WO2002004843A2

WO2002004843A2 - Seal dam apparatus and method for electrical conduit

Info

Publication number: WO2002004843A2
Application number: PCT/US2001/021914
Authority: WO
Inventors: Mathew D. Southwick
Original assignee: Southwick Mathew D
Priority date: 2000-07-11
Filing date: 2001-07-10
Publication date: 2002-01-17
Also published as: WO2002004843A3; AU2001280518A1; AU2001280518A8

Abstract

A multi-wire conduit dam (3) of resilient material cut or molded in the form of a cylindrical disk (4), to snugly fit the interior diameter of a vertical electrical conduit seal-off fitting (1 ), wherein the dam (3) has wire orfices (6) having an inside diameter (8), wherein electrical wires (2) pass through.

Description

SEAL DAM APPARATUS AND METHOD FOR ELECTRICAL CONDUIT

FIELD OF THE INVENTION

This invention relates to apparatuses and methods for sealing electrical conduits

to prevent flammable or explosive gases and liquids from passing through the conduits,

and in particular relates to apparatuses and methods for spacing electrical conductors and

damming electrical conduit for the pouring and setting of a conduit seal.

BACKGROUND OF THE INVENTION

The need for preventing the migration of flammable and explosive gases and

liquids inside an electrical conduit to potential ignition sources, such as electrical

junction and circuit breaker boxes, is longstanding and the numbers and types of

installations where this is necessary continues to increase. Electrical codes in the United States and other countries typically require a seal of time-curing sealant material be

poured in a seal-off fitting which is located in electrical conduit, to prevent passage of

flammable or explosive gases and liquids through the conduit at gas stations, petroleum

bulk plants, petroleum refineries, factories, granaries and similar installations. The time-

curing sealant material is commonly a slurry type of cementious material referred to as

"chico". For some conduit configurations, it is poured on a horizontal dam in a seal-off

fitting designed for vertical conduit installations and for others it is poured between two

vertical dams in a seal-off fitting designed for horizontal conduit installations..

Each of the wires must be separated by a specified minimum clearance in order

for the sealant material to seal completely around each wire. The sealant material

adheres to each wire and to the interior surface of the seal-off fitting while solidifying to

form an impervious barrier to the passage of gases and liquids through the conduit to an

ignition source. A number of prior art devices and methods have been developed to provide a dam

for the sealant material. One of the common deficiencies noted with the prior art devices

and methods is a tendency for the devices to allow sealant material to seep beyond the

dam. Another of the common deficiencies is the time and consequent expense of

preparing a dam to adequately hold the sealant material. Another common deficiency is

an inability or difficulty in establishing or maintaining a desired or required clearance

between the wires.

The device disclosed in U.S. Patent No. 4,723,055 to Bisker attempts to deal with

each of the foregoing concerns. This device comprises a molded strip of closed cell

sponge rubber such as neoprene or equivalent with grooves or notches on one side,

similar in appearance to a timing belt. Each wire is placed in a groove and covered with

an adhesive tape which, when wound into a bundle, adheres to and dams the cylindrical

conduit seal-off fitting. The strip of neoprene can be trimmed or cut to the proper length

for application in smaller conduits. This device is cumbersome and difficult to use, and

is not tailored to a specific number of wires. Typically, there will be notches or grooves

which do not contain wires. While the device is purportedly designed to self seal these

unused notches or grooves by contact between the unused notches or grooves and the

successive belt roll, the penetrations are still present and constitute a potential for leakage

of the sealant material. There is also limited flexibility in the size of wire that can be

used with a specific groove size and the circumferential and radial spacing of adjacent

wires is fixed for each device. This device would also be relatively expense to

manufacture. The deficiencies noted for this device are most likely the reason that it

apparently has not met with commercial success since the issue date for the patent in

1988. The failure of prior art devices to effectively meet the requirements of these

conduit installations is clearly manifested by the method which is used almost

exclusively in the industry. A loose fibrous material is typically hand packed through the

access opening on the seal-off fittings around the wire bundle and between each wire.

The fibrous material is packed between the wire bundle and the inside surface of the

conduit, and between each of the wires through the use of the installer's fingers and hand

tools. With the very confined access, especially for the smaller conduits, it is very

difficult to get the packing material in place as needed to provide the minimum clearance

between the wires and to provide a leak free dam for the sealant material. Uniformity in

the thickness and density of the dam is very difficult to achieve, as is getting a proper

seal and a proper spacing between the wires. The placement of this fibrous material must

be accomplished with the wires in place Yet, this is the standard method in use in the

industry and it is used because no practical alternative has been developed before the

present invention. One object of the present invention is to provide a sealant dam which is matched

to the diameter of the conduit seal-off fitting and is matched to the size and number of

wires passing through the conduit.

A further object of the present invention is to provide a sealant dam that

maintains a minimum desired or required clearance between the wires.

A still further object of the present invention is to provide a sealant dam that will

reliably support the uncured sealant material and will reliably block leakage of the

sealant material while that material solidifies.

A still further object of the present invention is to provide a sealant dam that is

very economical. A still further object of the present invention is to provide a sealant dam that is

easy to use and requires less time to install.

A still further object of the present invention is to provide a sealant dam that can

be fitted on each of the wires of the wire bundle before being fitted in the conduit,

thereby greatly simplifying installation.

SUMMARY OF THE INVENTION

The conduit sealant dam ("sealant dam") of the present invention is comprised of

a cylindrical disk of resilient material, such as polyethylene foam, with one or more wire

orifices for the passage of electrical wires through the dam. The inventor has found that

polyethylene foam with a density of approximately four pounds per cubic foot works

particularly well for the sealant dam, but many other types of resilient material may be

used. The thickness of the sealant dam will depend on the diameter of the conduit and

the material used for the sealant dam. With the four pounds per cubic foot polyethylene

foam, the inventor has found that a sealant dam thickness approximately equal to one-

half the diameter of the conduit works particularly well.

The sealant dam can be manufactured to the required dimensions by molding,

cutting, punching or other methods known to persons skilled in the art. Alternatively the

sealant dam may be punched in the desired diameter by the installer from a bat of

resilient material of the required thickness.

The wire orifices can be molded, punched or heat penetrated into the sealant dam,

or may be formed in other ways known to persons skilled in the art. The number of wire

orifices and the diameter of the wire orifices are selected based upon the number and

diameter of the wires to be passed and the minimum clearance required between the

wires. Friction between the wires and the inside surface of the respective wire orifices is a primary stabilizing force used to hold the sealant dam in place in the seal-off fitting as

the sealant is poured and cured and therefore the diameter of the wire orifices is selected

to provide a tight fit with the wires being passed. The wire orifices may be created by the

user by passing a heated probe at a temperature consistent with melting the sealant dam

material.

Some additional stabilizing force is provided by the friction between the sealant

dam and the inside surface of the seal-off fitting and therefore the diameter of the sealant

dam must be selected to provide for a tight fit between the sealant dam and the inside

surface of the seal-off fitting. This is also important to prevent leakage of the sealant

material as it cures.

Electrical conduit installations requiring gas and liquid migration prevention will

incorporate one or more seal-off fittings. As electrical wires are brought through the

electrical conduit they are extended through the seal-off fitting. A sealant dam of the

present invention having a selected diameter and a selected number of wire orifices of a

selected diameter is slipped onto the wires and slid into the seal-off fitting to the correct position for receiving the sealant material slurry. When the sealant material cures, the

seal is complete.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1. A side perspective elevation view of a vertical electrical conduit seal- ^■

off fitting with wires passing and a preferred embodiment of the present invention being

inserted on the wires.

FIG. 2. A side perspective elevation view of a vertical electrical conduit seal-

off fitting with wires passing and a preferred embodiment of the present invention in the

installation position and sealant material placed thereon. FIG. 3. A side perspective view of a preferred embodiment of the present invention with a heated probe inserted to form a wire orifice.

FIG. 4. A side perspective elevation view of a horizontal electrical conduit seal- off fitting with wires passing and a pair of sealant dams of the present invention with a sealant dam in each of the respective installation positions and sealant material placed therein.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Referring first to FIG. 1, a typical vertical electrical conduit seal-off fitting 1 is illustrated with insulated electrical wires 2 passing through. A preferred embodiment of

the sealant dam 3 of the present invention, which is constructed of resilient material in

the form of a cylindrical disk 4, is shown inserted on the wires to the pre-installation

position 5. Each of the wires is passed through a respective wire orifice 6 in the sealant

dam, the wire orifices being alined with the axis 7 of the cylindrical disk. Each of the

wire orifices has an inside diameter 8 which provides for a tight fit on the wire passing through the wire orifice. If the sealant dam is pre-manufactured with a specific number of wire orifices, then a dam will be selected with the required number of orifices.

Alternatively, the wire orifices may be formed by the installer, using the method of the present invention.

The sealant dam is then slid along the wires from the pre-installation position 5

shown in Fig. 1 to the installation position 9 shown on Fig. 2. The sealant dam diameter

10 is selected to fit tightly against the inside surface 11 of the seal-off fitting. Also, friction between the outside surface of the wires and the inside surface of the respective orifices is a major force in retaining the sealant dam in the installation position. Time- curing sealant material 13 is poured through the access portal 14 upon the sealant dam in

a desired thickness 15. The tight fit between the outside surface of the sealant dam and

the inside surface of the seal off fitting and the tight fit between the inside surface of the

wire orifices and the outside surface of the wires minimizes problems with leakage of the sealant material past the dam.

The cylindrical disk of the sealant dam may be manufactured by molding, cutting

or punching or by some other process known to persons skilled in the art, or may be

formed by the installer through the use of a common circular punch of the desired

diameter by punching the disk from a bat of the selected resilient material of the desired

thickness. Similarly, the wire orifices can be formed during the manufacturing process

by molding, punching or by other methods known to persons skilled in the art, or maybe

formed by the installer at the time of installation by punching or by other methods known

to person skilled in the arts. However, the method of the present invention illustrated in Fig. 3 for forming wire orifices in the sealant dam has been found by the present inventor

to be superior to known methods.

Referring to Fig. 3, a probe 16 which is heated to a temperature above the melting

temperature of the resilient material from which the disk is made is inserted through the

disk to create a wire orifice with a desired diameter 17 at a location 18 desired by the

installer, with the wire orifice aligned with the axis 7 of the sealant dam. This process is

repeated until the desired number of wire orifices have been created in the sealant dam,

matching the number of wires. Referring also again to Fig. 1, the spacing 20 of the wire

orifices is controlled by the installer to provide for minimum desired clearance 21

between the wires.

Fig. 4 illustrates an alternative embodiment of the present invention which is utilized for a conduit installation where a horizontal seal-off fitting 22 is required. For

this embodiment, two sealant dams, a first sealant dam 23 and a second sealant dam 24

are utilized.

If the seal-off fitting is not already in place in the conduit, each of the wires is

passed through a respective wire orifice 25 of the first sealant dam prior to passing the

wires through the horizontal seal-off fitting. The wires are then passed through the first

wire portal 26 of the seal-off fitting and the first sealant dam is fitted through the first

wire portal into the first installation position 27. Each of the wires is then inserted into a

respective wire orifice 28 of the second sealant dam, and the second sealant dam is slid

along the wires through the second wire portal 29 of the seal-off fitting into the second

installation position 30.

Alternatively, if the seal-off fitting is already in place in the conduit, each of the

wires is passed through a respective wire orifice 25 of the first sealant dam and the first

sealant dam is slid along the wires through the second wire portal 29 of the seal-off

fitting and through the seal-off fitting space 33 to the first installation position 27. Each

of the wires is then inserted into a respective wire orifice 28 of the second sealant dam,

and the second sealant dam is slid along the wires through the second wire portal 29 of

the seal-off fitting into the second installation position 30.

Sealant material 31 can then be poured through the access portal 32, filling the

space 33 in the seal-off fitting between the first sealant dam and the second sealant dam.

The friction between the outside surfaces 34, 35 of the respective sealant dams and the

interior surface of the seal-off fitting 36 and friction between the outside surface of the

wires 37 and the inside surface of the wire orifices 38 of the respective sealant dams hold the dams in position as the sealant material is poured into the seal off fitting and allowed

to cure.

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.

Claims

CLAIMSWhat is claimed is:

1. Apparatus for forming and supporting time curing sealant material in a

electrical conduit seal-off fitting, the sealant material being formed and cured to prevent

the migration of flammable or explosive gases or liquids along the electrical conduit to a

potential ignition source, the apparatus comprising one or more sealant dams, each

sealant dam being in the form of a cylindrical disk of resilient material having one or

more wire orifices through the disk, the orifices being aligned with the axis of the disk

and the orifices being separated to provide a desired clearance between the respective

wires which are to be passed through the orifices, the diameter of each orifice providing

for a tight fit between the inside surface of the orifice and the outside surface of the respective wire passing through the orifice, and the diameter of the disk providing for a

tight fit between the disk and the inside surface of the conduit seal-off fitting.

2. Apparatus as recited in Claim 1 wherein the resilient material is

polyethylene foam.

3. Apparatus as recited in Claim 2 wherein the polyethylene foam has a

density of approximately four pounds per cubic foot.

4. Apparatus as recited in Claim 1 wherein the wire orifices of each disk are

molded into the disk at the time that the disk is made.

5. Apparatus as recited in Claim 1 wherein the wire orifices of each disk are

punched into the disk.

6. Apparatus as recited in Claim 1 wherein the wire orifices of each disk are

formed by passing a heated probe through the disk at each position that an orifice is desired.

7. Apparatus as recited in claim 1 wherein the seal-off fitting is a vertical

seal-off fitting and the apparatus comprises one sealant dam.

8. Apparatus as recited in claim 1 wherein the seal-off fitting is a horizontal

seal-off fitting and the apparatus comprises two sealant dams.

9.. A sealant dam for forming and supporting time curing sealant material in

a vertical electrical conduit seal-off fitting, the sealant material being formed to prevent

potential ignition source, the sealant dam comprising a cylindrical disk of resilient

material having one or more wire orifices through the disk, the orifices being aligned

with the axis of the disk and the orifices being separated to provide a desired clearance

between the respective wires which are to be passed through the orifices, the diameter of

each orifice providing for a tight fit between the inside surface of the orifice and the

outside surface of the respective wire passing through the orifice, and the diameter of the

disk providing for a tight fit between the disk and the inside surface of the conduit seal-

off fitting.

10. Sealant dam as recited in Claim 9 wherein the resilient material is

polyethylene foam.

11. Sealant dam as recited in Claim 10 wherein the polyethylene foam has a

density of approximately four pounds per cubic foot.

12. Sealant dam as recited in Claim 9 wherein the wire orifices are molded

into the disk at the time that the disk is made.

13. Sealant dam as recited in Claim 9 wherein the wire orifices are punched

into the disk.

14. Sealant dam as recited in Claim 9 wherein the wire orifices are formed by passing a heated probe through the disk at each position that a orifice is desired.

15. A pair of sealant dams for forming and supporting a time curing sealant

material in a horizontal electrical conduit seal-off fitting, the sealant material being

formed to prevent the migration of flammable or explosive gases or liquids along the

electrical conduit to a potential ignition source, each sealant dam comprising a

cylindrical disk of resilient material having one or more wire orifices through the disk,

the orifices being aligned with the axis of the disk and the orifices being separated to

provide a desired clearance between the respective wires which are to passed through the

orifices, the diameter of each orifice providing for a tight fit between the inside surface of

the orifice and the outside surface of the respective wire passing through the orifice, and

the diameter of each disk providing for a tight fit between the disk and the inside surface

of the conduit seal-off fitting.

16. A pair of sealant dams as recited in Claim 15 wherein the resilient

material is polyethylene foam.

17. A pair of sealant dams as recited in Claim 16 wherein the polyethylene

foam has a density of approximately four pounds per cubic foot.

18. A pair of sealant dams as recited in Claim 15 wherein the wire orifices are

molded into each disk at the time that the disk is made.

19. A pair of sealant dams as recited in Claim 15 wherein the wire orifices are

punched into each disk.

20. A pair of sealant dams as recited in Claim 15 wherein the wire orifices are

formed by passing a heated probe through the disk at each position that a orifice is

desired.

21. Method for sealing electrical conduit with one or more wires therein to

prevent the migration of flammable or explosive gases or liquids through the electrical

conduit to a potential ignition source, the method comprising:

a) a step of passing each of the wires through a respective wire orifice in one

or more cylindrical dams of resilient material, each wire orifice of each

cylindrical dam being aligned with the axis of the cylindrical dam, the

wire orifices being separated by a desired clearance, and the orifices being

of a diameter to fit tightly on the wires;

b) a step of sliding each dam along the wires into a seal-off fitting until it is situated securely in a respective desired dam position, the diameter of

each dam being such to provide for the dam to press tightly upon the

interior surface of the seal-off fitting when it is positioned in the

respective desired dam position; and

c) a step of pouring time curing sealant material through an access port on

the seal-off fitting until the sealant material is of a desired thickness or

occupies a desired space in the seal-off fitting; and

d) allowing the sealant material to cure, thereby forming a seal against gas or

liquid migration through the conduit or around the wires.

22. A method as recited in Claim 21 wherein the resilient material is a

polyethylene foam.

23. Method as recited in Claim 22 wherein the polyethylene foam has a

density of approximately four pounds per cubic foot.

24. Method as recited in Claim 22 wherein the wire orifices are formed in the

dam by a molding process at the time that the dam is formed.

25. Method as recited in Claim 22 wherein the wire orifices are made by

punching the dam in the desired locations.

26. Method as recited in Claim 22 wherein the wire orifices are made by

passing a heated probe through the dam at the desired locations.

27. Method as recited in Claim 22 wherein the seal-off fitting is a vertical

seal-off fitting and one sealant dam is utilized.

28. Method as recited in Claim 22 wherein the seal-off fitting is a horizontal

seal-off fitting and two sealant dams are utilized.

29. Method for sealing electrical conduit with one or more wires therein to prevent the migration of flammable or explosive gases or liquids through the electrical conduit to a potential ignition source, the method comprising: a) a step of passing each of the wires through a respective wire orifice in a cylindrical dam of resilient material, each wire orifice being aligned with the axis of the cylindrical dam, the wire orifices being separated by a desired clearance, and the orifices being of a diameter to fit tightly on the wires; b) a step of sliding the dam along the wires into a vertical seal-off fitting

until it is situated securely in the desired dam position, the diameter of the dam being such to provide for the dam to press tightly upon the interior surface of the seal-off fitting when it is positioned in the desired dam position; and c) a step of pouring time curing sealant material through an access port on the seal-off fitting on top of the dam in a desired thickness; and d) allowing the sealant material to cure, thereby forming a seal against gas or liquid migration through the conduit or around the wires.

30. Method as recited in Claim 29 wherein the resilient material is a polyethylene foam.

31. Method as recited in Claim 30 wherein the polyethylene foam has a density of approximately four pounds per cubic foot.

32. Method as recited in Claim 29 wherein the wire orifices are formed in the

dam by a molding process at the time that the dam is formed.

33. Method as recited in Claim 29 wherein the wire orifices are made by

punching the dam in the desired locations.

34. Method as recited in Claim 29 wherein the wire orifices are made by

passing a heated probe through the dam at the desired locations.

35. Method for sealing electrical conduit with one or more wires therein to

conduit to a potential ignition source, the method comprising:

a) a step of passing each of the wires through a respective wire orifice in a

first cylindrical dam of resilient material, each wire orifice being aligned with the axis of the cylindrical dam, the wire orifices being separated by a

desired clearance, and the orifices being of a diameter to fit tightly on the

wires;

b) a step of sliding the first cylindrical dam along the wires into a horizontal

seal-off fitting until it is situated securely in a first installation position,

the diameter of the first cylindrical dam being such to provide for the first

cylindrical dam to press tightly upon the interior surface of the seal-off

fitting when it is positioned in the first installation position;

c) a step of passing each of the wires through a respective wire orifice in a second cylindrical dam of resilient material, each wire orifice being

aligned with the axis of the cylindrical dam, the wire orifices being

separated by a desired clearance, and the orifices being of a diameter to fit

tightly on the wires;

d) a step of sliding the second cylindrical dam along the wires into the horizontal seal-off fitting until it is situated securely in a second

installation position, the diameter of the second cylindrical dam being

such to provide for the second cylindrical dam to press tightly upon the

interior surface of the seal-off fitting when it is positioned in the second

installation position; e) a step of pouring time curing sealant material through an access port into

seal-off fitting space between the first cylindrical dam and the second

cylindrical dam; and

f) allowing the sealant material to cure, thereby forming a seal against gas or

liquid migration through the conduit or around the wires.

36. Method as recited in Claim 35 wherein the resilient material is a

polyethylene foam.

37. Method as recited in Claim 36 wherein the polyethylene foam has a

density of approximately four pounds per cubic foot.

38. Method as recited in Claim 35 wherein the wire orifices are formed in the first cylindrical dam and the second cylindrical dam by a molding process at the time that

the dams are formed.

39. Method as recited in Claim 35 wherein the wire orifices are made by

punching the first cylindrical dam and the second cylindrical dam in the desired

locations.

40. Method as recited in Claim 35 wherein the wire orifices are made by

passing a heated probe through the first cylindrical dam and the second cylindrical dam in the desired locations.