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Патент USA US2117829

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’ May 17, 1938.
Original Filed Jan. 26, 1934
4 ‘I
Patented May 17, 1938
Ernest H. Staber, New York, N. Y., assignor to
Socony-Vacuum Oil Company, Incorporated,
New York, N. Y., a corporation of New York
Original application January 26, 1934, Serial No.
708,351. Divided and this application August
18, 1936, Serial No. 96,687
1 Claim.
This invention is directed to improvements in
storage tanks for volatile liquids, and more par
ticularly, is directed to improvements in tanks
having a gasometer type roof.
The gasometer roof ‘tank is a tank in which the
roof has a depending skirt which dips into a
trough extending around the circumference of
the tank wall proper, either inside or outside, at
the top. This trough or well is ?lled with liquid,
10 and the tank roof is free to rise and sink in ac
cordance with the vapor pressure below. The ap
plication of excess pressure and vacuum is avoid
ed by the use of proper relief valves. -
Pressure and vacuum relief valves'of the type
‘ 15 commonly supplied have not been properly ap
plicable to the problems presented by gasometer
roof tanks.
An object of this invention is .to provide a suit
able relief valve for vacuum and pressure relief
20 for use in connection with such tanks.
The various objects and, advantages are ob
tained by means of the designs set forth in this
speci?cation and shown in the drawing attached
to and made a part hereof.
Figure 1 of this drawing shows a vertical sec
i\ tion through the relief valves, and
Figure 2 shows a partial horizontal section
‘ taken at line 1-—1 in Figure 1.
To protect the tank against vacuum and
.against pressures which might not be properly re
ilieved due to failure of operation of the roof, or
0 other causes, I make use of protective vacuum
and pressure relief valves which are set forth
diagrammatically in Figure 1.
In this ?gure,
i represents a tank, having a gasometer type roof,
formed by a top 9 and a skirt 8 dipping into a
liquid well 3-4, 28 and 29 are valve chambers
cylindrical in cross section, set up adjacent the
top of the tank wall in a convenient operating
40 location, and at a height such that they may com
municate with each other through connection 30
and with the dip ring trap on ‘the tank wall
(c1. 22_0—,85)
the liquid in the vessel 28 to a depth of say 22
to 24 inches. This gasometer ?oat 34 is made of
a light weight metal such as aluminum and its
weight is adjusted by machining so that it will
rise and vent at the proper pressure. In other
words; if the dip ring vent is designed to operate
at say 3 inches of water and it is decided that
the safety vent shall operate at ?ve inches of
water, the weight of the gasometer ?oat 34 is
such that a pressure of ?ve inches of water ex
erted upon its area will lift it, allowing gas to
escape under the bottom of its skirt. In the de
sign of valves for use on tanks working at high
pressure, heavier metals, such as steel might be
used. The skirt of this gasometer ?oat 34 is pro
vided with a plurality of ribs 35 which serve to
guide it within chamber 28. Chamber 28 is open
to the atmosphere through an ori?ce 31 at its
top, and is‘ of sufficient height to handle the full
rise of gasometer ?oat 34 and still retain it in po 20
sition to properly return to its seat when through
venting. Chamber 28 is connected to the pres
sure space within the tank by inlet 32 previously
mentioned, and by pipe 38 which terminates
within the tank at a point well up in the vapor
space near the roof. For the relief of vacuum, a
similar chamber 29, equipped with a similar in
terior pipe 39 and a similar gasometer ?oat 40, is
used, with the difference that in this case the port
4| at the bottom of chamber 29 is open to the
atmosphere, and the top of the chamber 28 is
closed to the atmosphere and in communication
with vent line 38. The gasometer ?oat 40 has
similar ribs 36 and in this case is machined so
that its weight enables it to act at the desired
vacuum, which may for example be 11/2" of wa
ter, so that when a ‘vacuum greater than this
amount exists within the tank, the gasometer
?oat 48 will rise and air admitted through 4|
will pass upward through pipe 39, the gasometer
?oat will rise to operating position,’ and the air
will then pass downward around gasometer ?oat
through connection 3i, thereby being ?lled with
40-, into chamber 29, and through pipe 38 into
the same liquid as is used in the dip ring and
being subjected automatically to the same con
ditions of dip ring level, etc. Chamber 28 is used
for the release of pressure within the tank and is
equipped with a vapor inlet 32 opening centrally
into the bottom of the chamber 28. This vapor
the vapor space of the tank.
It is noted that
this type of construction provides an unusually
long liquid seal. Any of the usual devices for
protecting a vent line against the striking back ,
of ?ame may be inserted at any point in the line
38, or if desired, may be applied to ori?ces 31 and
inlet is surrounded by a circular pipe 33 extend; ' 4i. Figure 2 shows a section through chamber 28
ing upward within chamber 28 to a level some
what greater than the level of the water over
flow on the dipring trap. Over?this central pipe
A 33 and surrounding it, there is placed a gasometer
“ ?oat 34 which extends in its normal position into
looking downwardly, and sets forth in greater de
tail the location of the ribs 36 upon the side of
the gasometer ?oat 34 and the annular relation
ship of ori?ce pipe 33' and gasometer ?oat .34. ,
Certain advantages of this form of relief valve 55
will at once be apparent. In the past, relief
valves of this type have been made so that they
’vented with a comparatively short rise and the
rapidity with which they acted resulted in a con
siderable blowing of the sealing liquid.
liquids have been used as seals ranging from mer
cury through glycerine to water and light petro
leum fractions. None of them have been emi
nently successful, yet a liquid seal valve is so
10 much more ‘desirable than one sealed by me
chanical seating of the valve, that the type has
persisted in spite of its defects. These disad
vantages 'I have avoided in several ways: First, I
have eliminated the most frequently performed
15 function, namely, that of pressure venting for
ordinary rises, and do not call upon the vent valve
‘to perform this routine venting, and reserve for
it only the duty of emergency relief, which can
only occur when excessive binding takes place
20 between roof guides and rolls, (which condition
should be immediately corrected). Secondly, I
have provided a vent valve on the gasometer
principle, having a depth comparatively great
in relation to the necessary movement of the
25 valve. For instance, in the‘pressure valve of the
example cited, I have a 22 inch depth of seal to
handle a ?ve inch pressure variation, and conse
quently considerable blowing may take place be
fore the liquid has been reduced to a depth where
it will fail to seal. Third, I may so place these 5
liquid seals that they are always in communi
cation with and in a position to be replenished by
the enormously larger reservoir of liquid in the
dip ring seal, thereby assuring an ample supply-of
liquid in seals of valves.
This case is a division of my copending appli
cation, Serial No. ‘708,351, ?led January 26, 1934. >
I claim:
In cooperation with a tank having a gasometer
type roof, a pressure relief 'valve and a vacuum .15
relief valve, each comprising a liquid seal in open
communication with the roof seal of the tank, and
in each seal a gasometer ?oat valve, each valve
of a predetermined weight ‘to enable the pre
selected pressure variation to cause it to rise 20
and vent, each valve having a skirt of relatively
great length compared to the difference in seal
ing liquid levels at its venting position.
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