An Improved Syphon Test Box for Gas Mains.
Year: 1893

page_text: Date of Application, 14th Aug,
4002
Accepted,
16th Sent 1803
COMPLETE SPECIFICATION.
An Improved Syphon Test Box for Gas Mains.
I, ADOLPHE BOUVIER, of 25 Avenue de Noailles Lyons in the Republic of
France, Engineer, do hereby declare the nature of this invention and in what
manner the same is to be performed to be particularly described and ascertained in
and by the following statement :--
The apparatus is shewn in the annexed drawing in which :
Figure 1 is a side elevation of the syphon test box.
Figure 2 is a vertical section on the axis of the large tube.
Figure 3 is a plan.
Figure 4 shows two of the syphon test boxes applied to a gas main.
In these figures:
A is a water tight receiver or metal box usually of cast iron two opposite sides
of which are provided with sockets a a' for connecting to the gas main.
The inner chamber of the syphon test box is divided into two parts by a central
vertical partition a² of cast iron which is situated only in the upper portion of the
chamber and does not reach to the bottom. Therefore gas entering for example
by the socket a passes freely under the partition a² and out by the socket a¹ unless
the syphon test box be filled with water to a height sufficient to cover the bottom of
the partition.
In this case the passage of the gas is stopped and the syphon test box plays the
part of a gas cock or hydraulic sluice valve. The syphon test box thus allows the
several parts of the main to be isolated one from the other.
The syphon test boxes are preferably arranged at junctions and at the lowest
points of the main so as to receive the water of condensation they therefore play the
part of ordinary syphon traps.
Upon the dome or cover of the syphon test box are three flanged cast iron
sockets BCD each provided with a pipe marked with the corresponding letter bed.
The socket B receives the iron pipe & bevelled at its lower end which dips down
to the bottom of the syphon test box and which I call the dip pipe. This dip pipe
allows the quantity of water necessary to prevent the passage of the gas, to be
introduced into the syphon test box; it is also used for removing the water
contained in the syphon test box. This emptying is performed by a hand pump
not shewn in the drawing.
The two sockets C and D arranged one to the right and the other to the left of
the central partition a² serve for the passage of the gas for testing the tightness of
the main. The syphon test box above described serves as an ordinary syphon trap
to receive the water of condensation of the gas it also serves as a junction piece
for the mains and as the hydraulic sluice valve for preventing the passage of the
gas at any time for example in case of a sudden accident, a fire or explosion, or
when any repairs to the system, replacing pipes etc. are taking place. It facilitates
the laying of new pipes; and renders the greatest service in detecting escapes of
gas in the main.
I arrange the syphon test boxes under suitable man holes E as shewn in Figure 4,
the line F F representing the ground level.
I proceed as follows for the detection of leaks. A given section of the main
comprising a portion of a street or even several adjoining streets in the same quarter,
having been isolated from the rest of the main by means of one or several syphon
test boxes previously filled with water as shown in Figure 4, I bring to the spot a
portable gasometer of usual construction mounted on wheels which is not shewn in
the drawing. Suppose that the tube a and consequently also the tube C com-
municates with the side to which the gas comes freely from the gas works under
Dim QI

page_text: the usual day time pressure of the gas for example 20 millimetres of water, and
that the tube al and consequently also the tube D communicates with the isolated
section. All the branches fed by this section are closed, thus cutting off the gas
from the houses in this section; this interruption will only last half an hour and
will only take place once or twice a year. The inlet tube of the gasometer is
caused to communicate by means of a rubber tube with the pipe c. The bell of
the gasometer rises on account of its float and is filled with gas at the pressure of
20 millimetres. When it is full the inlet pipe c is closed and the outlet tube of the
gasometer is caused to communicate with the pipe d of the syphon test box and
thus with the section to be tested. Sufficient weight is placed on the bell to give
to the gas it contains a high pressure 100 millimetres for example. This gas is
driven back under pressure into the isolated section. If this section be leaky the
bell descends with a speed proportional to the size of the leaks. I note in each
section how many litres of gas it loses per minute under the testing pressure of
100 millimetres. I thus know in figures the relative tightness of each section
under conditions which augment the sensibility of the test, and the precision of the
measurement; I know where the leaks are and what is their size; it is then easy
to repair them.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is:
1. The syphon test box substantially as described and shewn in the drawing.
2. The combination of these syphon test boxes with a gas main in order to
divide it into sections which may be completely isolated one from the other by
introducing water into the syphon test boxes.
3. The use of these syphon test boxes in combination with a gasometer for
searching under pressure for escapes of gas in all portions of the main and for
accurately measuring their size.
Dated this 14th day of August 1893.
CARPMAEL & Co.,
Agents for the Applicant.