Abstract:
Sewer gas sampling and analyzing devices include a dish-shaped manhole insert having a manhole insert interior and a manhole insert exterior outside the manhole insert interior; a manhole insert vent valve carried by the manhole insert, the manhole insert vent valve having a valve inlet disposed in fluid communication with the manhole insert exterior and a valve outlet and the manhole insert vent valve facilitates substantially unrestricted flow of gas from the valve inlet to the valve outlet; and a gas detector unit disposed in fluid communication with the valve outlet of the manhole insert vent valve. Sewer gas sampling and analyzing methods are also disclosed.

Description:
FIELD 
     Illustrative embodiments of the disclosure generally relate to manholes for sewer systems and the like. More particularly, illustrative embodiments of the disclosure relate to sewer gas sampling and analyzing devices and methods which can be used to sample and analyze sewer conditions such as the composition and quantity of sewer gas emitted through a manhole insert in a manhole structure. 
     BACKGROUND 
     The background description provided herein is solely for the purpose of generally presenting the context of various illustrative embodiments of the disclosure. Aspects of the background description are neither expressly nor impliedly admitted as prior art against the claimed subject matter. 
     In sewer systems, manhole structures typically facilitate access to subterranean piping. A typical manhole structure may be fitted with a manhole cover assembly having a ring-shaped manhole frame which is secured in the above-ground extending portion of the manhole structure. A manhole cover which is seated on the manhole frame can be selectively removed therefrom to facilitate access to the interior of the manhole structure and the sewer system. 
     One of the problems which is frequently encountered with conventional manhole structures is that methane, hydrogen sulfide, carbon monoxide, sulfur dioxide and other gases have a tendency to accumulate in the sewer system beneath the manhole cover assembly. These gases may create hazardous conditions which may exist with lack of oxygen in some cases to potentially pose a hazard to personnel who must periodically enter the manhole for maintenance, repair, cleaning and/or other purposes. 
     Accordingly, sewer gas sampling and analyzing devices and methods which can be used to sample and analyze sewer conditions such as the composition and quantity of sewer gas emitted through a manhole insert in a manhole structure are needed. 
     SUMMARY 
     Illustrative embodiments of the disclosure are generally directed to sewer gas sampling and analyzing devices which can be used to sample and analyze sewer conditions such as the composition and quantity of sewer gas emitted through a manhole insert in a manhole structure. An illustrative embodiment of the sewer gas sampling and analyzing devices includes a dish-shaped manhole insert having a manhole insert interior and a manhole insert exterior outside the manhole insert interior; a manhole insert vent valve carried by the manhole insert, the manhole insert vent valve having a valve inlet disposed in fluid communication with the manhole insert exterior and a valve outlet and the manhole insert vent valve facilitates substantially unrestricted flow of gas from the valve inlet to the valve outlet; and a gas detector unit disposed in fluid communication with the valve outlet of the manhole insert vent valve. 
     Illustrative embodiments of the disclosure are further generally directed to sewer gas sampling and analyzing methods. An illustrative embodiment of the sewer gas sampling and analyzing methods includes installing a manhole insert vent valve of a sewer gas sampling and analyzing device in a manhole insert; installing the manhole insert in a manhole over a sewer system; placing a gas detector unit in fluid communication with the manhole insert vent valve; distributing sewer gas from the sewer system through the manhole insert vent valve to the gas detector unit; and obtaining at least one sewer condition reading indicating at least one sewer condition in the sewer system. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Illustrative embodiments of the disclosure will now be described, by way of example, with reference to the accompanying drawings, wherein: 
         FIG. 1  is a cross-sectional view of manhole insert, manhole insert vent valve and valve tubing components of an illustrative embodiment of the sewer gas sampling and analyzing devices; 
         FIG. 2  is a top view of the manhole insert, manhole insert vent valve and valve tubing components of the illustrative sewer gas sampling and analyzing device; 
         FIG. 3  is a cross-sectional view of the manhole insert, manhole insert vent valve and valve tubing components of the illustrative sewer gas sampling and analyzing device, installed in a manhole structure in typical application of the device; 
         FIG. 3A  is a side view of a manhole insert vent valve seated in a vent plug (illustrated in cross-section) which is inserted in a valve opening in the manhole insert (also in cross-section) of the illustrative sewer gas sampling and analyzing device; 
         FIG. 4  is an exploded side view, partially in section, of an illustrative sewer gas sampling and analyzing device; 
         FIG. 5  is a side view, partially in section, of the assembled illustrative sewer gas sampling and analyzing device; 
         FIG. 6  is a sectional view of a manhole structure with the manhole insert of the illustrative sewer gas sampling and analyzing device inserted in the manhole structure and a gas detector unit coupled to the manhole insert vent valve of the device to sample and analyze sewer gases from a sewer system beneath the manhole structure; 
         FIG. 7  is a functional block diagram which illustrates typical flow of sewer gas through the manhole insert vent valve, valve tubing and gas filter to the gas detector of an illustrative sewer gas sampling and analyzing device in typical application of the device; and 
         FIG. 8  is a flow diagram of an illustrative embodiment of the sewer gas sampling and analyzing methods. 
     
    
    
     DETAILED DESCRIPTION 
     The following detailed description is merely exemplary in nature and is not intended to limit the described embodiments or the application and uses of the described embodiments. As used herein, the word “exemplary” or “illustrative” means “serving as an example, instance, or illustration.” Any implementation described herein as “exemplary” or “illustrative” is not necessarily to be construed as preferred or advantageous over other implementations. All of the implementations described below are exemplary implementations provided to enable users skilled in the art to practice the disclosure and are not intended to limit the scope of the claims. Moreover, the illustrative embodiments described herein are not exhaustive and embodiments or implementations other than those which are described herein and which fall within the scope of the appended claims are possible. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary or the following detailed description. 
     Referring initially to  FIGS. 1-7  of the drawings, an illustrative embodiment of the sewer gas sampling and analyzing devices, hereinafter device, is generally indicated by reference numeral  1  in  FIGS. 4-7 . As illustrated in  FIGS. 1-3A , the device  1  may include a manhole insert  40 . As illustrated in  FIG. 3 , in typical application of the device  1 , which will be hereinafter described, the manhole insert  40  may be seated on an annular manhole shoulder  53  inside a manhole frame  55  of a manhole cover assembly  50  in a manhole structure  58 . The manhole frame  55  of the manhole cover assembly  50  may be deployed over a subterranean sewer system  56 . A manhole cover  51  may normally be supported on an annular manhole cover seat  54  on the manhole frame  55 . A manhole opening  52  may be defined between the manhole insert  40  and the manhole cover  51 . 
     As illustrated in  FIGS. 1 and 2 , in some embodiments, the manhole insert  40  may be pan-shaped with a flat manhole insert bottom  41  and an annular manhole insert side  42  extending outwardly at an angle from the manhole insert bottom  41 . The manhole insert bottom  41  and the manhole insert side  42  may define a manhole insert interior  43   a . An interior insert bottom surface  41   a  of the manhole insert bottom  41  may face the manhole insert interior  43   a . An exterior insert bottom surface  41   b  of the manhole insert bottom  41  may face a manhole insert exterior  43   b.    
     The manhole insert side  42  may have a manhole insert rim  47 . An annular insert flange  44  may extend outwardly from the manhole insert rim  47  of the manhole insert side  42 . Multiple insert stiffeners  45  may be provided in the insert bottom  41  for reinforcement purposes. A valve opening  46  ( FIG. 3A ) may extend through the manhole insert bottom  41  of the manhole insert  40  for purposes which will be hereinafter described. At least one lift handle  48  may be provided on the interior insert bottom surface  41   a  of the insert bottom  41  inside the manhole insert interior  43  for the purpose of lifting the manhole insert  40  from the manhole cover assembly  50  to access the underlying sewer system  56 . 
     As illustrated in  FIGS. 4 and 5 , a manhole insert vent valve  8  is seated in the valve opening  46  in the insert bottom  41  of the manhole insert  40  according to the knowledge of those skilled in the art. In some embodiments, a vent plug  2  may be inserted in the valve opening  46 . As illustrated in  FIG. 3A , the vent plug  2  may include a vent plug wall  3  and a valve seat  4  which extends through the vent plug wall  3 . The manhole insert vent valve  8  may be seated in the valve seat  4  of the vent plug  2 . In other embodiments, the manhole insert vent valve  8  may be seated in the valve opening  46  using alternative techniques or structures known by those skilled in the art. 
     The manhole insert vent valve  8  may include any type of valve which is suitable for venting sewer gas  57  from the sewer system  56  beneath the manhole cover assembly  50  and through the insert bottom  41  of the manhole insert  40 . In some embodiments, the manhole insert vent valve  8  may include an automotive vacuum valve known by those skilled in the art. For example and without limitation, in some embodiments, the manhole insert vent valve  8  may include a 3/16 inch VITON®/KYNAR® standard check valve (Item No. 64108) which is available from United States Plastic Corp. (www.usplastic.com). As illustrated in  FIG. 3A , the manhole insert vent valve  8  may include a valve housing  9  which contains the functional components of the manhole insert vent valve  8 . The valve housing  9  may have a valve inlet  9   a  and a valve outlet  9   b . In venting of the sewer gas  57  from the sewer system  56 , as further illustrated in  FIG. 3A , the manhole insert vent valve  8  may normally facilitate substantially unrestricted flow of sewer gas  57  from the valve inlet  9   a  through the valve housing  9  to the valve outlet  9   b . A valve inlet connector  10  may extend from the valve housing  9  in fluid communication with the valve inlet  9   a . A connector barb  11  may be provided on the valve inlet connector  10 . A valve outlet connector  12  may extend from the valve housing  9  in fluid communication with the valve outlet  9   b . A connector barb  11  may be provided on the valve outlet connector  12 . In some embodiments, a retainer washer  18  may be provided on the valve inlet connector  10  to retain the manhole insert vent valve  8  in a seated position in the valve seat  4  of the vent plug  2 . 
     As further illustrated in  FIGS. 4-7 , valve tubing  20  may be disposed in fluid communication with the valve outlet  9   b  of the valve housing  9  of the manhole insert vent valve  8 . The valve tubing  20  may have a tubing inlet end  20   a  which is coupled to the valve housing  9  of the manhole insert vent valve  8  at the valve outlet  9   b  and a tubing discharge end  20   b  which is opposite the tubing inlet end  20   a . The tubing inlet end  20   a  of the valve tubing  20  may receive the valve outlet connector  12  of the manhole insert vent valve  8 . As illustrated in  FIG. 1 , in some embodiments, the length of the valve tubing  20  may be selected such that the tubing discharge end  20   b  protrudes beyond the manhole insert rim  47  of the manhole insert  40  for purposes which will be hereinafter described. 
     As illustrated in  FIGS. 4 and 5 , a gas filter  24  may be disposed in fluid communication with the valve outlet  9   b  of the valve housing  9  of the manhole insert vent valve  8 . The gas filter  24  may filter moisture and/or particulate impurities from the sewer gas  57  as the sewer gas  57  flows through the gas filter  24 . In some embodiments, the gas filter  24  may be disposed in fluid communication with the tubing discharge end  20   b  of the valve tubing  20 , as illustrated. In some embodiments, a filter inlet connector  25  may extend from a first end of the gas filter  24  for insertion into the tubing discharge end  20   b  of the valve tubing  20 . A filter outlet connector  27  may extend from a second end of the gas filter  24 . In other embodiments, the gas filter  24  may be omitted from the device  1 . 
     A gas detector unit  30  may be disposed in fluid communication with the valve outlet  9   b  of the valve housing  9  of the manhole insert valve  8 . In some embodiments, the gas detector unit  30  may be disposed in fluid communication with the gas filter  24  and may be selectively coupled to the filter outlet connector  27 , as illustrated. The gas detector unit  30  may include any type of commercially-available electronic gas detector unit which is capable of detecting and monitoring or analyzing the oxygen content and the presence and quantities of toxic or flammable gases such as methane, hydrogen sulfide, carbon monoxide, sulfur dioxide and/or other potentially hazardous gases. In some embodiments, the gas detector unit  30  may include a hand-held gas detector unit console  31 . A display  32  may be provided on the gas detector unit console  31 . Controls  33  on the gas detector unit console  31  may facilitate selection from among multiple display parameters which appear on the display  32 . A speaker  34  may be provided on the gas detector unit console  31  to provide an audible indication of potentially hazardous gases detected using the gas detector unit  30 . An elongated detector tube  35  may extend from the gas detector unit console  31 . In some embodiments, a tube connector  36  may terminate the detector tube  35 . The tube connector  36  may be adapted for connection to the filter outlet connector  27  on the gas filter  24 . A non-limiting example of a gas detector unit  30  which is suitable for implementation of the device  1  is the Tetra Multi-Gas Monitor which is available from Crowcon Detection Instruments Ltd. (www.crowcon.com). In some embodiments, the gas filter  24  may be a component part of the gas detector unit  30 . A gas pump (not illustrated) may be incorporated into the gas detector unit  30  according to the knowledge of those skilled in the art in some embodiments. Accordingly, in typical application of the device  1 , which will be hereinafter described, the gas pump (not illustrated) in the gas detector unit  30  may be operable to pump the sewer gas  57  from the sewer system  56  through the manhole insert vent valve  8  and the valve tubing  20 , through the gas filter  24  to the gas detector unit  30 . The gas filter  24  may remove moisture and/or particulate impurities from the sewer gas  57 . In some applications, the sewer gas  57  may flow from the sewer system  56  to the gas detector unit  30  of the device  1  under natural pressure and without operation of a gas pump. The gas detector unit  30  analyzes the sampled sewer gas  57  and indicates at least one sewer condition such as the quantities and compositions of gases in the sewer gas  57  and the quantity of oxygen in the sewer system  56 . This discretionary information may enable personnel to take precautionary measures in removing the manhole insert  40  from the manhole cover assembly  50  preparatory to entering the sewer system  56  through the manhole structure  58 . 
     As illustrated in  FIGS. 3, 3A, 6 and 7 , typical application of the device  1  may be as follows. The manhole insert  40 , with the vent plug  2 , the manhole insert vent valve  8  and the valve tubing  20  installed therein, is seated in the manhole  50  over the sewer system  56  typically by initially removing the manhole cover  51  from the annular manhole over seat  54  on the manhole frame  55 , seating the manhole insert flange  44  of the manhole insert  40  onto the annular manhole shoulder  53  in the manhole frame  55  and replacing the manhole cover  51  on the manhole cover seat  54 . Accordingly, the manhole insert interior  43   a  of the manhole insert  40  communicates with the manhole opening  52  beneath the manhole cover  51 , whereas the manhole insert exterior  43   b  of the manhole insert  40  communicates with the underlying sewer system  56 . The valve inlet connector  10  on the valve housing  9  of the manhole insert vent valve  8  is disposed in fluid communication with the manhole insert exterior  43   b  of the manhole insert  40 . The manhole insert vent valve  8  normally facilitates substantially unrestricted unidirectional flow of sewer gas  57  from the sewer system  56  through the valve vent connector  10 , the valve housing  9  and the valve outlet connector  12 , respectively, of the manhole insert vent valve  8 , and the valve tubing  20 . The sewer gas  57  may be discharged from the tubing discharge end  20   b  of the valve tubing  20  and accumulate in the manhole opening  52  beneath the manhole cover  51 , or alternatively, may be vented from the manhole opening  52  through one or more manhole cover openings (not illustrated) in the manhole cover  51 . 
     When repair, maintenance and/or cleaning of the sewer system  56  beneath the manhole structure  58  is required, the manhole cover  51  may be removed from the manhole cover seat  54 , exposing the upward-standing valve tubing  20  of the device  1 . As illustrated in  FIGS. 4 and 5 , the detector tube  35  of the gas detector unit  30  may be connected to the gas filter  24 , and the gas filter  24  may be connected to the valve tubing  20 . In some embodiments, the gas pump (not illustrated) may be operated to pump the sewer gas  57  from the sewer system  56  and through the valve inlet connector  10 , the valve housing  9  and the valve outlet connector  12 , respectively, of the manhole insert vent valve  8  and then through the valve tubing  20  and the detector tube  35  to the gas detector unit  30 . In some applications, the sewer gas  57  may flow from the sewer system  56  to the gas detector unit  30  of the device  1  under natural pressure and without operation of the gas pump. The gas filter  24  may remove moisture and/or particulate impurities from the sewer gas  57 . Accordingly, the gas detector unit  30  may detect and analyze the sewer gas  57  and, based on analysis of the sewer gas  57 , display one or more sewer condition readings which indicate sewer conditions that may potentially adversely affect personnel who take part in the repair, maintenance and/or cleaning operation in the sewer system  56 . These sewer condition readings may include such parameters as the noxious gaseous constituents of the sewer gas  57  as well as the concentrations of the constituents and quantification of oxygen in the sewer gas  57 . These parameters are known by or can be readily determined by personnel who are routinely employed in the repair, maintenance and/or cleaning of sewer systems  56 . 
     After the sewer condition readings are taken, the gas filter  24  may be disconnected from the valve tubing  20 . In the event that the sewer condition readings indicated by the gas detector unit  30  reveal that concentrations of the gaseous constituents in the sewer gas  57  are above a predetermined minimum concentration threshold level for the constituents and/or the oxygen content of the sewer gas  57  falls below a predetermined minimum oxygen content threshold level, the personnel may take precautionary measures upon subsequently removing the manhole insert  40  from the manhole structure  58  to prevent the noxious constituents and/or lack of oxygen in the sewer gas  57  from rendering any of the personnel unconscious. These precautions may prevent the personnel from subsequently inadvertently falling into the sewer system  56 . Corrective measures such as the installation of blowers (not illustrated) in the sewer system  56  may subsequently be undertaken to more effectively introduce fresh air into the sewer system  56 . After the repair, maintenance and/or cleaning operation is completed, the manhole insert  40  may be replaced on the manhole shoulder  53  and the manhole cover  51  replaced on the manhole cover seat  54  with the vent plug  2 , the manhole insert vent valve  8  and the valve tubing  20  remaining in place in the manhole insert  40 . 
     As illustrated in  FIG. 3 , it will be appreciated by those skilled in the art that in some embodiments of the sewer gas sampling and analyzing device  1 , the length of the valve tubing  20  may be selected such that the tubing discharge end  20   b  of the valve tubing  20  protrudes beyond the manhole insert rim  47  of the manhole insert  40 . Accordingly, the valve tubing  20  prevents rainwater or other precipitation which may accumulate in the manhole insert interior  43   a  of the manhole insert  40  from entering the manhole insert vent valve  8  through the valve outlet  9   b.    
     Referring next to  FIG. 8  of the drawings, a sewer gas sampling and analyzing method  100  is illustrated. At block  102 , a manhole insert vent valve of a sewer gas sampling and analyzing device is installed in a manhole insert. At block  104 , the manhole insert is installed in a manhole cover assembly of a manhole structure over a sewer system. At block  106 , a manhole cover is placed on the manhole cover assembly. At block  108 , a gas filter may be connected to a gas detector unit of the sewer gas sampling and analyzing device. At block  110 , the manhole cover is removed from the manhole cover assembly. At block  112 , the gas filter is connected to valve tubing on the manhole insert vent valve. At block  114 , sewer gas may be pumped from the sewer system through the manhole cover assembly, the manhole insert vent valve and the valve tubing to the gas detector unit. In other embodiments, the sewer gas may flow from the sewer system through the manhole cover assembly, the manhole insert vent valve and the valve tubing to the gas detector unit under natural pressure and without operation of a gas pump. 
     At block  116 , at least one sewer condition reading is obtained. The sewer condition reading may include such parameters as the noxious gaseous constituents of the sewer gas as well as the concentrations of the constituents and quantification of oxygen in the sewer gas. At block  118 , the manhole insert may be carefully removed from the manhole cover assembly to prevent personnel from being rendered unconscious and inadvertently falling into the sewer system if the sewer condition reading on the gas detector unit reveals concentrations of the gaseous constituents in the sewer gas that are above a predetermined minimum concentration threshold level for the constituents and/or an oxygen content which falls below a predetermined minimum oxygen content threshold level. 
     While illustrative embodiments of the disclosure have been described above, it will be recognized and understood that various modifications can be made and the appended claims are intended to cover all such modifications which may fall within the spirit and scope of the disclosure.