Ventilated cabinet for containing gas supply vessels

A gas cabinet for enclosing one or more compressed gas cylinders is ventilated for rapid removal of any gas leaked from the cylinders. The cabinet has a perforated plate as its floor which also serves as a fresh air inlet. Since the entire floor is used as the air inlet, the airflow through the interior of the cabinet is uniform and across the full width and depth of the cabinet, virtually eliminating dead areas or channels where leaked gas could accumulate. A tapered roof provides a smooth air handling transition to an exhaust port in the roof. The exhaust port may be connected to a plant ventilation system for removing the exhausted air from the cabinet.

FIELD OF THE INVENTION 
This invention relates generally to industrial gas supply systems and, more 
particularly, to a cabinet for housing gas cylinders or other gas vessels 
and for containing and rapidly evacuating any gas leaking therefrom. 
BACKGROUND OF THE INVENTION 
The extensive use of various highly toxic gases in the fabrication of 
electronic semiconductor devices has led to the use of gas cabinets for 
containment of the gas cylinders. Gas cabinets are substructures for the 
containment of process gas cylinders within the manufacturing plant. Such 
cabinets provide a secure, ventilated housing to safely contain both the 
cylinders and the system controls. The cabinet is designed to protect the 
cylinders and the controls from accidental damage and also to provide a 
controlled access to the gas cylinders. Although not meant to be totally 
sealed, gas cabinets are generally designed to resist leakage of gases 
into the plant atmosphere. 
In the event that a leak should occur within the cabinet, it is necessary 
that there be adequate ventilation to provide a rapid clearing of the 
atmosphere inside the cabinet. Thus, it is desirable that there be a 
complete, uniform, and continuous air sweep of the cabinet interior. 
Conventional gas cabinets utilize either front or side-mounted louvers for 
air inlet into the cabinet and an exhaust port at the top of the cabinet. 
Such an arrangement can result in channeling, dead areas, and unswept 
corners where possible leaking gas can accumulate. The conventional method 
of compensating for this problem has been to connect the cabinets to very 
high capacity ventilation systems. Such cabinets require airflows on the 
order of 350 cubic feet per minute or greater for a single cylinder 
cabinet. Such high capacity ventilation systems are, of course, more 
expensive to install and maintain. Furthermore, in a plant utilizing 
multiple cabinets in a single room, it is possible that a partial vacuum 
may be created in the room such that entry to the room is hindered. Thus, 
it is desirable to have a gas cabinet which will provide a rapid clearing 
time and thorough evacuation but utilizing lower airflows. 
SUMMARY OF THE INVENTION 
A gas cabinet according to this invention includes generally a housing 
having upright wall means comprising in the present instance three walls 
and a hinged door. ventilation is provided through a perforated floor 
plate air inlet and a tapered roof having an exhaust port. The perforated 
floor plate makes up the full width and depth of the floor surface of the 
cabinet and provides a relatively unobstructed inlet for fresh air into 
the cabinet. During normal operation, the cabinet door is closed and 
latched such that the only source of air to the cabinet is through the 
perforated floor plate. 
The gas cabinet may be provided with an elevating support base to allow 
ingress of the ambient air through the perforated floor plate or the 
entire floor plate of the cabinet may be connected to a plenum or duct for 
supplying ventilating air.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now to the drawings wherein like reference numerals indicate 
identical or corresponding elements across the several views, and in 
particular to FIG. 1, there is shown generally a gas cabinet 10 according 
to the invention. Gas cabinet 10 has sidewalls 12a and 12b and a back wall 
14 (not shown). A door 16 is attached to sidewall 12a by means of hinge 
17. Hinge 17 may consist of a continuous hinge of conventional design such 
as a piano-type hinge. 
Gas cabinet 10 also includes a tapered roof 18 having an exhaust conduit 
20. Exhaust conduit 20 is formed for connection to a plant ventilation 
system. Exhaust conduit 20 may include a damper for manually or 
automatically throttling the airflow through exhaust conduit 20. 
Gas cabinet 10 is provided with elevating feet 27a, 27b, 27c, and 27d (not 
shown). These feet 27a-d support the cabinet slightly off the floor to 
provide an air space beneath it. 
Door 16 is equipped with an observation or viewing port 30 having a 
transparent cover 31, such as a window made of wired glass or Lexan.RTM., 
and an access port 32 adjacent the viewing port having a displaceable 
panel 33 which may be opened in order to operate the controls mounted 
within cabinet 10. The panel 33 for access port 32 may be fabricated from 
Lexan.RTM. or sheet metal and is attached to the door 16 by means of a 
continuous hinge 34. A locking latch 36 is also provided to lock access 
port panel 33 in the closed position, thereby preventing unauthorized 
entry to the cabinet. Access port 32 is dimensioned and positioned such 
that under normal operation conditions as described below, no gas may 
escape through the port 32 when panel 33 is in the open position. 
Referring now to FIG. 2, there is shown generally the interior of gas 
cabinet 10. A perforated floor plate 22 extends across the full depth and 
width of gas cabinet 10 and forms the floor thereof. As shown in FIGS. 3 
and 4, perforated floor plate 22 serves not only as a floor for the gas 
cabinet 10 but also as an air inlet. Perforated floor plate 22 is 
fabricated of metal plate, such as steel, having a plurality of holes 24 
formed therein. Although the number of holes 24 in the perforated floor 
plate 22 may vary to some degree depending on particular needs, for most 
applications the perforated floor plate 22 should have substantially 42% 
open area. Cross beams 26a and 26b may be provided as additional supports 
for perforated floor plate 22 to help in supporting the weight of the gas 
cylinders. 
As previously discussed, elevating feet 27a-d are provided to support the 
cabinet 10 and to create an air space beneath it. This relationship is 
shown more clearly in FIG. 3 and a typical airflow into the gas cabinet is 
indicated by the arrows. Although FIG. 1 shows air inlets on four sides of 
the cabinet, inlets on two opposite sides only would be sufficient. The 
open area of perforated floor plate 22 may be adjusted in reference with 
the plant ventilation system capacity such that a uniform airflow is 
provided for sweeping the interior of cabinet 10. This airflow should 
generally be in the range of 66-89 feet per minute. However, for most 
applications, a flow of 77 feet per minute is adequate to provide a 
satisfactory clearing time for evacuating the cabinet. The upright wall 
means of the cabinet provide a flow passage of substantially uniform cross 
section. Tapered roof 18 provides a gradually reduced cross-sectional area 
for a smooth air handling transition into exhaust conduit 20. Since the 
present invention permits reduced airflow, the purification of the air 
exhausted through the conduit 20 to remove any entrained gas therefrom is 
facilitated. 
Referring back to FIG. 2, there is shown a three-point latching mechanism 
28 for securing door 16 in the closed position. The perimeter of door 16 
is gasketed with a conventional gasketing material 46 such as neoprene to 
provide a tight seal when door 16 is closed. 
Gas cylinders 38a and 38b are supported in cabinet 10 by means of 
adjustable support members 40 fastened to backwall 14. Cylinder support 
members 40 may comprise rack uprights, connectors and shelves, for 
example, formed of conventional structural components such as 
Unistrut.RTM.. A strap or chain 39 is utilized for tying the upper portion 
of a gas cylinder, for example 38b, to the cylinder support members 40. 
The gas controls 42 and purge panel 44 are located in the upper portion of 
gas cabinet 10 and mounted on backwall 14. 
Some of the many novel features and advantages of the present invention are 
now apparent in view of the foregoing description. For example, a gas 
cabinet 10 is provided with a perforated floor plate 22 for allowing air 
from outside the cabinet to enter across the full depth and width of the 
cabinet floor, uniformly pass through the gas cabinet 10, and be exhausted 
through exhaust port 20 at the top of the cabinet. In this manner any 
leaking gas may be rapidly removed. It will be appreciated that although a 
cabinet for housing two cylinders has been described, the novel concepts 
of the invention may also be applied to single or multiple cylinder 
cabinets. 
From the foregoing description and the accompanying drawings, it can be 
seen that the present invention provides a novel apparatus for housing gas 
cylinders and for rapidly and uniformly evacuating toxic gases leaked 
therefrom. It will be recognized by those skilled in the art that changes 
or modifications may be made to the above-described embodiment without 
departing from the broad inventive concepts of the invention. It is 
understood, therefore, that the invention is not limited to the particular 
embodiment which is disclosed but is intended to cover all modifications 
and changes which are within the scope and spirit of the invention as 
defined in the appended claims.