Apparatus and method for gas meter bypass

A gas meter bypass apparatus and method for removing a gas meter from operation for service or replacement and placing the meter back into service without interrupting the flow of gas to the user. The apparatus connects to a standard tee which is utilized on the customer side of most residential or commercial meter installations. The bypass apparatus includes a clamp assembly, a seal fitting, an isolation valve, an extraction fitting, an isolation fitting, and a flexible tube connector. The clamp assembly is used to attach the bypass apparatus to the tee. The seal fitting connects to the clamp assembly and seals between the bypass apparatus and the port of the tee where the plug is installed. The isolation valve attaches to the seal fitting. The extraction fitting attaches to the isolation valve and is used to extract and re-install the plug through the isolation valve. The isolation fitting also attaches to the isolation valve and is used to supply gas from an alternate source to the tee outlet and to seal off the flow of gas from the meter. The isolation valve is closed for switching between the extraction fitting and the isolation fitting and open for extraction and re-insertion of the plug and for extension and retraction of the isolation rod which stops the meter flow and supplies the alternate source gas to the tee outlet.

FIELD OF THE INVENTION 
This invention relates generally to gas distribution systems and more 
particularly to apparatuses and methods for the service or change out of 
gas meters without interruption of service. 
BACKGROUND OF THE INVENTION 
Although natural gas meters generally operate in a reliable and trouble 
free manner for a number of years, if service or repair is not sooner 
necessitated by damage to the meter or concerns over the accuracy of the 
meter, all must eventually be taken out of service for maintenance, 
calibration or replacement. Because of safety and accuracy concerns, 
regulatory agencies who have jurisdiction over gas utility companies, 
typically require change out of gas meters within a prescribed time 
period. Typical mandated change out periods range from 10 to 15 years. 
One of the principal concerns that gas utility company service personnel 
must address in changing out or servicing a meter is the necessity to 
accomplish the change out or service without interrupting the supply of 
gas to the residential or commercial user. If the supply of gas to the 
user is interrupted, even momentarily, pilot lights will be extinguished. 
At the very least, this then requires the service technician to enter the 
home or business and re-light the pilot lights for each of the user's 
appliances. Further, utility company policies and good safety practice 
usually require that the service technician check the user's appliances 
over for additional safety concerns, prior to re-lighting the pilots. If, 
as is often the case with residential customers and even commercial 
customers during non-business hours, a service technician must return to 
the customer's address on one or more occasions to obtain access to the 
customer's premises and appliances. Further, additional health and safety 
concerns arise in cases where property owners cannot be found for an 
extended period of time following a disruption of service. 
Because of the foregoing concerns, gas utility companies have generally 
adopted the policy that meter change out or service, for all residential 
users and most commercial users, must be accomplished without a disruption 
of service. Accordingly, a number of methods and apparatuses have been 
developed over the years to attempt to deal with this concern. However, 
all of the previously disclosed methods and apparatuses have substantial 
limitations. 
Most of the attempts to deal with this concern require special and costly 
piping, fittings, valves, and other apparatuses to be installed at each 
meter installation. Examples of this type of approach are shown in U.S. 
Pat. No. to Douglas 2,579,656, Mueller U.S. Pat. No. 3,187,570, Anderson 
U.S. Pat. No. 3,245,257, Mueller U.S. Pat. No. 3,296,861, Gilpin U.S. Pat. 
No. 3,444,724, England U.S. Pat. No. 5,042,526, Russell U.S. Pat. No. 
5,178,188, Winnie U.S. Pat. No. 5,437,300, and Winnie U.S. Pat. No. 
5,482,073. These approaches also require costly and time consuming 
re-plumbing of existing installations in order to retrofit existing 
installations with the specialized piping, fittings, valves, and other 
apparatuses. Another problem with a number of these attempts is that they 
involve the use of special apparatuses in the gas service line itself that 
restrict the flow of gas and involve potential for clogging, plugging, or 
malfunction prior to or at the time that a meter bypass is needed. For 
example, this problem is evident in the inventions described in U.S. Pat. 
No. to Russell 5,178,188, Winnie U.S. Pat. No. 5,437,300 and Winnie U.S. 
Pat. No. 5,482,073. 
Several of the attempts to deal with this concern also substantially 
increase the probability of customer bypass of the meter, allowing a theft 
of gas by the customer. For example, this is a problem with the inventions 
disclosed in U.S. Pat. No. to Douglas 2,579,656, Mueller U.S. Pat. No. 
3,187,570, Mueller U.S. Pat. No. 3,296,861, and Gilpin U.S. Pat. No. 
3,444,724. 
Also, a number of the inventions disclosed in the prior art do not provide 
an effective way of purging air from the piping and apparatuses or 
otherwise eliminating the possibility of air being introduced into the 
customer service line at the time of the meter bypass. Even minute amounts 
of air mixed with natural gas can result in a instantaneous lack of fuel 
or a minute explosion event occurring in an appliance pilot gas orifice, 
thereby extinguishing the pilot. The inventions disclosed in U.S. Pat. No. 
to Anderson 3,245,257, England U.S. Pat. No. 5,042,526, Winnie U.S. Pat. 
No. 5,437,300, and Winnie U.S. Pat. No. 5,482,073 involve the significant 
risk of this type of problem. It is, therefore, crucial that a bypass 
method or apparatus provide for the elimination of air which would 
ultimately find its way to the customer service line. 
The most widely used method and apparatus for the change out of gas meters 
in the natural gas utility industry is that disclosed in U.S. Pat. No. 
3,148,690 to Petersen. This method and apparatus has an advantage over the 
other alternatives disclosed in the prior art as identified above. This 
device is used with a standard meter installation with no special piping, 
fittings, or valves being required. 
The standard meter installation preferred by most gas utility companies 
include a shut-off valve and a pressure regulating valve on the supply 
side of the meter and a standard tee on the customer side of the meter. 
The shut-off valve is used to turn the gas on and off for customer 
service. 
The pressure regulating valve reduces the pressure from the higher main 
line pressure, which will typically ranges between 40 psi and 80 psi, to 
the lower pressure utilized in homes and business, which historically has 
ranged from the 4 oz. of pressure used for most homes to a maximum of 2 
psi for some residential and commercial users. There is a growing interest 
in utilizing higher pressure for both homes and businesses. The use of 2 
psi or higher pressures in homes allows the use of easily installed coils 
of smaller diameter tubing for gas systems rather than the larger 1/2 inch 
to 3/4 inch iron pipe historically used, which must be installed by 
traditional plumbing methods. Likewise, commercial installations are now 
utilizing pressures of 10 psi or higher, in order to reduce the size and 
cost of the piping. 
The standard tee on the customer size of the meter is the only fitting 
installed in a typical installation for use in bypassing the meter. As 
indicated above, the gas companies prefer this typical installation for 
cost and security reasons. Therefore, for a bypass apparatus to meet the 
needs of the gas utility companies, it must connect to this standard tee 
only. 
As indicated above, presently the most widely used apparatus and method for 
gas meter change out and service is that disclosed in U.S. Pat. No. 
3,148,690 to Petersen, which interfaces with the standard tee on the 
customer side of a meter. A principal problem with the Petersen device is 
that it is not adaptable to higher pressure installations. Because it 
incorporates a gas bladder which inflates as the alternate gas source is 
used to energize the customer service but must be thin and pliable enough 
to be gripped upon the tee plug, it is limited to the lower 4 oz 
applications. This device is impractical even for the 1 psi or 2 psi range 
now being utilized for many residential users. It is entirely unworkable 
for the 10 psi service pressures being utilized for some commercial 
applications. It is also obvious, from an examination of the device 
itself, that it is a cumbersome and slow method which unexpectedly meets 
with the continuing disfavor of service personnel. Gripping the plug, 
which has been pre-loosened with a wrench, by collapsing the bladder upon 
the plug by hand in the area of the tee, is awkward at the very least. The 
process of turning the plug by hand is then also slow and awkward, as the 
bladder must be collapsed and gripped upon the plug, the plug turned a 
partial revolution, and the bladder released. This process is repeated 
over and over until the plug is removed and falls to the bottom of the 
inflated bladder. Thereafter, the entire air contaminated gas contents of 
the inflated bladder must be bled from the bladder before a temporary plug 
can be advanced by hand into the tee, shutting off the gas supply from the 
meter and limiting the customer service to the alternate gas supply. After 
the change out or service work is completed, to reinstall the plug, the 
loose plug must be gripped by collapsing the bladder around the plug and 
physically moving the plug back into position to be advanced into the tee 
in the same manner that it was removed. 
It is easy to see why service personnel would be desirous of an alternative 
to the method and apparatus disclosed in the Petersen patent. However, 
that apparatus and method is the industry standard and has been used by 
most utility companies for many years. 
Therefore, a method and apparatus is needed which would provide for the 
more expeditious bypassing of a gas meter without interruption of service 
to the customer, which is compatible with standard meter installations, 
and which can be used for the full range of customer service pressures 
from 4 oz. up to 10 psi or more. The present invention provides a single 
method and apparatus for the full range of service pressures. It is fully 
compatible with standard meter installations as it attaches to the 
standard service tee. It requires no retrofit for existing meter 
installations. 
One objective of the present invention is to provide a method and apparatus 
for gas meter bypass and change out which is compatible with standard gas 
meter installations and requires no additional fittings, piping, valves, 
or other apparatuses for gas meter bypass and change out. 
A further objective of this present invention is to provide a method and 
apparatus for gas meter bypass and change out which will increase the ease 
and speed by which gas meter bypass and change out can be affected. 
A still further objective of the present invention is to provide a method 
and apparatus for gas meter bypass and change out that will work 
efficiently and effectively for the full range of service of pressures 
encountered for residential and commercial users. 
A still further objective of the present invention is provide a method and 
apparatus for gas meter bypass and change out which provides for the 
expeditious and reliable expulsion of air from the bypass apparatus, 
thereby eliminating the potential for air being mixed with the gas which 
is transmitted to the customer's appliances. 
A still further objective of the present invention is to provide a method 
and apparatus for gas meter bypass and change out which minimizes the 
potential for customer bypass of meters and the resultant gas theft. 
A still further objective of the present invention is to provide a method 
and apparatus for gas meter bypass and change out which is durable and 
reliable for continuous and high repetition use. 
A still further objective of the present invention is to provide a method 
and apparatus for gas meter bypass and change out which would be readily 
accepted by service personnel and increase their productivity. 
SUMMARY OF INVENTION 
The present invention comprises a method and apparatus which provides for a 
gas meter to be replaced or serviced without interruption of the gas 
supply to the residential or commercial customer. The apparatus of the 
present invention connects to a standard tee which is utilized on the 
customer side of most residential or commercial gas meter installations. 
The apparatus of the present invention includes a clamp assembly which is 
used to attach the apparatus to the standard tee. The front clamp plate of 
the clamp assembly has a threaded plate opening into which a seal fitting 
is threaded. Recessed from the rear end of the seal fitting, the seal 
fitting has an internal seal collar with a gasket to seal between the tee 
and the seal fitting. 
The front end of the seal fitting is threaded to mate with an isolation 
valve which has an adequate clear opening for the insertion of a plug 
extraction rod and for the insertion of an isolation rod. The seal fitting 
and the isolation valve together atmospherically isolate the plug and the 
end port of the tee where the plug is in place. 
An extraction fitting is then threaded onto the valve with the valve 
closed. The extraction cavity of the extraction fitting is dimensioned to 
accommodate a plug extractor before insertion, and to accommodate the plug 
extractor and an extracted plug and allow closure of the valve after 
extraction of the plug. After extraction of the plug and closure of the 
isolation valve, the extraction fitting is removed from the isolation 
valve. 
An isolation fitting is then threaded onto the isolation valve. The 
isolation fitting has an isolation cavity sufficiently large to permit the 
retraction of a seal tip, into the cavity so that the isolation fitting 
can be threaded onto the valve with the valve closed, and so that the seal 
tip can be retracted into the isolation fitting again after the bypass is 
completed and the valve closed before the isolation fitting is 
disconnected from the valve. 
There are two common configurations of the meter discharge piping and the 
seal tip of the isolation rod is configured differently for each of the 
configurations. If the meter discharge pipe connects to the side port of 
the tee, the isolation rod, which is a hollow pipe, provides for the 
passage of gas from an alternate gas source past the seal tip gasket to 
the discharge port of the tee. The seal tip comprises a hollow seal tip 
gasket of resilient material through which the rear end of the isolation 
rod passes, and two snap rings and a washer which hold the seal tip gasket 
in place. Grooves in the isolation rod provide a firm seat for the snap 
rings. A flexible tubing connector is attached to the front end of the 
isolation rod shaft. An isolation seal fitting is threaded onto the front 
end of the isolation fitting. The isolation seal fitting has an isolation 
seal gasket which seals the front end of the isolation fitting and seals 
around the isolation rod shaft, thereby preventing gas leakage during the 
meter bypass period, once the isolation seal fitting has been tightened 
against the front end of the isolation fitting. 
If the meter discharge pipe connects to an end port of the tee, a plug is 
removed from a port in the shaft of the isolation rod near the seal tip 
gasket and is inserted in the rear end of the isolation rod, sealing the 
rear end of the rod, and directing the gas from the alternate source out 
the isolation rod port into the tee. The seal tip gasket seals off the 
flow of gas from the meter at the inlet port of the tee which is connected 
to the meter discharge piping. The alternate source gas flows out the 
discharge port of the tee to the user. 
After meter service or change out is completed, the seal tip is retracted 
through the isolation valve into the isolation cavity and the isolation 
valve is closed. The isolation fitting is then removed from the isolation 
valve and the extraction fitting is threaded onto the isolation valve 
again with the plug extractor and the plug retracted into the extraction 
cavity. The isolation valve is then opened, the plug extractor extended 
and the plug threaded into the tee. The bypass apparatus can then be 
removed from the tee.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
Referring first to FIG. 1, a common meter installation is represented. A 
common meter installation includes inflow piping 80, a shutoff valve 78, a 
pressure reducing valve 79, a meter 2, and discharge piping 1. The 
discharge piping from the meter includes a tee 3 to which a bypass 
apparatus 4 of the present invention is attached. The bypass apparatus 
includes a clamp assembly 5 by which the bypass apparatus attaches to the 
tee. 
Referring to FIG. 7, for preferred embodiments the clamp assembly 5 is 
comprised of a front clamp plate 6, a rear clamp plate 7, clamp bolts 8, a 
clamp latch 9 and a latch bolt 10. For certain preferred embodiments, the 
front clamp plate and the rear clamp plate are triangular in shape as 
shown in FIG. 7, and are attached by threaded clamp bolts near each of the 
corners 11 of the plates. For other preferred embodiments the clamp plates 
may be square or may have other shapes and may have two or more clamp 
bolts. Under preferred embodiments, the front clamp plate has bolt holes 
12 which pass the shafts 13 of the clamp bolts and the rear clamp plate 
has threaded bolt holes 14 to receive the threaded ends of the clamp 
bolts. 
Referring to FIG. 9, the rear clamp plate 7 has a rear clamp plate slot 15 
with a slot width 16. Referring also to FIGS. 10A and 10B, this slot width 
is larger than the outside pipe diameter 17 of the rear port pipe 18 and 
is smaller than the outside port diameter 19 of the rear tee port 20. The 
rear clamp plate also has a latch groove 21 dimensioned to receive the 
latch as the clamp latch is rotated with the latch bolt 10 from an open 
position of the latch 84 to the closed position of the latch 85, the clamp 
latch is aligned with the latch groove, and the clamp latch is depressed 
into the latch groove as shown in FIG. 10B. The latch bolt hole 101 is 
dimensioned to permit the free rotation of the latch bolt and the axial 
movement 95 of the latch into and out of the latch groove as shown in 
FIGS. 10A and 10B. The latch bolt head 104 limits the axial movement of 
the latch. For some preferred embodiments the end of the latch bolt 105 is 
threaded and is secured to the clamp latch by threading the latch bolt 
into the threaded latch bolt hole 22. 
An alternative embodiment of the latch groove and latch is shown in FIG. 
13. For this embodiment, the clamp latch 9 has a latch bolt 10 near each 
end of the latch and the latch groove 21 is dimensioned to allow the latch 
to swing between an open position 84 and the up position 85 about either 
of the two latch bolts. The latch is secured in the up position by 
threading both latch bolts into the corresponding threaded latch bolt 
holes 22. 
Referring again to FIG. 7, the front clamp plate has a threaded plate 
opening 23 into which a seal fitting 24 is threaded as shown in FIG. 3. 
The inside diameter 25 of the rear end 26 of the seal fitting is larger 
than the outside diameter of the front end 27 of the tee. Recessed from 
the rear end of the seal fitting, the seal fitting has an internal seal 
collar 28, the inside diameter 29 of which is smaller than the outside 
diameter of the front end of the tee. A seal collar gasket 30 is 
positioned upon the seal collar to seal between the front end of the front 
tee port and the seal fitting as shown in FIG. 3A. 
For preferred embodiments, the front end 31 of the seal fitting is threaded 
to mate with an isolation valve 32. A ball valve is a preferred type of 
valve for the isolation valve but other types of valves may be used so 
long as an adequate clear opening 33 is provided for the insertion of a 
plug extraction rod 34 as shown in FIG. 3B and for the insertion of an 
isolation rod 37 as shown in FIG. 4B, and FIG. 5B. 
For the plug extraction configuration shown in FIG. 3A, 3B and 3C, an 
extraction fitting 40 is threaded onto the isolation valve 32 with the 
valve closed as shown in FIG. 3A. Referring also to FIG. 6, the extraction 
cavity 41 of the extraction fitting is dimensioned to accommodate the plug 
extractor 42 before insertion as shown in FIG. 3A and to accommodate the 
plug extractor and an extracted plug 43 and allow closure of the valve 
after extraction of the plug as shown in FIG. 3C. For preferred 
embodiments, the extraction rod shaft way 36 is dimensioned to fit the 
plug extraction rod 34 with a desired tolerance so that gas leakage 
through the annular space between the extraction rod shaft 82 and the 
extraction rod shaft way can be controlled while the plug is being 
extracted or re-inserted. 
For some preferred embodiments, the front end 38 of the extraction fitting 
is threaded for use of an extractor cap 39. A cap seal gasket 62 is used 
to seal off the gas leakage from the extraction rod shaft way by 
tightening the extractor cap. An extractor handle 44 which can be a wheel 
or other suitable type handle is affixed to the front end 45 of the 
extraction rod to provide for leverage in extracting and reinserting the 
plug. For preferred embodiments the seal fitting, the extraction fitting 
and the extractor cap are provided with hand grip surfaces 46, 47, 63 to 
facilitate installation of these fittings by hand, preferably without the 
use of tools. 
Referring to FIG. 6, the geometric design of the plug extractor socket 64 
can be selected to maximize the capability of the socket to grip the plug 
during extraction and re-insertion. To enhance the ability of the socket 
to retain the plug, the socket chamber 65 may be coated with an adhesive. 
Alternatively the socket chamber can be formed of a metal which is 
substantially softer than the metal in a standard plug, which inherently 
will increase the gripping ability of the socket as compared to a socket 
chamber formed of metal with a hardness comparable to the plug. 
Alternatively, the socket may be equipped with a magnetic retention element 
66 such as that shown in FIG. 11, or a mechanical locking device. The 
socket may also have slots 89 as shown in FIG. 12 to aid in the retention 
of the extracted plug. 
For the meter isolation configuration shown in FIGS. 4A and 4B and the 
configuration shown in FIGS. 5A and 5B, an isolation fitting 48 is 
threaded into the isolation valve 32. The isolation cavity 49 of the 
isolation fitting is sufficiently large to permit the retraction of the 
seal tip 51, including the seal tip gasket 52, of the isolation rod 37 
into the cavity so that the isolation fitting can be threaded into the 
valve with the valve closed as shown in FIGS. 4A and 5A, and so that the 
seal tip can be retracted into the isolation fitting again after the 
bypass is completed and the valve closed before the isolation fitting is 
disconnected from the valve. 
For the meter configuration shown in FIG. 1, the isolation rod has an 
isolation rod shaft 81 which is a hollow pipe which provides for the 
passage of gas from the alternate gas source 53 past the seal tip 51 to 
the discharge side 54 of the tee as shown in FIG. 4B. A flexible tubing 
connector 55 is attached to the front end 56 of the isolation rod shaft by 
a standard bushing 57 or other suitable fitting. An isolation seal fitting 
58 is threaded onto the front end of the isolation fitting 96. The 
isolation seal fitting has an isolation seal gasket 59 which seals the 
front end of the isolation fitting and seals around the isolation rod 
shaft, thereby preventing gas leakage during the meter bypass period, once 
the isolation seal fitting has been tightened against the front end of the 
isolation fitting. For this configuration for some preferred embodiments, 
the seal tip comprises a seal tip pipe 74 which connects to the rear end 
77 of the isolation rod, and a seal tip gasket 52 of resilient material. 
The seal tip pipe passes through the seal tip gasket to provide for 
discharge 71 of the alternate source gas from the discharge port 54 of the 
tee. For certain preferred embodiments the rear end of the isolation rod 
is internally threaded, the seal tip pipe is externally threaded and the 
seal tip pipe is secured in place by threading it into the rear end of the 
isolation rod. However, other means for connecting the seal tip pipe and 
the isolation rod can be used. A perspective view of this embodiment of 
the isolation rod and seal tip is shown in FIG. 8A. 
Referring to FIG. 8C, other embodiments of the seal tip pipe provide that 
the rear end 77 of the isolation rod passes through the seal tip gasket 
52, and the seal tip gasket is held in place by a front seal tip snap ring 
91, a seal tip washer 92, and a rear seal tip snap ring 93. The front seal 
tip snap ring is fixed in place by a front seal tip groove 90 and the rear 
seal tip snap ring is fixed in place by a rear seal tip groove 94. 
For the meter configuration shown in FIG. 2, an isolation rod plug 99 is 
removed from an isolation rod port 61 and the isolation rod plug is 
threaded into the threaded rear end 98 of the seal tip pipe as shown in 
FIG. 5A or the threaded rear end 102 of the isolation rod as shown in FIG. 
8D. Referring also to FIGS. 5A and 5B, in this configuration the inlet 
pipe 76 connected to the inlet port 60 of the tee is sealed off by the 
seal tip gasket 52 as shown in FIG. 5B, and the alternate source gas is 
discharged from the isolation rod by the isolation rod port 61 in the 
isolation rod near the rear end 77 of the isolation rod. While the 
embodiment of the seal tip shown in FIGS. 8A and 8B, and the embodiment 
shown in FIGS. 8C and 8D have only one isolation rod port, other 
embodiments may provide for a plurality of isolation rod ports which are 
plugged for use with the meter configuration shown in FIG. 1, and are 
unplugged for use with the meter configuration shown in FIG. 2. For those 
embodiments of the seal tip, the rear end of the seal tip pipe 98 as shown 
in FIG. 5A or the rear end of the isolation rod 102 as shown in FIG. 8D is 
plugged with one of the isolation rod plugs for use with the meter 
configuration shown in FIG. 2. 
The preferred embodiments of the components of the meter bypass apparatus 
described above and shown in the drawings generally utilize threaded 
connections or joints. However, flanged and bolted, screwed, mechanical 
joint and other types of connections or joints can be used for any or all 
of the connections or joints between the components. 
Embodiments of the present invention can also be used with meter 
installations having a meter bar 100 such as that shown in FIG. 14. 
Referring to FIG. 15, embodiments of the bypass apparatus for use with a 
meter bar are identical to or very similar to that used with the meter 
installation shown in FIG. 1. 
The manner in which preferred embodiments are utilized is as follows. 
Referring to FIG. 1, typically, gas meters are set with the tee 3 above 
the outlet 83 of the meter with the meter discharge piping 1 connected to 
the side port of the tee. When the meter is in service, the plug is in an 
end port opposite the end port to which the service line 97 to the user is 
connected. Referring now to FIG. 2, alternatively, the discharge piping of 
the meter may connect to an end port of the tee with the service line to 
the user connected to the side port of the tee as shown in FIG. 2. In this 
configuration the plug is in the end port of the tee opposite the port to 
which the meter discharge pipe is connected. 
For either of the configurations shown in FIG. 1 or FIG. 2, the service 
person may first loosen but not remove the plug. If the plug has been in 
place for months or years and corrosion may be present in the front end 
port, this will facilitate removal of the plug after the bypass apparatus 
is in place. 
With the clamp latch in an open position 84 as shown in FIG. 9, the clamp 
assembly 5 is fitted over the tee with the slotted rear clamp plate 
inserted over the rear port pipe 18 as shown in FIG. 7. The rear port pipe 
is connected to the rear end port 20 of the tee, which is opposite the 
front end port 103 of the tee which contains the plug. The threaded clamp 
bolts are then adjusted, squaring up the front clamp plate with the front 
end port. Then the latch is rotated to the closed position 85 as shown in 
FIG. 9, the latch is moved into the latch groove 21 as shown in FIG. 10B. 
Referring to FIG. 3A, the seal fitting 24 is then threaded into the front 
clamp plate, aligning the seal fitting with the front port. The seal 
fitting is threaded into the front clamp plate until the front end 27 of 
the tee contacts and compresses the seal collar gasket 30, and the rear 
end port of the tee presses against the rear clamp plate and the clamp 
latch, securing the clamp latch in the latch groove and the clamp assembly 
to the tee as shown in FIG. 7. The latch bolts can be threaded further 
into the rear clamp plate or loosened as needed to adjust the fit of the 
clamp assembly to the tee. 
Next, the isolation valve 32 is threaded onto the seal fitting and 
tightened in place. The seal fitting and the isolation valve together 
atmospherically isolate the plug and front port of the tee. Then the 
extraction fitting 48, with the plug extractor retracted into the 
extraction cavity, is threaded onto the isolation valve and tightened 
securely. The extractor cap 58 should then be loosened on the extraction 
fitting. 
With the isolation valve in the open position, the extraction rod handle is 
grasped and the plug extraction rod is pushed through the open isolation 
valve and the seal fitting until the socket of the plug extractor contacts 
the plug. The handle is then used to rotate the plug extractor until it 
slips over and grips the plug. The handle is then rotated counterclockwise 
to remove the plug from the tee. 
As the plug is removed from the tee, gas enters the seal fitting, the 
isolation valve and the extraction fitting under pressure, and the gas is 
mixed with the air present inside those components. The extractor cap 
should be in a loosened position at the time that the plug is removed from 
the tee to allow all this impure gas, the gas mixed with air, to be purged 
from the seal fitting, the isolation valve and the extraction fitting 
through the front of the extraction fitting past the extractor cap seal 
gasket and the extractor cap. When the service person is satisfied that 
all the impure gas has been purged, the extractor cap can be tightened 
onto the extraction fitting, compressing the cap seal gasket against the 
plug extraction rod, thereby preventing further gas leakage through the 
annular space between the plug extraction rod shaft and the extraction rod 
shaft way. The plug extractor with the plug gripped therein is then 
retracted through the open isolation valve into the extraction cavity and 
the isolation valve is closed. The extraction fitting is then threaded off 
the isolation valve. 
With the seal tip and seal tip gasket retracted into the isolation cavity, 
the isolation fitting is loosely threaded onto the isolation valve as 
shown in FIG. 4A. With the isolation seal fitting and the isolator cap 
also in a loosened condition, the flow of gas 70 from the alternate gas 
source is started. The pressure of the gas supplied by the alternate gas 
source must be adjusted to roughly match the pressure of the gas coming 
from the meter 68, so that pilot lights, furnaces and appliances are not 
disrupted by fluctuations in the gas pressure at the time of switch over 
to the alternate gas source. Again, air in the flexible tubing, the 
isolation rod, and the isolation cavity is mixed with gas and must be 
purged. The impure gas is allowed to leak out of the joint between the 
isolation fitting and the isolation valve and the joint between the 
isolation fitting and the isolation seal fitting. The flow of gas from the 
alternate gas source is continued until the service person is satisfied 
that all the impure gas has been purged, and the isolation fitting and the 
isolation seal fitting are then each tightened into place. This compresses 
the isolation seal gasket and seals the front end of the isolation fitting 
and seals around the isolation rod shaft, thereby preventing further gas 
leakage. The isolation valve is then opened. 
The isolation rod is advanced through the open isolation valve, the seal 
fitting, and the front port of the tee, until the seal tip gasket mates 
with the rear port pipe. The outside seal tip gasket diameter 86 is 
smaller than the inside diameter of the front end port of the tee and is 
larger than the inside diameter of the rear port pipe. The seal tip gasket 
will therefore pass through the front port of the tee and seal off the 
rear port pipe, stopping the normal flow of gas from the meter 68 and the 
normal flow of gas from the tee 69. For the meter configuration shown in 
FIG. 1, if the pressure of the gas from the alternate source is slightly 
less than the pressure of the gas coming from the meter, the pressure 
differential will help keep the seal tip gasket seated so long as the 
meter is pressurized. When the meter shutoff valve is closed, 
de-pressurizing the meter, a means is necessary to keep the seal tip 
gasket seated. The isolation seal fitting is tightened after the seal tip 
gasket is seated in the rear port pipe and this holds the isolation rod 
firmly in place despite the pressure which tends to unseat the seal tip 
gasket and further seals off the leakage of gas from the bypass apparatus. 
For the meter configuration shown in FIG. 2 and the isolation fitting 
configuration shown in FIG. 5B, if the alternate source pressure is 
adjusted to slightly greater than the pressure of the gas normally flowing 
from the meter 72, the pressure of the alternate source gas 70 will tend 
to keep the seal tip gasket seated whether the meter shutoff valve is open 
or closed. However, to prevent accidental unseating of the seal tip gasket 
and a resultant loss of pressure, the isolation seal fitting should be 
tightened in this configuration also after the seal tip gasket has been 
seated in place. 
The customer service then is being supplied from the alternate gas source, 
and the normal flow of gas 72 from the meter and from the tee 73 is 
blocked. The meter shutoff valve 78 may then be closed and the meter can 
be serviced or replaced. 
When the service personnel have finished the service or change-out of the 
meter and are ready to place the meter in service, the meter must first be 
purged. This is accomplished by tightening the inlet meter nut 87 onto the 
meter but only loosely threading the outlet meter nut 88 onto the meter. 
The main gas supply is then turned on until the meter is fully purged. 
Then the outlet meter nut is tightened. 
Next, for the meter installation configuration shown in FIG. 1, while the 
isolation rod is held firmly in place by a service person, the isolation 
seal fitting is loosened, allowing the main gas supply to purge the meter 
discharge piping, the tee, the seal fitting, the isolation valve, and the 
isolation fitting. When the service person is satisfied that the meter, 
the piping and the bypass apparatus are sufficiently purged, the seal tip 
gasket is unseated from the rear port pipe, the seal tip gasket and seal 
tip are retracted through the seal fitting and the isolation valve into 
the isolation cavity, and the isolation valve is closed. The alternate gas 
source is then shut off and the isolation fitting is screwed off the 
isolation valve. 
Next an approved sealant is normally placed on the plug threads, and the 
extraction fitting, with the plug extractor and the gripped plug retracted 
into the extraction cavity, is threaded onto the isolation valve. With the 
extractor cap loosened, the isolation valve is opened. After the 
extraction fitting has been fully purged, the extractor cap is tightened 
until the gas no longer escapes. The plug extractor and the plug are 
advanced through the isolation valve and the seal fitting to contact the 
front end of the tee. The extraction rod handle is rotated 
counterclockwise one full turn. Then the handle is rotated slowly, 
ensuring that the plug is threading correctly into the front port of the 
tee. The plug is advanced until it fits snugly in the tee. The plug 
extractor is then loosened from the plug and retracted into the extraction 
cavity. 
Under preferred embodiments of the method of the present invention, the 
isolation valve is then closed and the extraction fitting is screwed off 
of the isolation valve. The isolation valve is then opened partially. If 
gas is still leaking at a rate which indicates that the plug may not have 
been reinserted correctly, the isolation valve is closed and the plug 
extraction fitting threaded back onto the isolation valve. The plug is 
then removed and reinserted as needed to accomplish a correct 
reinstallation of the plug. Once the leakage from the reinserted plug is 
stopped or is deemed acceptable to the service person, the isolation valve 
is screwed off of the seal fitting and the seal fitting is threaded out of 
the front clamp plate. The clamp assembly is then loosened and removed 
from the tee. The plug can then be further tightened into the tee with a 
wrench as desired to stop any remaining leakage. 
Other embodiments of the invention and other variations and modifications 
of the embodiments described above will be obvious to a person skilled in 
the art. Therefore, the foregoing is intended to be merely illustrative of 
the invention and the invention is limited only by the following claims.