Emerson 1805-4 Series Manual de instrucciones - Página 3

Navegue en línea o descargue pdf Manual de instrucciones para Unidad de control Emerson 1805-4 Series. Emerson 1805-4 Series 8 páginas. Relief valves

A6671

INLET PRESSURE

OUTLET PRESSURE

ATMOSPHERIC PRESSURE

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 orifice in 3/4 and 1 NPT

bodies or through registration holes in the valve guide

UPPER

SPRING

SEAT

DIAPHRAGM

HEAD

UNION NUT

O-RING

HOLDER

O-RING WASHER

Figure 2. 1805 Series Operational Schematic

DIAPHRAGM

VALVE GUIDE

ORIFICE

O-RING

BODY

O-RING

orifice in 1-1/2 and 2 NPT bodies. When the upstream

pressure increases beyond the spring setting, the force

on the diaphragm overcomes spring compression.

The O-ring holder moves upward, carrying the O-ring

away from the valve seat. This opens the flow line,

allows gas to flow 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 flow to atmosphere.

1805 Series