Chapter 3 - Tubing Connections
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MNL000297.doc
Revision 2
09/16/2016
Source System TE11
© Versum Materials, Inc. as of the revision and date shown. All rights reserved.
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3.11 Restrictive Flow Orifice (RFO) for Cylinder Valve
(Customer Requirement)
A restrictive flow orifice (RFO) must be installed in the outlet valve of any cylinder containing a
highly toxic gas or gas mix.
An RFO with a maximum orifice diameter of 0.010 inch (.254mm) must be installed in the outlet valve
of any cylinder containing pure silane or mixes containing 2% or more of Silane.
In addition to the above requirements, systems that do not have an excess flow switch installed in the
process piping line must have an RFO installed in the outlet valve of the cylinder, if the cylinder
contains a toxic gas, flammable gas, toxic gas mix or flammable gas mix that is dispensed at pressure
greater than 15 psi (1 bar).
Note: An EFS may be required by local code.
A restrictive flow orifice (RFO) may be used (at the customer’s discretion) to reduce the hazardous
exhaust treatment requirements, as an RFO will decrease the maximum potential leak rate from a full
cylinder.
Do not operate equipment without a properly
sized RFO installed in the cylinder valve.