Manual relief gas vent

A drum lid for a ventable drum has a depression formed in the surface of the lid. A vent valve is placed in the depression and extends through the lid. The valve has a valve outlet which opens into the reservoir in the lid. During venting the reservoir is filled with water and the valve stem is slowly opened. The gas escapes into the water in the reservoir in the form of bubbles. When the bubbles stop the tank is vented and the lid can be removed.

BACKGROUND OF THE INVENTION 1. Field of the Invention 
This invention relates to a manual relief gas vent which can be placed in a 
drum lid to control the pressure in the drum. 
2. Description of the Previously Published Art 
Various chemical materials have been stored in sealed drums. Some of these 
materials will produce a gas. After a period of time a gas pressure will 
build up and a problem develops as to how to safely vent the gas, 
especially when it is an explosive gas such as hydrogen. For example, when 
Raney nickel is stored in a sealed drum, there is a tendency for hydrogen 
gas to be generated which should be vented. When the drum is opened for 
use, it is necessary to carefully open the drum band and slowly pry up the 
lid to relieve any gas pressure which may exist inside. 
One solution to the problem is to use an automatic relief valve which is 
spring loaded. It could be set to vent the drum whenever the pressure was 
above a certain level such as 3 psig. There is an environmental control 
problem, however, with these valves because there is no way to control the 
gas coming off. If there are many drums in an unvented storage room on a 
hot day, the drums will all generate volumes of gas which the valves will 
automatically vent to the room. There will be no way to prevent the gas 
from accumulating in the room. 
Gas vents have been placed in drums in the past, but these vents extend 
vertically to some extent such that they extend above the rim of the drum 
when they are inserted into the bung hole of the drum lid. When the valves 
extend above the drums, it is not possible to stack the drums one on top 
of the other. 
In U.S. Pat. No. 4,688,591, a relief valve is used inside a cylindrical 
reducer housing. While effective, this device requires fabricating a 
cylindrical reducer housing for insertion in the bung hole. The 
fabrication of such a housing requires many manufacturing steps which add 
to the expense and the time involved to make the completed lid. Also, 
because the reducer housing is inserted in the lid cover through a two 
inch threaded opening, this threaded interface provides an additional 
region to seal to prevent possible leaking. 
3. Objects of the Invention 
It is an object of this invention to have a valve assembly for a drum which 
is compact and which fits in a depression in the drum lid so that it does 
not extend above the height of the drum rim. 
It is a further object of this invention to have a manually operated gas 
relief valve which can be safely operated to vent even explosive gases 
from a sealed drum, while providing a positive seal when such venting is 
prohibited. 
It is a further object of this invention to provide a sealed drum with a 
simplified cover and with better cover integrity. 
It is a further object of this invention to have a less expensive ventable 
drum cover by using a less costly reducer valve which can be simply made 
and quickly inserted into a drum cover. 
It is a further object of this invention to have a valve assembly for a 
drum where the valve outlet is protectively positioned in a reservoir 
within the drum lid. 
It is a further object of this invention to have a valve assembly where the 
valve outlet discharges into a reservoir which can be filled with water or 
other inert fluid to visually detect the flow of gas from the outlet as 
the gas bubbles into the reservoir. 
These and further objects will become apparent as the description of the 
invention proceeds. 
SUMMARY OF THE INVENTION 
An improved drum lid for a ventable drum has been developed. The lid is a 
conventional lid adapted for attachment to a drum having an upper side and 
a lower side. A novel feature is the provision of a depression in the 
surface of the lid with a bottom surface which forms a reservoir. A vent 
valve is mounted on the bottom surface of the reservoir and the valve 
extends through the bottom surface of the reservoir (i.e. through the lid) 
and it is secured to the lid on the other side. The valve is made of a 
valve stem housing which extends through the lid and it has a valve outlet 
on the upper portion of the housing which opens into the reservoir in the 
lid. A fastener, such as a nut, on the lower side of the lid to engages 
the extended portion of the valve stem housing to secure the valve to the 
lid. A further feature is a seal positioned around the valve stem housing 
to provide a liquid tight seal between the valve stem housing and the lid. 
In the preferred embodiment this is a metal washer on the upper side of 
the lid. A rotatable valve stem in the valve stem housing allows control 
of the flow of fluid within the drum through the valve stem housing and 
out the valve outlet. 
A protective cap can be placed over the drum valve assembly to keep out 
foreign matter and freezing liquids and the valve is preferably made of a 
spark resistant material. During the venting operation, the reservoir can 
be filled with an inert fluid such as water. When the valve stem is slowly 
opened, the operator can visually confirm that a gas such as hydrogen is 
venting out by watching the bubbles of vented gas rising up to the liquid 
surface. After the gas has vented out, the lid can be removed from the 
drum.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
A preferred embodiment is illustrated in the figures. The drum lid 10 shown 
in FIG. 1 has a bung opening with a cap 12 and a reservoir 14 in the drum 
lid into which is inserted the relief valve 16. 
FIG. 2 provides a side view of the lid 20 showing the depression 14 formed 
by side walls 22 and the bottom surface 24. Opening 26 in the bottom of 
the reservoir is where the valve will be mounted. The lid had a lip 28 
with a gasket 30 inside the curl of the lip. 
The valve housing 40 is illustrated in FIG. 3 and is preferably a standard, 
commercially available valve assembly which is inserted into the central 
opening 26. It is secured to the lid by a fastening nut 48 on the 
underside. A washer seal 46 is placed between the housing and the lid to 
prevent leakage. Preferably a further gas tight sealant is applied between 
the threads of the fastening nut and the threads on the bottom of the 
valve assembly and more preferably a liquid thread sealant is used. The 
upper portion of the valve housing 40 has the valve stem 42 therein and a 
valve opening 44 which opens into the reservoir 14. The valve housing is 
preferably made of a spark resistant material with nickel plated brass 
being particularly preferred. Other valve housings could be used without 
outside threads provided that sufficient engagement means are provided to 
secure the valve housing in the central opening. 
An optional weather cap 60 (not shown) made out of a plastic or rubber 
material can be inserted over the reservoir to protect the valve stem and 
the valve outlet in the reservoir from freezing liquid or foreign matter. 
The cap can fit over the top of the housing. 
To assemble the lid, the valve assembly is inserted into the opening in 
reservoir of the drum lid. A seal is provided between the valve assembly 
and the opening in the lid. The seal can be in the form of a washer which 
can be placed on either side of the lid. In FIG. 3 it is placed on the 
upper side and in FIG. 4 it is placed on the lower side. Preferably the 
washer is a metal washer since this has been found to provide the best 
seal. A fastening nut is threaded on to the bottom of the valve stem 
assembly and the nut is tightened to provide a secure seal. In a preferred 
embodiment a gas tight seal along the threads can be made by applying a 
sealant. Preferably a liquid thread sealant can be used such as Loctite 
RE/620, a retaining compound made by Loctite Corp. or its equivalent 
When it is desired to check or vent the drum, the reservoir 14 may be 
filled with water or some other inert fluid. Should there be gas under 
pressure in the drum, then when the valve stem is slightly opened the 
small venting of the gas will be very readily seen by the bubbles of gas 
coming up through the water or other inert fluid. The operator can 
continue to either vent the gas or else close the valve stem to maintain 
the gas under pressure in the drum. 
When it is desired to slowly vent the drum, the operator can open the stem 
valve and determine how much gas is coming out by observing how many 
bubbles are flowing up through the reservoir. 
A further feature of the system is that it provides a positive indication 
that the drum is in a neutral condition. If there is water in the 
reservoir and the valve stem is completely removed, then if the water 
flows down into the drum the operator knows that there is no gas pressure 
in the drum and that the valve opening into the drum is not plugged. With 
this assurance that the drum is in a neutral condition, the operator can 
then proceed to safely open the drum lid. 
The valve assembly with the liquid thread sealant has been successfully 
tested on a drum. It met the Department of Transportation's 6B Drum 
Specification (Section 178.98) for impact testing and pressure testing. 
Because the valve stem is recessed in the depression in the lid and is 
lower than the outer drum ring, it will not be harmed when the drum tips 
over or when another drum is placed on top of the first drum. 
The arrangement of the components of the drum valve assembly permit a 
variety of tools to access the parts so that the unit can be easily 
assembled. 
It is understood that the foregoing detailed description is given merely by 
way of illustration and that many variations may be made therein without 
departing from the spirit of this invention.