Air Products Gasguard 250, Installation Manual

Page: 30 / 68

Section 3: Tubing Connections
Revision C: May 1997 Page 3 - 11
3.9 Helium Leak Test Port (Optional)
An optional helium leak test port may be provided on the vent header for
connection to a helium mass spectrometer. Two manual valves are included in the
assembly; MV-31 isolates the helium leak test port, and MV-32 isolates the
downstream vacuum venturi/vent system to achieve vacuums required for inboard
leak testing upstream. An access hole is provided for insertion of the vacuum hose
from the leak detector into the enclosure for hookup to the VCR port. When leak
testing is complete, manual valve MV-31 must be closed and the VCR port
capped. Manual valve, MV-32, should be opened and left open during normal
operation of the valve manifold box.
This port is for vacuum service only. Do
not connect pressurized gas to this port.
3.10 Hazardous Gas Leak Detection System
(Customer Requirement)
A gas leak detection system must be installed by the customer for all toxic gases
used in the valve manifold box. The detection points must include the interior of
the valve manifold box and the upstream source cabinet. If a leak is detected, the
system must provide a signal that will shutdown the VMB and the gas cabinet.
See specific I/O field wiring drawings provided in Section 6 of this manual.
A hydride leak detection system is highly recommended for silane and other
pyrophoric gases. Although these gases will normally ignite and burn immediately
when they leak to atmosphere, under certain conditions they can pocket and
detonate with devastating force. A hydride monitor can detect leaking silane and
shutdown the system eliminating or reducing the risk and size of explosion.