Page 379 - Praxair - Specialty Gases and Equipment Reference Guide

Accessories

Excess Flow Shut-off Valves

Diffusion-Resistant, Diaphragm Seal,
Excess Flow Shut-off Valves (FS Series)
FS Series Excess Flow Shut-Off Valves are designed to automatically shut-off the
delivery of gas in a line if the flow exceeds a preset limit. They are commonly used
as a safety device to protect a system from excess flow in the event of equipment
failure or to protect personnel and property in the event of a line rupture. The capa-
bility of operating from 10 to 3500 psi allows them to be used either in high or low
pressure applications.
The Excess Flow Limit Valve is a 2-position valve. In the “Open (Reset)” position,
the valve provides a direct passage from inlet to outlet. In the other position, “Auto
Shut-Off”, the valve is set to sense the flow and automatically shuts off the passage
if the flow exceeds a preset value (flow limit). The valve will stay shut-off until it has
been reset.
Six flow ranges are offered and the actual flow shut-off value for each range is
dependent upon the operating pressure. The graph below indicates, for each
range, the relationship between operating pressure and the actual flow limit. It is
suggested that the range selected provide shut-off at 2-6 times the anticipated FS Series
flow rate to allow for short term flow surges not connected with equipment failure. Valve
Note: Piping systems, cylinders and other equipment can contribute rust or other
particulate contamination that could cause the device to fail. Therefore it is highly
recommended that all gases be filtered before they enter the FS Series Valve.
See pages E •333 and E •334 for additional information.

Standard Features Specifications Flow Range Selection Chart
n Type 316L stainless steel construction n Maximum Inlet Pressure
provides maximum corrosion resistance 3500 psig
n Elgiloy diaphragm minimizes diffusion of n Minimum Inlet Pressure
®
air into valve and maintains gas purity 10 psig
n High pressure design allows for use n Differential Pressure at Flow Limit
between a gas cylinder and the inlet to Ranges A , B, C and D: 5 psig
a pressure regulator Ranges E and F: 12 psig
n Threaded holes on bottom of valve n Operating Temperture Range
permit front panel mounting -10 F to +150 F
o
o
n Inlet and Outlet Connections
1/4" NPT female
Section E – Gas Handling Equipment
Optional Features
n High purity inlet filter provides protection n Approximate Weight
10 oz.
from particulate contamination
n Surface Finish
15-20 Ra micro inch or less
Materials Ordering Information
n Body Part Nominal Flow Limit Value for Nominal Flow Limit Value for
Type 316L stainless steel bar stock Number Nitrogen at 1000 psig Inlet Nitrogen at 30 psig Inlet
n Bonnet PRSFS-A-190 4.8 slpm 0.4 slpm
Type 316L stainless steel PRSFS-B-190 9.1 slpm 1.7 slpm
n Seat PRSFS-C-190 21.8 slpm 3.9 slpm
PCTFE
PRSFS-D-190 39.5 slpm 9.0 slpm
n Diaphragm
Elgiloy (or equivalent) PRSFS-E-190 72.3 slpm 14.4 slpm
®
PRSFS-F-190 120.6 slpm 22.5 slpm
n Spring
Hastelloy C-22 ®
n Other Metal Parts Exposed to Gas
Type 316L stainless steel

E•378 1-877-PRAXAIR www.praxairdirect.com