Emerson 1805 Data Sheet

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

Specications

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 Coefcients

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 Orice: 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 Coefcients

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

35 0.79

Green

Silver

Blue

Red Blue

Yellow

DISTINCTIVE CONSTRUCTION FEATURES

2.25

2.13

1.94

2.94

2.50

2.31

IEC SIZING COEFFICIENTS

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

0.89

3,05 3,56 4,57

4,32 5,59 7,11

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 orice in 3/4 and 1 NPT

bodies or through registration holes in the valve guide

orice 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.

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