Method of and system for venting out buildup of explosive gases in a manhole

• US 6,551,015 B1
• Filed: 02/25/2002
• Issued: 04/22/2003
• Est. Priority Date: 07/25/2000
• Status: Expired due to Fees

• Current Assignee: Department of Water and Power
• Original Assignee: Department of Water and Power
• Inventors: Poosti, Saʼid S., Khajavi, Mohammed B.
• Primary Examiner(s): Swann, J. J.
• Application Number:
  US10/084,212
• Time in Patent Office: 421 Days
• Field of Search: 404/25, 137/43, 49/21, 52/20
• US Class Current: 404/25
• CPC Class Codes: E02D 29/1436 with overflow or explosion control means, e.g. check or relief valves

Abstract

A method of and system used for venting out buildup of explosive gases in a manhole caused by an explosion and including a support frame, a two inch thick plate member positioned on top of the support frame, a plurality of restraining assemblies and a manhole cover for covering the manhole. The support frame and the plate member are embedded into a street and positioned above the manhole, where openings are aligned with the manhole. Three retaining assemblies are positioned on opposite sides of the manhole cover. Each retaining assembly includes a rod, a stop plate, a coil spring, a support plate and a nut. The rod extends downwardly through the dirt and the horizontal concrete base ledge, where the stop plate, the coil spring, the support plate and the nut are positioned and secured to the other end of the rod.

Claims

1. A method of venting out explosive gases in a manhole which connects directly to an underground conduit system, the method comprising the steps of:

a. installing a generally rectangular shaped main support frame below pavement of a street and having a central opening, an annular flange collar surrounding the central opening and extending downwardly therefrom, and three pairs of spaced apart mounting apertures extending therethrough and located on each opposite side of the central opening;

b. positioning said main support frame over said manhole such that said central opening is aligned with said manhole;

c. providing a generally rectangular shaped plate member having a central opening, and three pairs of spaced apart mounting apertures extending therethrough and located on each opposite side of the central opening;

d. positioning said plate member on top of said support frame such that said central opening of said plate member and said three pairs of mounting apertures of said plate member are respectively aligned with said central opening of said support frame and said three pairs of mounting apertures of said support frame;

e. welding an annular angle flange to said plate member and surrounding said central opening;

f. seating and securing a manhole cover to said annular angle flange and sized to cover said central openings of said support frame and said plate member leading to said manhole;

g. providing a plurality of restraining assemblies, each having an elongated rod, an upper slidable stop plate, a coil spring, a lower fixed support plate and a nut;

h. respectively inserting a shaft portion of said elongated rod of said each restraining assembly through said each aperture of said plate member and said support frame such that a head portion of said elongated rod of said each restraining assembly abuts against an upper surface of said plate member and said shaft portion extends through a horizontal concrete base ledge of said manhole;

i. threadedly engaging said nut of said each restraining assembly respectively to said elongated rod;

j. positioning said lower fixed support plate of said each restraining assembly around said elongated rod and securing to said nut;

k. surrounding a lowermost part of said rod with said coil spring of said each restraining assembly;

l. welding said upper slidable stop plate of said each restraining assembly on top of said coil spring and around said elongated rod; and

m. allowing said rod of said each restraining assembly to move smoothly up and down without any friction;

n. whereby when an explosion occurs in said manhole, the pressure caused by the explosion lifts said plate member away from said support frame which in turn moves said rod of said each restraining assembly upwardly such that said upper slidable stop plate of said each restraining assembly strikes against the bottom of said horizontal concrete base ledge, where said coil spring of said each restraining assembly is compressed such that said plate member is lifted upwardly to a limited predetermined distance to form a gap between said plate member and said support frame to allow the explosive gases to escape from said manhole, and after all of the explosive gases have escaped, said coil spring of said each restraining assembly is uncompressed forcing down said plate member to said support frame back into alignment with said manhole.

2. The method in accordance with claim 1, wherein said coil spring means is a heavy duty compression spring.

3. The method in accordance with claim 1, further comprising the step of providing a thickness of at least two inches to said plate member.

4. A method of venting out explosive gases in a manhole which connects directly to an underground conduit system, the method comprising the steps of:

a. installing a plate member below pavement of a street and having an opening and at least three pairs of spaced apart mounting apertures extending therethrough and located on opposite sides of the opening;

b. positioning said plate member above said manhole such that said opening is aligned with said manhole;

c. attaching an angle flange to said plate member and surrounding said opening;

d. seating and securing a manhole cover to said angle flange and sized to cover said opening of said plate member leading to said manhole;

e. providing a plurality of restraining assemblies, each having an elongated rod, an upper slidable stop plate, spring means, a lower fixed support plate and a nut;

f. respectively inserting a shaft portion of said elongated rod of said each restraining assembly through said each aperture of said plate member such that a head portion of said elongated rod of said each restraining assembly abuts against an upper surface of said plate member and the shaft portion extending through a base ledge of said manhole;

g. threadedly engaging said nut of said each restraining assembly respectively with said elongated rod;

h. positioning said lower fixed support plate of said each restraining assembly around said elongated rod and securing to said nut;

i. surrounding a lowermost part of said rod with said spring means of said each restraining assembly; and

j. attaching said upper slidable stop plate of said each restraining assembly on top of said spring means and around said elongated rod;

k. whereby when an explosion occurs in said manhole, the pressure caused by the explosion lifts said plate member from a seated position which in turn moves said rod of said each restraining assembly upwardly such that said upper slidable stop plate of said each restraining assembly strikes against the bottom of said base ledge, where said spring means of said each restraining assembly is compressed such that said plate member is lifted upwardly to a limited predetermined distance to form a gap between the pavement and said plate member to allow the explosive gases to escape from said manhole, and after all of the explosive gases have escaped, said spring means of said each restraining assembly is uncompressed forcing down said plate member back into alignment with said manhole.

5. The method accordance with claim 4, further comprising the steps of installing a generally rectangular shaped main support frame having an opening, a flange collar surrounding the opening and extending downwardly therefrom, and at least three pairs of spaced apart mounting apertures extending therethrough and located on opposite sides of the opening, the main support frame being between said manhole and said plate member such that said opening is aligned with said manhole and said opening of said plate member.

6. The method in accordance with claim 4, wherein said spring means is a heavy duty compression spring.

7. The method in accordance with claim 4, further comprising the step of providing a thickness of at least two inches to said plate member.

8. The method in accordance with claim 4, further comprising the step of installing a PVC pipe to said rod of said each restraining assembly to allow said rod to move smoothly up and down without any friction.

9. A method of venting out explosive gases in a manhole which connects to an underground conduit system, the method comprising the steps of:

a. installing a plate member having an opening, and at least one pair of mounting apertures extending therethrough and located on opposite sides of the opening;

b. positioning said plate member above said manhole such that said opening is aligned with said manhole;

c. removably covering said opening of said plate member leading to said manhole with a manhole cover

d. providing at least two restraining assemblies, each having a rod, an upper plate, a spring means, a lower plate and a nut;

e. respectively inserting a shaft portion of said rod of said each restraining assembly through said each aperture of said plate member such that a head portion of said rod of said each restraining assembly abuts against an upper surface of said plate member and the shaft portion extends through a base ledge of said manhole;

f. respectively attaching said nut of said each restraining assembly to said shaft portion of said rod;

g. positioning said lower plate of said each restraining assembly around said rod and securing to said nut;

h. surrounding said shaft portion of said rod with said spring means of said each restraining assembly; and

i. attaching said upper plate of said each restraining assembly on top of said spring means and around said shaft portion of said rod;

whereby when an explosion occurs in said manhole, the pressure caused by the explosion lifts said plate member from a seated position which in turn moves said rod of said each restraining assembly upwardly such that said upper plate of said each restraining assembly strikes against the bottom of said base ledge, where said spring means of said each restraining assembly is compressed such that said plate member is lifted upwardly to a limited predetermined distance to form a gap between the pavement and said plate member to allow the explosive gases to escape from said manhole, and after all of the explosive gases have escaped, said spring means of said each restraining assembly is uncompressed forcing down said plate member back into alignment with said manhole.

10. The method in accordance with claim 9, further comprising the step of installing a main support frame having an opening, a flange collar surrounding the opening and extending downwardly therefrom, and at least one pair of spaced apart mounting apertures extending therethrough and located on opposite sides of the opening, the main support frame being between said manhole and said plate member such that said opening is aligned with said manhole and said opening of said plate member.

11. The method in accordance with claim 9, further comprising the step of attaching an angle flange to said plate member and surrounding said opening for accommodating said manhole cover.

12. The method in accordance with claim 9, wherein said spring means is a heavy duty coil compression spring.

13. The system in accordance with claim 9, wherein the thickness of said plate member is approximately two inches.

14. The method in accordance with claim 9, further comprising the step of providing a thickness of at least two inches to said plate member.

15. The method in accordance with claim 9, further comprising the step of installing a PVC pipe to said rod of said each restraining assembly to allow said rod to move smoothly up and down without any friction.

16. A method of venting out explosive gases in a manhole which connects to an underground conduit system, the method comprising the steps of:

a. installing a plate member having an opening, and at least one pair of mounting apertures extending therethrough and located on opposite sides of the opening;

b. positioning said plate member above said manhole such that said opening is aligned with said manhole;

c. removably covering said opening of said plate member leading to said manhole with a manhole cover;

d. respectively inserting a shaft portion of a rod of each restraining assembly through said each mounting aperture of said plate member such that a head portion of the rod of the each restraining assembly abuts against an upper surface of said plate member and the shaft portion extends through a base ledge of said manhole;

e. respectively attaching a nut of said each restraining assembly to said shaft portion of said rod of said each restraining assembly;

f. attaching a lower plate of said each restraining assembly to said rod and said nut;

g. surrounding said shaft portion of said rod of said each restraining assembly with a spring means; and

h. attaching an upper plate on top of said spring means and around said shaft portion of said rod of said each restraining assembly;

i. whereby when an explosion occurs in said manhole, the pressure caused by the explosion lifts said plate member from a seated position which in turn moves said rod of said each restraining assembly upwardly such that said upper plate of said each restraining assembly strikes against the bottom of said base ledge, where said spring means of said each restraining assembly is compressed such that said plate member is lifted upwardly to a limited predetermined distance to form a gap between the pavement and said plate member to allow the explosive gases to escape from said manhole, and after all of the explosive gases have escaped, said spring means of said each restraining assembly is uncompressed forcing down said plate member back into alignment with said manhole.

17. The method in accordance with claim 16, further comprising the step of installing a main support frame having an opening, a flange collar surrounding the opening and extending downwardly therefrom, and at least one pair of spaced apart mounting apertures extending therethrough and located on opposite sides of the opening, the main support frame being between said manhole and said plate member such that said opening is aligned with said manhole and said opening of said plate member.

18. The method in accordance with claim 16, further comprising the step of attaching an angle flange to said plate member and surrounding said opening for accommodating said manhole cover.

19. The method in accordance with claim 16, wherein said spring means is a heavy duty coil compression spring.

20. The method in accordance with claim 16, further comprising the step of providing a thickness of at least two inches to said plate member.

21. The method in accordance with claim 16, further comprising the step of installing a PVC pipe to said rod of said each restraining assembly to allow said rod to move smoothly up and down without any friction.