Patent Publication Number: US-9851276-B1

Title: Packing leak detection system

Description:
This application is a divisional and continuing application of, and claims priority to, U.S. Non-provisional application Ser. No. 13/204,659 (Miguez et al.), filed Aug. 6, 2011, which is incorporated herein by reference as if set forth in full below. 
    
    
     BACKGROUND OF THE INVENTION 
     I. Field 
     The present invention relates to a system for monitoring and annunciating leakage of gas vapors and/or volatile material from a volatile material compressor. 
     II. Background 
     A volatile material (gas) compressor is a pressure vessel in which a piston, moved by a compressor piston rod, compresses a volume of volatile material by decreasing the space in which the volatile material is contained. As the pressure increases, the higher pressure volatile material attempts to escape along the surface of the compressor piston rod and out of the compressor cylinder through the opening for the compressor piston rod. Packing material, which may take the form of a series of special rings, contained in a packing case, surrounds the compressor piston rod and impedes the volatile material from escaping into the environment. 
     When the packing material comprises rings, the efficiency of the rings is determined by several factors which include the conditions of the compressor piston, the compressor piston rod, the packing case and the rings, themselves. Wear of the packing rings is expected, and the timing of their replacement is crucial to efficient operation of the compressor apparatus and other compressor equipment. 
     We observe that regulatory requirements in the area of pollution prevention are becoming more and more stringent. Depending on the particular volatile material being compressed, for example, a volatile material (VOC) which may be regulated by the Environmental Protection Agency (EPA), leaks of escaping VOCs from a compressor apparatus can represent significant loss of revenue and could trigger possible environmental fines for the compressor operator. 
     Similarly, national emission standards for hazardous air pollutants (NESHAP) established pursuant to Section 112 of the Clean Air Act (as amended Nov. 15, 1990) regulate specific categories of stationary sources that emit (or have the potential to emit) one or more hazardous air pollutants (HAPs) (see generally Title 40 of the Code of Federal Regulations). Some examples of HAPs include formaldehyde, benzene, 1,3-butadiene, acrolein, acetaldehyde, and toluene (see larger illustrative list in Table 1). Similarly, a set of pollutants commonly referred to as “Criteria Pollutants” face regulatory scrutiny. These pollutants are generated by combustion and include Nitrous Oxides (NOx), Carbon Monoxide (CO) and Volatile Organic Compounds (VOCs). These compounds are regulated by the New Source Performance Standards (NSPS). A third set of regulated (or potentially soon-to-be regulated) gases are greenhouse gases (GHG), for example, methane and carbon dioxide. 
     
       
         
           
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                 Illustrative List of Hazardous Air Pollutants. 
               
            
           
           
               
               
            
               
                 CAS 
                 Chemical 
               
               
                 Number 
                 Name 
               
               
                   
               
            
           
           
               
               
            
               
                 75070 
                 Acetaldehyde 
               
               
                 60355 
                 Acetamide 
               
               
                 75058 
                 Acetonitrile 
               
               
                 98862 
                 Acetophenone 
               
               
                 53963 
                 2-Acetylaminofluorene 
               
               
                 107028 
                 Acrolein 
               
               
                 79061 
                 Acrylamide 
               
               
                 79107 
                 Acrylic acid 
               
               
                 107131 
                 Acrylonitrile 
               
               
                 107051 
                 Allyl chloride 
               
               
                 92671 
                 4-Aminobiphenyl 
               
               
                 62533 
                 Aniline 
               
               
                 90040 
                 o-Anisidine 
               
               
                 1332214 
                 Asbestos 
               
               
                 71432 
                 Benzene (including benzene from gasoline) 
               
               
                 92875 
                 Benzidine 
               
               
                 98077 
                 Benzotrichloride 
               
               
                 100447 
                 Benzyl chloride 
               
               
                 92524 
                 Biphenyl 
               
               
                 117817 
                 Bis(2-ethylhexyl)phthalate (DEHP) 
               
               
                 542881 
                 Bis(chloromethyl)ether 
               
               
                 75252 
                 Bromoform 
               
               
                 106990 
                 1,3-Butadiene 
               
               
                 156627 
                 Calcium cyanamide 
               
               
                 105602 
                 Caprolactam 
               
               
                 133062 
                 Captan 
               
               
                 63252 
                 Carbaryl 
               
               
                 75150 
                 Carbon disulfide 
               
               
                 56235 
                 Carbon tetrachloride 
               
               
                 463581 
                 Carbonyl sulfide 
               
               
                 120809 
                 Catechol 
               
               
                 133904 
                 Chloramben 
               
               
                 57749 
                 Chlordane 
               
               
                 7782505 
                 Chlorine 
               
               
                 79118 
                 Chloroacetic acid 
               
               
                 532274 
                 2-Chloroacetophenone 
               
               
                 108907 
                 Chlorobenzene 
               
               
                 510156 
                 Chlorobenzilate 
               
               
                 67663 
                 Chloroform 
               
               
                 107302 
                 Chloromethyl methyl ether 
               
               
                 126998 
                 Chloroprene 
               
               
                 1319773 
                 Cresols/Cresylic acid (isomers and mixture) 
               
               
                 95487 
                 o-Cresol 
               
               
                 108394 
                 m-Cresol 
               
               
                 106445 
                 p-Cresol 
               
               
                 98828 
                 Cumene 
               
               
                 94757 
                 2,4-D, salts and esters 
               
               
                 3547044 
                 DDE 
               
               
                 334883 
                 Diazomethane 
               
               
                 132649 
                 Dibenzofurans 
               
               
                 96128 
                 1,2-Dibromo-3-chloropropane 
               
               
                 84742 
                 Dibutylphthalate 
               
               
                 106467 
                 1,4-Dichlorobenzene(p) 
               
               
                 91941 
                 3,3-Dichlorobenzidene 
               
               
                 111444 
                 Dichloroethyl ether (Bis(2-chloroethyl)ether) 
               
               
                 542756 
                 1,3-Dichloropropene 
               
               
                 62737 
                 Dichlorvos 
               
               
                 111422 
                 Diethanolamine 
               
               
                 121697 
                 N,N-Dimethylaniline 
               
               
                 64675 
                 Diethyl sulfate 
               
               
                 119904 
                 3,3-Dimethoxybenzidine 
               
               
                 60117 
                 Dimethyl aminoazobenzene 
               
               
                 119937 
                 3,3′-Dimethyl benzidine 
               
               
                 79447 
                 Dimethyl carbamoyl chloride 
               
               
                 68122 
                 Dimethyl formamide 
               
               
                 57147 
                 1,1-Dimethyl hydrazine 
               
               
                 131113 
                 Dimethyl phthalate 
               
               
                 77781 
                 Dimethyl sulfate 
               
               
                 534521 
                 4,6-Dinitro-o-cresol, and salts 
               
               
                 51285 
                 2,4-Dinitrophenol 
               
               
                 121142 
                 2,4-Dinitrotoluene 
               
               
                 123911 
                 1,4-Dioxane (1,4-Diethyleneoxide) 
               
               
                 122667 
                 1,2-Diphenylhydrazine 
               
               
                 106898 
                 Epichlorohydrin (1-Chloro-2,3-epoxypropane) 
               
               
                 106887 
                 1,2-Epoxybutane 
               
               
                 140885 
                 Ethyl acrylate 
               
               
                 100414 
                 Ethyl benzene 
               
               
                 51796 
                 Ethyl carbamate (Urethane) 
               
               
                 75003 
                 Ethyl chloride (Chloroethane) 
               
               
                 106934 
                 Ethylene dibromide (Dibromoethane) 
               
               
                 107062 
                 Ethylene dichloride (1,2-Dichloroethane) 
               
               
                 107211 
                 Ethylene glycol 
               
               
                 151564 
                 Ethylene imine (Aziridine) 
               
               
                 75218 
                 Ethylene oxide 
               
               
                 96457 
                 Ethylene thiourea 
               
               
                 75343 
                 Ethylidene dichloride (1,1-Dichloroethane) 
               
               
                 50000 
                 Formaldehyde 
               
               
                 76448 
                 Heptachlor 
               
               
                 118741 
                 Hexachlorobenzene 
               
               
                 87683 
                 Hexachlorobutadiene 
               
               
                 77474 
                 Hexachlorocyclopentadiene 
               
               
                 67721 
                 Hexachloroethane 
               
               
                 822060 
                 Hexamethylene-1,6-diisocyanate 
               
               
                 680319 
                 Hexamethylphosphoramide 
               
               
                 110543 
                 Hexane 
               
               
                 302012 
                 Hydrazine 
               
               
                 7647010 
                 Hydrochloric acid 
               
               
                 7664393 
                 Hydrogen fluoride (Hydrofluoric acid) 
               
               
                 7783064 
                 Hydrogen sulfide 
               
               
                 123319 
                 Hydroquinone 
               
               
                 78591 
                 Isophorone 
               
               
                 58899 
                 Lindane (all isomers) 
               
               
                 108316 
                 Maleic anhydride 
               
               
                 67561 
                 Methanol 
               
               
                 72435 
                 Methoxychlor 
               
               
                 74839 
                 Methyl bromide (Bromomethane) 
               
               
                 74873 
                 Methyl chloride (Chloromethane) 
               
               
                 71556 
                 Methyl chloroform (1,1,1-Trichloroethane) 
               
               
                 78933 
                 Methyl ethyl ketone (2-Butanone) 
               
               
                 60344 
                 Methyl hydrazine 
               
               
                 74884 
                 Methyl iodide (Iodomethane) 
               
               
                 108101 
                 Methyl isobutyl ketone (Hexone) 
               
               
                 624839 
                 Methyl isocyanate 
               
               
                 80626 
                 Methyl methacrylate 
               
               
                 1634044 
                 Methyl tert butyl ether 
               
               
                 101144 
                 4,4-Methylene bis(2-chloroaniline) 
               
               
                 75092 
                 Methylene chloride (Dichloromethane) 
               
               
                 101688 
                 Methylene diphenyl diisocyanate (MDI) 
               
               
                 101779 
                 4,4′-Methylenedianiline 
               
               
                 91203 
                 Naphthalene 
               
               
                 98953 
                 Nitrobenzene 
               
               
                 92933 
                 4-Nitrobiphenyl 
               
               
                 100027 
                 4-Nitrophenol 
               
               
                 79469 
                 2-Nitropropane 
               
               
                 684935 
                 N-Nitroso-N-methylurea 
               
               
                 62759 
                 N-Nitrosodimethylamine 
               
               
                 59892 
                 N-Nitrosomorpholine 
               
               
                 56382 
                 Parathion 
               
               
                 82688 
                 Pentachloronitrobenzene (Quintobenzene) 
               
               
                 87865 
                 Pentachlorophenol 
               
               
                 108952 
                 Phenol 
               
               
                 106503 
                 p-Phenylenediamine 
               
               
                 75445 
                 Phosgene 
               
               
                 7803512 
                 Phosphine 
               
               
                 7723140 
                 Phosphorus 
               
               
                 85449 
                 Phthalic anhydride 
               
               
                 1336363 
                 Polychlorinated biphenyls (Aroclors) 
               
               
                 1120714 
                 1,3-Propane sultone 
               
               
                 57578 
                 beta-Propiolactone 
               
               
                 123386 
                 Propionaldehyde 
               
               
                 114261 
                 Propoxur (Baygon) 
               
               
                 78875 
                 Propylene dichloride (1,2-Dichloropropane) 
               
               
                 75569 
                 Propylene oxide 
               
               
                 75558 
                 1,2-Propylenimine (2-Methyl aziridine) 
               
               
                 91225 
                 Quinoline 
               
               
                 106514 
                 Quinone 
               
               
                 100425 
                 Styrene 
               
               
                 96093 
                 Styrene oxide 
               
               
                 1746016 
                 2,3,7,8-Tetrachlorodibenzo-p-dioxin 
               
               
                 79345 
                 1,1,2,2-Tetrachloroethane 
               
               
                 127184 
                 Tetrachloroethylene (Perchloroethylene) 
               
               
                 7550450 
                 Titanium tetrachloride 
               
               
                 108883 
                 Toluene 
               
               
                 95807 
                 2,4-Toluene diamine 
               
               
                 584849 
                 2,4-Toluene diisocyanate 
               
               
                 95534 
                 o-Toluidine 
               
               
                 8001352 
                 Toxaphene (chlorinated camphene) 
               
               
                 120821 
                 1,2,4-Trichlorobenzene 
               
               
                 79005 
                 1,1,2-Trichloroethane 
               
               
                 79016 
                 Trichloroethylene 
               
               
                 95954 
                 2,4,5-Trichlorophenol 
               
               
                 88062 
                 2,4,6-Trichlorophenol 
               
               
                 121448 
                 Triethylamine 
               
               
                 1582098 
                 Trifluralin 
               
               
                 540841 
                 2,2,4-Trimethylpentane 
               
               
                 108054 
                 Vinyl acetate 
               
               
                 593602 
                 Vinyl bromide 
               
               
                 75014 
                 Vinyl chloride 
               
               
                 75354 
                 Vinylidene chloride (1,1-Dichloroethylene) 
               
               
                 1330207 
                 Xylenes (isomers and mixture) 
               
               
                 95476 
                 o-Xylenes 
               
               
                 108383 
                 m-Xylenes 
               
               
                 106423 
                 p-Xylenes 
               
               
                 0 
                 Antimony Compounds 
               
               
                 0 
                 Arsenic Compounds (inorganic including arsine) 
               
               
                 0 
                 Beryllium Compounds 
               
               
                 0 
                 Cadmium Compounds 
               
               
                 0 
                 Chromium Compounds 
               
               
                 0 
                 Cobalt Compounds 
               
               
                 0 
                 Coke Oven Emissions 
               
               
                 0 
                 Cyanide Compounds 1   
               
               
                 0 
                 Glycol ethers 2   
               
               
                 0 
                 Lead Compounds 
               
               
                 0 
                 Manganese Compounds 
               
               
                 0 
                 Mercury Compounds 
               
               
                 0 
                 Fine mineral fibers 3   
               
               
                 0 
                 Nickel Compounds 
               
               
                 0 
                 Polycylic Organic Matter 4   
               
               
                 0 
                 Radionuclides (including radon) 5   
               
               
                 0 
                 Selenium Compounds 
               
               
                   
               
               
                 NOTE: For all listings above which contain the word “compounds” and for glycol ethers, the following applies: Unless otherwise specified, these listings are defined as including any unique chemical substance that contains the named chemical (i.e., antimony, arsenic, etc.) as part of that chemical&#39;s infrastructure. 
               
               
                   1 X′CN where X = H′ or any other group where a formal dissociation may occur. For example KCN or Ca(CN)2 
               
               
                   2 Includes mono- and di- ethers of ethylene glycol, diethylene glycol, and triethylene glycol R—(OCH2CH2) n —OR′ where: 
               
               
                   n  = 1, 2, or 3 
               
               
                 R = alkyl or aryl groups 
               
               
                 R′ = R, H, or groups which, when removed, yield glycol ethers with the structure: R—(OCH2CH) n —OH. Polymers are excluded from the glycol category. 
               
               
                   3 Includes mineral fiber emissions from facilities manufacturing or processing glass, rock, or slag fibers (or other mineral derived fibers) of average diameter 1 micrometer or less. 
               
               
                   4 Includes organic compounds with more than one benzene ring, and which have a boiling point greater than or equal to 100° C. 
               
               
                   5 A type of atom which spontaneously undergoes radioactive decay. 
               
            
           
         
       
     
     A business that fails to monitor and take appropriate action to correct leaks of volatile organic compounds (VOCs), hazardous air pollutants (HAPs), Criteria Pollutants or greenhouse gases (GHGs) is taking a risk of having their operating permits suspended in addition to the possibility of incurring significant fines. As used herein, the term “volatile material” includes, without limitation, VOCs, HAPs, Criteria Pollutants and GHGs. 
     In addition to regulatory concerns, we speculate that the lost revenue of escaping VOCs and other volatile materials at the site of compression of these gases is a significant incentive to monitor compressor equipment to enable quick repair or replacement of compressor equipment in the event of detected volatile material leaks. 
     Currently within the industry, we have sometimes observed that the decision by the compressor operator regarding the timing of maintenance is left to either audible detection of volatile material leaks or physical detection of escaping gas by placement of the operator&#39;s hand on the compressor apparatus (to detect the stream of the escaping volatile material). Thus, there is a continuing need for a system that can reliably monitor and annunciate emissions of equipment, such as compressors of volatile materials such as VOCs. 
     SUMMARY OF THE INVENTION 
     In view of the aforementioned problems, it is an object of the present invention to provide a system for detecting, monitoring and annunciating volatile material leaks comprising a compressor apparatus sized and configured to compress a volatile material. The apparatus, adapted for use in a compressor, comprises a compressor cylinder containing a central space, a compressor piston, sized and configured to be slidably engaged within said central space, a compressor piston rod, attached to said compressor piston, which compressor piston rod moves through a packing case when said apparatus is in operation, and a leak detector sized and configured to detect and monitor leaks of said volatile material from said packing case. The detector comprises a housing containing a cavity in fluid communication with said packing case and with said volatile material within said packing case, a detector piston, sized and configured to be slidably engaged within said cavity and which detector piston moves within said cavity in response to increased pressure of said volatile material received from said packing case, a spring positioned within said cavity proximate to a head area of said detector piston which spring is sized and configured to be compressed by movement of said detector piston, and a pin positioned within said cavity proximate to said spring, which pin is capable of being forced to partially extend from said housing when said increased pressure overcomes resistance of said spring. 
     The system further comprises a pressure transducer in fluid communication with a transducer port of said cavity, which pressure transducer is sized and configured to electrically respond to changes in pressure of said volatile material received into said cavity. 
     Exemplary embodiments of the invention include providing a system which comprises a compressor cylinder containing a central space, a compressor piston slidably engaged within said central space, a compressor piston rod attached to said compressor piston, a packing case seated on said piston rod and contained in said central space, a detector housing with a cavity, an inlet port, an outlet port and a detector pin port, said inlet port opening into said cavity where said inlet port is in fluid communication with an interior of said packing case, a detector piston slidably engaged in said cavity with an inlet side head and a detector pin head, a pin slidably engaged within said cavity with a first end adjacent to said detector pin head and a distal end slidably engaged in said detector pin port, a spring springingly seated on said pin between said detector pin head and said detector pin port, and an outlet port in said detector housing wherein said outlet port is open or closed to said cavity with sliding of said detector piston. Said embodiment may further comprise a pressure transducer in fluid communication with a transducer port of said cavity. 
     Exemplary embodiments of the invention also include providing a system for observing discharge of a volatile material subject to government regulation of discharge into the environment. The system comprises a compressor for compressing said volatile material. The compressor comprises a compressor cylinder, a compressor piston, a compressor piston rod and packing material which packing material is capable of allowing discharge of said volatile material over time. The system also comprises a volatile material discharge detector which comprises a housing containing a cavity in fluid communication with said packing material and a detector piston which moves within said cavity as an amount of discharged volatile material from said packing material increases in said cavity, and an alert pin which extends from said housing when an amount of volatile material is present in said detector cylinder 
     The detector further comprises a spring sized and configured to permit incremental movement of said alert pin out of said housing so that a portion of said alert pin is visible when said amount of volatile material applies force to a head area of said detector piston thereby compressing said spring. 
     The system further comprises a pressure transducer in fluid communication with said cavity, which pressure transducer is sized and configured to issue electrical responses to changes in pressure of said discharged volatile material received into said cavity. Said electrical responses of said pressure transducer may be analog electrical signals or digital electrical signals. 
     In an embodiment of the invention said electrical responses of said pressure transducer are collected and stored in a computer. Said collected electrical responses may be analyzed by a computer program in said computer thereby predicting a need to repair or replace said packing material in order to decrease said discharge of said volatile material. It is speculated that said computer program would allow an operator to identify trends in the data collected by correlating gas pressure measurements made by said transducer with lost volume of gas from said compressor apparatus, thus allowing said operator to predict the optimal time to schedule a repair of said compressor apparatus. 
     Another exemplary embodiment of the invention provides a detector comprising a housing containing a cavity configured to receive and discharge volatile material received from an external source, a detector piston slidably engaged within said cavity which detector piston moves within said cavity in response to a pressure of said volatile material received from said external source, a spring positioned within said cavity which spring is compressed by sliding movement of said detector piston, and a pin which travels in said cavity proximate to said spring, which pin is capable of being forced to partially extend from said housing when said increased pressure overcomes resistance of said spring. Said embodiment may further comprise a pressure transducer in fluid communication with a transducer port of said cavity. 
     Another embodiment of the invention includes a method for assessing leaks of a volatile material subject to regulation of said leaks into the environment, which method comprises: providing a fluid connection between a volatile material compressor apparatus, capable of having a leak of said volatile material, and a volatile material leak detector; allowing transfer of a leaked amount of said volatile material from said compressor apparatus to said detector; and observing a change to said detector caused by said transfer. 
     The above and other objects and features of the present invention will become apparent from the drawings, the description given herein, and the appended claims. 
     For a further understanding of the nature and objects of the present invention, reference should be had to the following description taken in conjunction with appended claims and with the accompanying drawings in which like parts are given like reference numerals. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a side cross-sectional view of a compressor apparatus and a side plan view of a packing leak detector (PLD) in accordance with some exemplary embodiments of the present invention. 
         FIG. 2  illustrates a cross-sectional side view of a packing leak detector (PLD) in a closed position in accordance with some exemplary embodiments of the present invention. 
         FIG. 3  illustrates a cross-sectional side view of a packing leak detector (PLD) in an open position in accordance with some exemplary embodiments of the present invention. 
         FIG. 4  illustrates a cross-sectional side view of a packing leak detector (PLD) which includes a pressure transducer in accordance with some exemplary embodiments of the present invention. 
         FIG. 5  illustrates an end, plan view of a packing leak detector in accordance with some exemplary embodiments of the present invention. 
         FIG. 6  illustrates a schematic view of a packing leak detection system in accordance with some exemplary embodiments of the present invention. 
     
    
    
     The images in the drawings are simplified for illustrative purposes and are not depicted to scale. Within the descriptions of the figures, similar elements are provided similar names and reference numerals as those of the previous figure(s). The specific numerals assigned to the elements are provided solely to aid in the description and are not meant to imply any limitations (structural or functional) on the invention. 
     The appended drawings illustrate exemplary configurations of the invention and, as such, should not be considered as limiting the scope of the invention that may admit to other equally effective configurations. It is contemplated that features of one configuration may be beneficially incorporated in other configurations without further recitation. 
     DETAILED DESCRIPTION OF THE INVENTION 
     Turning now to the Figures,  FIG. 1  illustrates an exemplary embodiment of a packing leak detection system  10  for detecting, monitoring and annunciating volatile material or volatile organic material (VOC)  12  leaks from compressor apparatus  14 . As seen in cross-section in  FIG. 1 , volatile material  12  is brought into compressor cylinder  20  through a compressor inlet valve  16 , where volatile material  12  is compressed and exits through a compressor outlet valve  18 . Compression of volatile material  12  within a central space  22  of compressor cylinder  20  is accomplished by the sliding movement of a compressor piston  24  which is slidably engaged with central space  22 . As a consequence of the physical configuration and constraints of compressor piston  24 , a certain amount of volatile material  12  moves past compressor piston  24  and enters the area of compressor cylinder  20  proximate to compressor piston rod  26  upon each repetitive motion of compressor piston  24 . Power to operate compressor apparatus  14  is supplied to compressor piston rod  26  from an external power source (not shown). 
     A portion of compressor piston rod  26  is surrounded by a packing case  28  near where compressor piston rod  26  extends from compressor cylinder  20 . Compressor piston rod  26  moves through packing case  28  when compressor apparatus  14  is in operation. 
     In the exemplary embodiment of  FIG. 1 , packing case  28  is comprised of a plurality of sub-compartments  27  in series along the length of compressor piston rod  26 , where each said sub-compartment  27  contains at least one packing ring  56  which is sized and configured to prevent movement of volatile material  12  out of compressor cylinder  20  and into the environment. The final sub-compartment  29  is the sub-compartment located closest to the exterior wall of compressor cylinder  20  and includes a vent  57  such that any volatile material which gets past the plurality of sub-compartments  27  (and the packing rings  56  therein), as well as the packing ring  56  inside of final sub-compartment  29 , is collected into tubing  58  via vent  57 . Each packing ring  56  is constructed from a softer, more wearable material than that of the compressor piston rod  26 . The phrase “more wearable” means that under similar conditions of use, one material would wear away at a greater rate that of the comparison material. In an alternative embodiment (not shown), packing case  28  may comprise a single housing surrounding compressor piston rod  26  containing one or more packing rings  56 . 
       FIG. 1  also shows tubing  58  forming a path allowing fluid communication between the interior of packing case  28  and a packing leak detector (PLD) or discharge detector  30 . While a detailed description of packing leak detector  30  will be provided in discussion of  FIGS. 2-5 , a pin or alert pin  42  can be seen extending from packing leak detector  30 . Additional tubing  58 , shown extending from packing leak detector  30  at outlet port  62 , serves to direct volatile material  12  to a collection and/or disposal site. 
     In an embodiment of the invention depicted in  FIG. 2 , a cross-sectional view of leak detector or discharge detector  30  may be seen. Volatile material  12 , which has escaped from packing case  28  of compressor apparatus  14  (seen in  FIG. 1 ), is directed by fluid communication through tubing  58 , having National Pipe Thread (NPT) fittings (also shown in  FIG. 1 ), into a cavity  34  of housing  32  of leak detector  30 . In an exemplary embodiment of the present invention, housing  32  is comprised of two machined pieces of type 306 or type 316 stainless steel held together either via welding or epoxy. In an alternative embodiment, housing  32  can be comprised of two machined pieces of aluminum or of two pieces of hard engineered plastic or of any other durable, corrosion-resistant material. 
     Housing  32  defines an inlet port  60  which opens into cavity  34  and which has NPT threads to receive threaded tubing (not shown). A detector piston  36  is slidably engaged in cavity  34  and is forced away from inlet port  60  as pressure from entering volatile material  12  increases. Housing  32  also defines an outlet port  62  which opens to cavity  34  depending on the sliding travel position of detector piston  36  (described below). Outlet port  62  has NPT threads to receive threaded tubing (not shown). In an exemplary embodiment, inlet port  60  and outlet port  62  are 0.5 inches in diameter; in an alternative embodiment, said ports are 0.25 inches in diameter. 
     It is speculated that the amount of discharged volatile material  12  coming from leaking packing case  28  is directly proportional to the degree of wear of packing ring or packing material  56 . 
     Detector piston  36  is adjacent to or integral with alert pin  42 , said alert pin  42  arranged to travel in said cavity  34  and on a side of detector piston  36  opposite said inlet port  60 . Thus, they may be of unitary construction. In an exemplary embodiment, detector piston  36  is made of Teflon. In an exemplary embodiment, alert pin  42  slides synchronously with detector piston  36 . Pin  42  is slidably engaged within cavity  34  and has a first end  78  adjacent to detector pin head  74  of detector piston  36  and a distal end  80  slidably engaged in a detector port  72 . A spring  38 , sized and configured to offer resistance to movement of detector piston  36 , is located around pin  42  at first end  78  of pin  42  and seated between detector piston  36  and a bushing  68  in cavity  34 . Volatile material  12  presses against a head area or inlet side head  40  of detector piston  36  causing movement or sliding travel of detector piston  36  and detector pin head  74  and compressing spring  38 . In an exemplary embodiment, spring  38  has an R value of 1 lb per inch; however, the R value of spring  38  may be adjusted to a desired R value to meet an acceptable lost volume of volatile material. In an exemplary embodiment, spring  38  is made of a material resistant to corrosion by, and/or non-reactive with, VOCs and HAPs, for example, stainless steel or an alloy such as Inconel® sold by Special Metals Corp. 
     NPT threaded outlet port  62  provides an avenue for eventual removal of discharged volatile material  12 . Threaded tubing  58  (best seen in  FIG. 1 ) directs volatile material to a collection and/or disposal facility. 
     As may be seen in  FIG. 3 , when a pressure of volatile material  12  is sufficiently great, detector piston  36  moves, or sliding travels, and causes pin  42  to extend from housing  32  so that pin  42  is visible to an observer. A choice of spring  38  having suitable resistance properties allows calibration of leak detector  30  to quantify pressure variation of leaking volatile material necessary to cause pin  42  to incrementally extend a distance  54  from housing  32 . Marks  52  on pin  42  become visible over time as the pressure of leaking volatile material increases and as pin  42  is forced further from housing  32 . 
       FIG. 4  illustrates an embodiment of the invention wherein leak detector  30  comprises an NPT threaded transducer port  46  within housing  32  and a pressure transducer  44  in fluid communication with pathway  50  by way of channel  70 , where pathway  50  includes inlet port  60  and cavity  34 . Pathway  50  maintains fluid communication between packing case  28  (best seen in  FIG. 1 ) and cavity  34  of leak detector  30 . Pressure build up of leaking volatile material  12 , in addition to causing movement, or sliding travel, of detector piston  36 , also acts on pressure transducer  44  causing it to emit electronic responses or electronic signals communicated via electrical conductor  76  (where electrical conductor  76  may be replaced by any data transmission medium, such as wireless transmitters/receivers, optical fiber, etc). The electronic signals can be either analog or digital electronic signals. The electronic signals can be transmitted off site to monitoring and analyzing equipment. The electronic signals can also be used to trigger one or more annunciation devices such as a lights or horns. The electronic signals may comprise a message to a computer system, or may trigger a message to be sent to a computer system. In an exemplary embodiment, pressure transducer  44  is a PT4300 pressure sensor sold by TURCK, Inc. 
       FIG. 5  depicts an embodiment of the invention as shown in an end, plan view. Leak detector  30  is shown to have a pathway  50  which permits passage of volatile material  12  which has leaked from compressor apparatus  14  (best seen in  FIG. 1 ). Bushing  68  is visible surrounding pin  42 . Pressure transducer  44  can be observed in fluid communication with pathway  50  by way of channel  70 . Other instrumentation, such as hydraulic or pneumatic transducers or instrumentation, could be substituted for said pressure transducer  44 . 
       FIG. 6  is a schematic representation of an embodiment of the invention with system  10  having a compressor apparatus  14  in fluid communication  64  (for example, through tubing  58 ) with leak detector  30 . A portion or amount of leaking volatile material from a packing case of compressor apparatus  14  will be transferred to leak detector  30  which is in fluid communication  64  with pressure transducer  44 , sized and configured to generate electrical responses in the form of electrical signals when encountering a change in pressure and to audit the transfer of volatile material which these changes represent. Pressure transducer  44  is in electrical communication  66  (for example, via electrical conductor  76 ), either directly or indirectly, with a computer  48  which collects and stores received electrical signals from pressure transducer  44 . Computer  48  contains one or more computer programs suitable to analyze the received and/or stored electrical signals and to generate statistical data related to the timing, degree and/or size of the pressure variations monitored and detected by leak detector  30 . It is speculated that the data can be used to predict and optimize desirable maintenance programs for compressor apparatus  14 . 
     One embodiment of the present invention is a method for assessing leaks of a volatile material subject to regulation of leaks into the environment. The method comprises providing a fluid connection between a volatile material compressor apparatus, capable of having a leak of said volatile material, and a volatile material leak detector; allowing transfer of a leaked amount of the volatile material from the compressor apparatus to the detector; and observing a change to the detector caused by the transfer. 
     The transfer of the amount of said volatile material is from a packing case of the compressor apparatus through connecting tubing to an inlet port of a housing of the detector. The packing case surrounds a compressor piston, and packing material interior to the packing case emits the transferred amount of the volatile material which passes through the tubing into the housing through a pathway. 
     The method further comprises placing a detector piston in the housing of the detector whereby the detector piston is displaced as the transferred amount of the volatile material passes though the pathway. 
     The method further comprises overcoming resistance of a spring within the housing, which spring is configured to retard movement of the detector piston. 
     The method further comprises forcing an alert pin out of the housing as the detector piston moves, which alert pin is positioned proximate to the detector piston and whereby a change in position of the alert pin can be visibly observed. 
     The method further comprises calibrating the alert pin with marks to permit visual perception of a distance the alert pin is forced out of the housing. 
     The method further comprises auditing the transfer by aligning a pressure transducer in fluid communication with the pathway and monitoring electronic signals emitted by the pressure transducer in response to changes in pressure within the pathway. The electronic signals are analog or digital signals. 
     The method further comprises collecting and storing the electronic signals by a computer. 
     The method further comprises analyzing the electronic signals by a computer program of the computer and predicting, by said computer program, a need to repair or replace the compressor apparatus in order to decrease the leaks of the volatile material. 
     The method provides that the packing material, which surrounds a compressor piston rod, comprises at least one packing ring formed from a more wearable substance than that of the compressor piston rod such that wear to the at least one packing ring enables leaking of the volatile material from the packing case. 
     As used herein the phrase “in fluid communication with” signifies that some means of connecting the designated elements is employed, such as tubing, lines, conduit, pipes, manifolds or the like, as long as fluid can pass between the designated elements. 
     We speculate that the following Tables 2 and 3 point out the economic factors which come into play when assessing compressor equipment leaks of volatile materials. These tables were developed based on our speculation of natural gas (methane) pipeline compressor performance. Leak rates for both tables were calculated from EPA information and various psi ratings. These tables are meant to show an appreciation of the economic impact the claimed invention would have on the industry. 
     Table 2 relates to the breakeven point in months to replace packing in the pipeline compressors when the cost of natural gas is $4.00 per thousand cubic feet (mcf). The cost is broken down by size of compressor piston rod (rod) and includes parts and labor (P&amp;L). Leak rates in standard cubic feet per hour (scfh) are given across the top of the table. The breakeven point or time in months to recoup the cost of repair of the packing is shown in italics. For example, if the cost of natural gas is $4.00 per thousand cubic feet, the compressor piston rod has a 2 inch diameter and the leak rate is 150 scfh, we speculate that the time in months to breakeven would be 0.7 months. 
     
       
         
           
               
             
               
                 TABLE 2 
               
             
            
               
                   
               
               
                 Breakeven Point in Months to Replace Packing (in italics) 
               
            
           
           
               
               
            
               
                 Cost to Replace 
                   
               
               
                 Packing 
                 Leak Rates in scfh 
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
            
               
                 @ $4.00/mcf (P&amp;L) 
                 60 
                 70 
                 80 
                 90  
                 100 
                 150  
                 200  
                 300  
                 500 
                 900 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
               
               
            
               
                 1⅛″  
                 rod 
                 $321.62 
                 
                   1.9 
                 
                 
                   1.6  
                 
                 
                   1.4  
                 
                 
                   1.2 
                 
                 
                   1.1 
                 
                 
                   0.7  
                 
                 
                   0.6 
                 
                 
                   0.4 
                 
                 
                   0.2 
                 
                 
                   0.1 
                 
               
               
                 1½″  
                 rod 
                 $328.13 
                 
                   1.9 
                 
                 
                   1.6  
                 
                 
                   1.4  
                 
                 
                   1.3 
                 
                 
                   1.1 
                 
                 
                   0.8  
                 
                 
                   0.6 
                 
                 
                   0.4 
                 
                 
                   0.2  
                 
                 
                   0.1 
                 
               
               
                 2″ 
                 rod 
                 $297.66 
                 
                   1.7  
                 
                 
                   1.5 
                 
                 
                   1.3 
                 
                 
                   1.1 
                 
                 
                   1.0 
                 
                 
                   0.7 
                 
                 
                   0.5 
                 
                 
                   0.3 
                 
                 
                   0.2  
                 
                 
                   0.1 
                 
               
               
                 2¼″  
                 rod 
                 $307.82 
                 
                   1.8  
                 
                 
                   1.5 
                 
                 
                   1.3 
                 
                 
                   1.2 
                 
                 
                   1.1 
                 
                 
                   0.7  
                 
                 
                   0.5 
                 
                 
                   0.4 
                 
                 
                   0.2 
                 
                 
                   0.1 
                 
               
               
                 2½″  
                 rod 
                 $337.50 
                 
                   2.0 
                 
                 
                   1.7  
                 
                 
                   1.5 
                 
                 
                   1.3 
                 
                 
                   1.2 
                 
                 
                   0.8 
                 
                 
                   0.6  
                 
                 
                   0.4 
                 
                 
                   0.2 
                 
                 
                   0.1 
                 
               
               
                   
               
            
           
         
       
     
     Table 3, below, relates to our speculation as to the months to pay for installing a packing leak detector (PLD) in line with the pipeline compressors when the cost of natural gas is $4.00 per thousand cubic feet (mcf). As in Table 2, the cost is broken down by size of compressor piston rod (rod) and includes parts and labor (P&amp;L). Leak rates in standard cubic feet per hour (scfh) are given across the top of the table as calculated from available industry data as in Table 2. The estimated (our speculation) time in months to recoup the cost of installing the PLD is shown in italics. For example, if the cost of natural gas is $4.00 per thousand cubic feet, the compressor piston rod has a 2 inch diameter and the leak rate is 150 scfh, the estimated (our speculation) time in months to recoup the cost of installation would be 1.3 months. 
     
       
         
           
               
             
               
                 TABLE 3 
               
             
            
               
                   
               
               
                 Months to pay for Installed Packing Leak Detector (PLD) (in italics) 
               
            
           
           
               
               
            
               
                 Cost of PLD 
                   
               
               
                 @ $4.00/mcf 
                 Leak Rates in scfh 
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
            
               
                 With (P&amp;L) 
                 60 
                 70 
                 80 
                 90  
                 100 
                 150  
                 200  
                 300  
                 500 
                 900 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
               
               
            
               
                 1⅛″  
                 rod 
                 $545.00 
                 
                   3.2 
                 
                 
                   2.7 
                 
                 
                   2.4 
                 
                 
                   2.1 
                 
                 
                   1.9 
                 
                 
                   1.3 
                 
                 
                   0.9 
                 
                 
                   0.6 
                 
                 
                   0.4 
                 
                 
                   0.2 
                 
               
               
                 1½″  
                 rod 
                 $545.00 
                 
                   3.2 
                 
                 
                   2.7 
                 
                 
                   2.4 
                 
                 
                   2.1 
                 
                 
                   1.9 
                 
                 
                   1.3 
                 
                 
                   0.9 
                 
                 
                   0.6 
                 
                 
                   0.4 
                 
                 
                   0.2 
                 
               
               
                 2″  
                 rod 
                 $545.00 
                 
                   3.2 
                 
                 
                   2.7 
                 
                 
                   2.4 
                 
                 
                   2.1 
                 
                 
                   1.9 
                 
                 
                   1.3 
                 
                 
                   0.9 
                 
                 
                   0.6 
                 
                 
                   0.4 
                 
                 
                   0.2 
                 
               
               
                 2¼″  
                 rod 
                 $545.00 
                 
                   3.2 
                 
                 
                   2.7 
                 
                 
                   2.4 
                 
                 
                   2.1 
                 
                 
                   1.9 
                 
                 
                   1.3 
                 
                 
                   0.9 
                 
                 
                   0.6 
                 
                 
                   0.4 
                 
                 
                   0.2 
                 
               
               
                 2½″  
                 rod 
                 $545.00 
                 
                   3.2 
                 
                 
                   2.7 
                 
                 
                   2.4 
                 
                 
                   2.1 
                 
                 
                   1.9 
                 
                 
                   1.3 
                 
                 
                   0.9 
                 
                 
                   0.6 
                 
                 
                   0.4 
                 
                 
                   0.2 
                 
               
               
                   
               
            
           
         
       
     
     The foregoing description of the embodiments of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and modifications and variations are possible in light of the above teachings or may be acquired from practice of the invention. The embodiments were chosen and described in order to explain the principles of the invention and its practical application to enable one skilled in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. 
     This invention is susceptible to considerable variation in its practice. Therefore the foregoing description is not intended to limit, and should not be construed as limiting, the invention to the particular exemplifications presented hereinabove. Rather, what is intended to be covered is as set forth in the ensuing claims and the equivalents thereof as permitted as a matter of law.