805-3, OR 1805-7 WITH CLOSING CAP
DIMENSION, INCHES / mm
A B C D / max
Cast iron 3.62 / 92 1.81 / 46 1.00 / 25 6.44 / 164
Cast iron 3.62 / 92 1.81 / 46 1.00 / 25 6.44 / 164
6
Ordering Information
Please give the following information when ordering
any of the 1805 Series relief valves:
1. Type Number
2. Body Size and Material
3. Desired Relief Pressure Range
Ordering Guide
Bulletin 71.4:1805
Type (Refer to Table 2 for Construction Features)
(Select One)
1805-2***
1805-3***
1805-4**
1805-5***
1805-7***
Body Size and End Connection Style (Select One)
3/4 NPT***
1 NPT***
1-1/2 NPT**
2 NPT***
Body Material (Select One)
Cast Iron (All sizes)**
Ductile Iron (NACE) (3/4 or 1 NPT body size only)**
Regulators Quick Order Guide
Readily Available for Shipment
* * *
Allow Additional Time for Shipment
* *
Special Order, Constructed from Non-Stocked Parts. Consult your local
*
Sales Ofce for Availability.
Availability of the product being ordered is determined by the component with the
longest shipping time for the requested construction.
Relief Set Pressure Range (Select One)
3/4 or 1 NPT Body Size:
5 to 35 psig / 0,34 to 2,4 bar, Green***
10 to 60 psig / 0,69 to 4,1 bar, Silver***
20 to 125 psig / 1,4 to 8,6 bar, Blue***
1-1/2 or 2 NPT Body Size:
5 to 20 psig / 0,34 to 1,4 bar, Red***
10 to 50 psig / 0,69 to 3,4 bar, Blue***
35 to 125 psig / 2,4 to 8,6 bar, Yellow***
Replacement Parts Kit (Optional)
Yes, send one replacement parts kit to match this order
Specication Worksheet
Application:
Specic Use
Line Size
Gas Type and Specic Gravity
Gas Temperature
Relief Valve Size:
Brand of upstream regulator?
Orice size of the upstream regulator?
Wide-open coefcient of the upstream regulator?
Pressure:
Maximum Inlet Pressure (P
Minimum Inlet Pressure (P
Downstream Pressure Setting(s) (P2)
Maximum Flow (Q
max
)
Performance Required:
Accuracy Requirements?
Need for Extremely Fast Response?
Other Requirements:
1max
1min
)
)
7
Bulletin 71.4:1805
Industrial Regulators
Emerson Process Management
Regulator Technologies, Inc.
USA - Headquarters
McKinney, Texas 75069-1872, USA
Tel: +1 800 558 5853
Outside U.S. +1 972 548 3574
Asia-Pacic
Shanghai 201206, China
Tel: +86 21 2892 9000
Europe
Bologna 40013, Italy
Tel: +39 051 419 0611
Middle East and Africa
Dubai, United Arab Emirates
Tel: +971 4811 8100
For further information visit www.sherregulators.com
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a business of Emerson Process Management.
The contents of this publication are presented for informational purposes only, and while every effort has been made to ensure their accuracy, they are not to be construed as warranties or
guarantees, express or implied, regarding the products or services described herein or their use or applicability. We reserve the right to modify or improve the designs or specications of such
products at any time without notice.
Emerson Process Management does not assume responsibility for the selection, use or maintenance of any product. Responsibility for proper selection, use and maintenance of any Emerson
Process Management product remains solely with the purchaser.
Natural Gas Technologies
Emerson Process Management
Regulator Technologies, Inc.
USA - Headquarters
McKinney, Texas 75069-1872, USA
Tel: +1 800 558 5853
Outside U.S. +1 972 548 3574
Asia-Pacic
Singapore 128461, Singapore
Tel: +65 6770 8337
Europe
Bologna 40013, Italy
Tel: +39 051 419 0611
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Tel: +33 2 37 33 47 00
TESCOM
Emerson Process Management
Tescom Corporation
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Tels: +1 763 241 3238
+1 800 447 1250
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Tel: +86 21 2892 9499
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