Patent Publication Number: US-2011073200-A1

Title: Gas regulator with valve assemblies

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a Non-Provisional patent application of U.S. Provisional Patent Application No. 61/245,932 entitled “Integral Regulator Valve”, filed Sep. 25, 2009, which is herein incorporated by reference. 
    
    
     BACKGROUND 
     The invention relates generally to gas regulators, and, more particularly, to single stage and two stage specialty gas regulators. 
     Gas regulators are used in a variety of different industries and applications, such as chemical and biological laboratories, welding systems, recreational vehicles, residential and commercial buildings, and so forth. Gas regulators provide important functions in applications that require a flow of compressed air or specialty gases, such as nitrogen, oxygen, argon, helium, acetylene, and so forth, typically stored in high pressure vessels or tanks. In general, such gas regulators operate by reducing the pressure of the gas from a container (typically of highly compressed gas) to a desired level that may be adjusted manually and read on a gauge attached to the regulator. Such gas regulators traditionally include a variety of internal components (e.g., springs, plates, and washers), which cooperatively function to handle both normal operating demands and extreme circumstances. 
     A bonnet is traditionally used to contain the internal components inside the gas regulator. Such bonnets are typically made from a metal, such as brass or zinc, since the bonnets must be designed to withstand high pressures (e.g., 3000 PSI) during extreme instances of overpressurization (e.g., in case of failure of the regulating components). Metal bonnets are capable of withstanding high pressures while containing potentially broken internal components that may be produced during a failure event, and for dissipating the gas pressure in a controlled way. However, high monetary costs are often associated with the use of such metal bonnets. Accordingly, improved bonnets for gas regulators made of lighter, less expensive materials, such as 30% glass filled nylon, have been developed to reduce the monetary costs associated with metal bonnets. Unfortunately, such bonnets may have a reduced capacity to handle instances of overpressurization. For example, in common laboratory applications, an operator may mistakenly couple the high pressure gas cylinder to the outlet of the gas regulator, thus potentially causing failure of the bonnet. 
     Additionally, in some laboratory applications, high purity gas flows from storage cylinders to provide gas at acceptable levels for use in critical laboratory procedures, such as chromatography and blood analysis, which may be sensitive to contamination from atmospheric gases. Unfortunately, current gas regulators may be susceptible to such contamination, thus interfering with the quality of the results obtained via the laboratory procedures. Accordingly, there exists a need for improved gas regulators that address such drawbacks with conventional gas regulator assemblies. 
     BRIEF DESCRIPTION 
     In an exemplary embodiment, a gas regulator includes a body having an inlet, an outlet, and a seating surface disposed in an interior of the body. The gas regulator also includes a gas regulating assembly disposed at least partially in the body and adapted to regulate output pressure of gas delivered to the outlet reduced from inlet pressure of the gas at the inlet by adjustment of the regulating assembly. The gas regulator also includes a positive flow shutoff valve assembly including an adjustment extending outside of the body and adapted to be adjusted by an operator and a valve member coupled to the adjustment and disposed within the body. The valve member is adapted to move toward or away from the seating surface disposed in the body as the adjustment is adjusted to shut off gas flow through the body. 
     In another embodiment, a gas regulator includes a body having an inlet and an outlet. The gas regulator also includes a gas regulating assembly integral with the body and adapted to regulate output pressure of gas delivered to the outlet reduced from inlet pressure of the gas at the inlet. The gas regulating assembly includes a ball check assembly configured to substantially reduce flow from the outlet to the inlet when a gas source is coupled to the outlet. 
     In another embodiment, a gas regulator includes a body including an inlet, an outlet, and a seating surface disposed in an interior of the body. The gas regulator also includes a gas regulating assembly disposed at least partially in the body and adapted to regulate output pressure of gas delivered to the outlet reduced from inlet pressure of the gas at the inlet. The gas regulating assembly includes a first valve assembly including a ball check apparatus adapted to substantially reduce flow from the outlet to the inlet when a gas source is coupled to the outlet. The gas regulator also includes a positive flow shutoff valve assembly including an adjustment extending outside of the body and adapted to be adjusted by an operator and a valve member coupled to the adjustment and disposed within the body. The valve member is adapted to move toward or away from the seating surface disposed in the body as the adjustment is adjusted to shut off gas flow through the body. 
    
    
     
       DRAWINGS 
       These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein: 
         FIG. 1  illustrates a perspective view of an exemplary single stage gas regulator in accordance with aspects of the present invention; 
         FIG. 2  is an exploded view of a gas regulating assembly of the exemplary single stage gas regulator of  FIG. 1  in accordance with aspects of the present invention; 
         FIG. 3  is a perspective view of an exemplary ball check assembly in accordance with aspects of the present invention; 
         FIG. 4  is an exploded view of the exemplary single stage gas regulator of  FIG. 1  in accordance with aspects of the present invention; 
         FIG. 5  is a cross sectional view of an exemplary single stage gas regulator taken along line  5 - 5  of  FIG. 1 . 
         FIG. 6  illustrates a perspective view of an exemplary two stage gas regulator in accordance with aspects of the present invention; 
         FIG. 7  is an exploded view of a gas regulating assembly of the exemplary two stage gas regulator of  FIG. 6  in accordance with aspects of the present invention; 
         FIG. 8  is an exploded view of the exemplary two stage gas regulator of  FIG. 6  in accordance with aspects of the present invention; and 
         FIG. 9  is a cross sectional view of an exemplary single stage gas regulator taken along line  9 - 9  of  FIG. 6 . 
     
    
    
     DETAILED DESCRIPTION 
     As described in detail below, embodiments of a gas regulator including an integral valve assembly and a ball check assembly are provided. In one embodiment, the integral valve assembly is adapted to allow an operator to control an outlet gas flow by adjusting an adjustment, such as a knob located external to the gas regulator and coupled to a needle disposed within the gas regulator. The foregoing feature may offer distinct advantages over gas regulators including valve assemblies that are not integral with a body of the gas regulator. For example, embodiments of the integral valve assembly integrated into specialty gas regulators designed for use with high purity gases may reduce or eliminate the possibility of contamination of the specialty gas regulator with atmospheric gases. 
     Embodiments of the presently disclosed gas regulators may also include the ball check valve assembly. The ball check valve assembly is adapted to substantially reduce gas flow from the outlet to the inlet of a body of the gas regulator when a gas source is erroneously coupled to the outlet. That is, in instances in which the gas source (e.g., a gas cylinder) is mistakenly coupled to the outlet of the gas regulator, the ball check valve assembly may substantially prevent overpressurization of a bonnet of the gas regulator assembly. For example, in some embodiments, the ball check valve assembly may include a ball, a ball stop and a check plug. In such embodiments, the ball is adapted to be seated in the ball stop when the gas source is correctly coupled to the inlet, and flow is established from the inlet through one or more slots on the ball stop and to the outlet. However, when the gas source is incorrectly coupled to the outlet, the ball is adapted to be seated in the unslotted check plug, thus preventing gas from flowing to the bonnet. In such instances, by substantially disallowing flow from the outlet to the inlet, the ball check valve assembly may lead to the opening of a relief valve assembly and the subsequent venting of the gas to the surrounding environment. 
     It should be noted that embodiments of the integral valve assembly and the ball check valve assembly may be incorporated into any of a variety of suitable gas regulators, such as specialty gas regulators, single stage gas regulators, two stage gas regulators, and so forth. For example, the novel valve assemblies disclosed herein may be employed in the context of single stage gas regulators adapted to receive a gas from a gas source and to regulate an inlet gas pressure of the gas to an outlet gas pressure in a single step. Moreover, the disclosed valve assemblies may also be utilized in two stage gas regulators adapted to regulate an inlet pressure to an outlet pressure in two steps. Indeed, the novel valve assemblies described herein may be utilized in any gas regulator designed to regulate a pressure of an incoming gas to a suitable output pressure. 
     Turning now to the drawings,  FIG. 1  illustrates a perspective view of an exemplary single stage gas regulator assembly  10 , which is adapted to be attached to a gas source (e.g., a gas cylinder) via a suitable fixture. The gas regulator assembly  10  includes an inlet gauge  14 , an outlet gauge  16 , an outlet  18 , an inlet (not shown), a relief valve assembly  20 , an integral valve assembly  22 , a bonnet  24 , an adjusting knob  26 , and a body  28 . During operation, the single stage gas regulator assembly  10  is adapted to receive gas at an inlet pressure and to generate output gas pressure from inlet gas pressure in one step. As such, the knob  26  and the integral valve assembly  22  may be adapted to allow an operator to control the pressure and flow of the gas at the outlet. During use, as the operator adjusts the knob  26 , gas flows from the gas cylinder into the body  28  of the gas regulator assembly  10  via the inlet, and the inlet gauge  14  indicates a measurement of the pressure at the inlet. The gas is routed through internal passages of the body  28 , which are configured to regulate the pressure of the gas. For example, a gas regulating assembly disposed within the body  28  may receive incoming gas from the gas cylinder at a high pressure and regulate the gas pressure to a lower pressure suitable for use in a downstream application (e.g., a laboratory experiment, hospital or medical application, welding or cutting operation, etc.) at the outlet. As such, during use, the outlet gauge  16  indicates a measurement of the pressure at the outlet of the gas regulator assembly  10 . 
     During operation, the relief valve assembly  20  allows pressurized gas to flow out of the gas regulator assembly  10  when the pressure exceeds a predetermined limit. That is, the relief valve assembly  20  may function to vent the gas to the surrounding environment during instances of overpressurization. As such, the relief valve assembly  20  may include a variety of suitable components, such as a seat, a seat retainer, a spring, a relief valve body, and so forth. 
       FIG. 2  is an exploded view of the single stage gas regulator assembly  10  of  FIG. 1  illustrating an exemplary gas regulating assembly  29 . As illustrated, the components of the single stage gas regulating assembly  29  include the body  28 , a ball check assembly  30 , a seat assembly  32 , a stem support  34 , an o-ring  36 , a diaphragm  38 , a diaphragm washer  40 , a backup plate  42 , an adjusting spring  44 , a spring button  46 , a push nut  48 , the bonnet  24 , an adjusting screw  50 , the knob  26 , a lock washer  52 , a nut  54 , and a hole plug  56 . In the illustrated embodiment, the ball check assembly  30  includes a check plug  58 , a ball  60 , and a ball stop  62 . 
     When assembled, the hole plug  56 , the nut  54  and the lock washer  52  are threaded onto adjusting screw  50  through an axial interior channel of the knob  26 , which is secured to the bonnet  24  during use. The bonnet  24  is threaded onto the body  28  via threads  64  to form a protective housing for components  58 ,  60 ,  62 ,  32 ,  34 ,  36 ,  38 ,  40 ,  42 ,  44 ,  46 , and  48 . The body  28  is manufactured such that an internal path exists for the flow of gas through the body  28 . During operation, as the adjusting screw  50  is threaded into the bonnet  24 , the spring  44  becomes compressed between the spring button  46  and the backup plate  42 , thus increasing the gas force that must be applied downstream to oppose the spring force. Similarly, as the adjusting screw  50  is threaded out of the bonnet  24 , the spring  44  expands, thus decreasing the gas force that must be applied downstream to oppose the spring force. Accordingly, an operator may adjust the gas pressure via rotation of the knob  26  coupled to the adjusting screw  50 . 
     The single stage gas regulator assembly  29  further includes the spring button  46 , which is used to direct the movement of the spring  44  during its compression and expansion. The spring  44  is elastically deformed during compression, thus generating a variable and controllable force that determines the selected outlet (i.e., regulated) pressure. The spring  44  includes a central opening that is configured to sit on the backup plate  42 , which centers the spring  44  in the gas regulating assembly  10  and may be adapted to allow pressure to be applied to the diaphragm  38 . The diaphragm washer  40  is provided to substantially prevent the diaphragm  38  from bunching during assembly. In some embodiments, the diaphragm  38  may be made of reinforced rubber. 
     In some embodiments, the bonnet  24  may be made of a moldable synthetic plastic material. For instance, in one embodiment, the bonnet  24  may be made of 30% glass filled nylon. This feature may have the effect of reducing the monetary cost of the single stage gas regulator assembly  10  as compared to traditional systems, which may include bonnets made of metals, such as brass or zinc. However, since such moldable synthetic plastic bonnets may not be capable of withstanding pressure levels that may be contained within metal bonnets, embodiments of the present invention may include one or more features or modifications that substantially reduce or eliminate the possibility of overpressurization of the bonnet  24 . It should be noted, however, that such modifications to the gas regulator assembly  10  may be employed in conjunction with bonnets made of any suitable material, such as a moldable synthetic plastic, a metal, and so forth. 
     One such feature that the single stage gas regulator  29  may include in certain embodiments is the ball check assembly  30 .  FIG. 3  illustrates an exemplary ball check assembly  30  in more detail. As shown, the ball check assembly  30  includes the ball stop  62 , the ball  60 , and the check plug  58 . The check plug  58  includes an internal channel  66  extending axially therethrough. The ball stop  62  includes one or more slots  68  and one or more protrusions  70 . When not in use, the ball  60  is adapted to remain freely suspended between the ball stop  62  and the check plug  58 . 
     During normal operation of the gas regulator assembly  10 , gas flow is established from the inlet to the outlet in a direction indicated by arrow  72 . The flow  72  pushes the ball  60  toward the ball stop  62 , and the ball  60  becomes seated in the ball stop  62  while gas is flowing toward and exiting out of the outlet. The flow  72  is established from the inlet, through the passage  66  in the check plug  58 , around the ball  60  and through the slots  68  in the ball stop  62 . That is, the slots  68  in the ball stop  62  allow gas to reach the outlet even while the ball  60  is seated in the ball stop  62 . However, if flow is established from the outlet toward the inlet, as indicated by arrow  74 , the ball check assembly  30  is adapted to substantially prevent flow through the channel  66  in the direction of arrow  74 . For example, if a user mistakenly connects the gas cylinder to the outlet of the gas regulator assembly  10 , high pressure gas is substantially prevented from reaching the bonnet  24 . Specifically, if flow is established in the direction of arrow  74 , the ball  60  is pushed toward the check plug  58  and becomes seated in the check plug  58 , thus blocking channel  66 . 
       FIG. 4  is an exploded view of the single stage gas regulator assembly  10  of  FIG. 1 . The exploded view includes the inlet gauge  14 , the outlet gauge  16 , the outlet  18 , an inlet  76 , the relief valve assembly  20 , the integral valve assembly  22 , and the knob  26  coupled to the bonnet  24 . The inlet  76  includes a nut  78  adapted to connect to the body  28  of the regulator assembly  10  and further includes a tailpiece  80  adapted to couple directly to the gas cylinder or to a connector coupled to the gas cylinder. The relief valve assembly  20  includes a relief valve body  82 , a spring  84 , a seat retainer  86 , and a seat  88 . The integral valve assembly  22  includes a main assembly  90 , a washer  92 , and packing  94 . The main assembly  90  includes a knob  96  and a needle  98  terminating in a tip  100 . Embodiments of the present invention include the knob  96  disposed outside of the body  28  of the regulator and the needle  98  terminating in the tip  100  integral with the body  28  during use as described in detail below. However, it should be noted that in further embodiments, the inlet  76 , the outlet  18 , the integral valve assembly  22 , and the relief valve assembly  20  may include more or fewer components than those illustrated in  FIG. 4 . 
     During normal operation, gas enters the single stage pressure regulator assembly  10  from the gas cylinder through the tailpiece  80  of the inlet  76 . The gas is then routed through the gas regulating assembly in the body  28 . The gas regulating assembly is adapted to regulate output pressure of the gas delivered to the outlet  18  reduced from the inlet pressure of the gas at the inlet  76 . The knobs  26  and  96  may be utilized by the operator to determine the level of the regulated outlet pressure of the gas. As described in detail below, the relief valve assembly  20  cooperates with the ball check assembly  30  to ensure release of pressure in instances of overpressurization. 
       FIG. 5  is a cross sectional view of the exemplary single stage gas regulator taken along line  5 - 5  of  FIG. 1 . As shown, the integral valve assembly  22  includes the knob  96  and the needle  98  terminating in the tip  100 . In the illustrated embodiment, the knob  96  is disposed outside the body  28  to remain accessible to the operator for control of outlet gas flow. However, the needle  98  terminating in the tip  100  is integral with the body  28 . The tip  100  of the needle is adapted to be received by a seating surface  102  disposed within the body  28 . During operation, as the knob  96  position is adjusted by the operator, the needle  98  is configured to move toward or away from the seating surface  102  to control the outlet gas flow. For example, when the tip  100  of the needle  98  is seated flush against seating surface  102 , a compressive force substantially prevents gas leakage. 
     During use, the check valve assembly is adapted to substantially prevent overpressurization of the bonnet  24  during instances of incorrect flow, as described in detail above. For example, in the illustrated embodiment, normal flow is established in the direction from the inlet to the outlet, as indicated by arrow  104 . During such flow, the ball  60  is seated against ball stop  62  and gas flows through slots  68  toward the outlet. However, during abnormal flow, such as when an operator mistakenly connects the gas source to the outlet, flow forces the ball  60  to rest in the check plug  58 , thus substantially preventing flow into the bonnet  24 . Such a mechanism may allow the relief valve assembly  20  adequate time to open and release the high pressure gas before damage may be caused to the bonnet  24  due to extreme pressure conditions (e.g., 3000 PSI). 
     During operation, the single stage gas regulator  10  is adapted to receive gas at an inlet pressure and to generate output gas pressure from the inlet gas pressure in one step. Since the inlet pressure of the gas from the gas source directly determines the spring force on the diaphragm (i.e., the spring force on the diaphragm approximately equals the opposing force of the gas), the single stage gas regulator  10  may be susceptible to changes in the outlet gas pressure over time. For example, in embodiments in which the gas source is a gas cylinder, as the cylinder pressure decreases over time, the regulated pressure will increase. In such instances, the knob  26  may need to be periodically adjusted if a constant output pressure is desired. Accordingly, in some embodiments, it may be desirable to employ a two-stage gas regulator, as described in detail below. 
       FIG. 6  is a perspective view of an exemplary two stage gas regulator assembly  106 , which may be attached to a gas cylinder via a suitable fixture. The two stage gas regulator assembly  106  may obviate some of the drawbacks associated with embodiments of the single stage gas regulator  10 . For instance, the two stage gas regulator  106  may include a first stage that is adapted to generate an intermediate gas pressure from the inlet gas pressure and a second stage that is adapted to generate the outlet gas pressure from the intermediate gas pressure. That is, the two stage regulator  106  may be adapted to function as two single stage gas regulators operating in series, the first stage reducing the inlet pressure to an intermediate level and the second stage reducing the intermediate level even further to the output level set by the operator. As such, the intermediate pressure generated by the first stage may be susceptible to decreases in cylinder pressure, but the output pressure remains constant since the intermediate pressure is further regulated to the output pressure via the second stage. Accordingly, embodiments of the two stage regulator  106  may substantially reduce or eliminate the need for the operator to readjust the knob  26  to maintain a constant output pressure. 
     Turning now to the illustrated components of  FIG. 6 , the two-stage gas regulator assembly  106  includes the outlet gauge  16 , the inlet gauge  14 , the outlet  18 , the inlet (not shown), the relief valve assembly  20 , a second relief valve assembly (not shown), the integral valve assembly  22 , the bonnet  24 , the adjusting knob  26 , and the body  28 . During operation, the two stage gas regulator assembly  106  is adapted to receive gas at an inlet pressure and to generate output gas pressure from inlet gas pressure in two steps. As such, the knob  26  and the integral valve assembly  22  may be adapted to allow an operator to control the pressure and flow of the gas at the outlet. During use, as the operator adjusts the knob  26 , gas flows from the gas cylinder into the body  28  of the gas regulator assembly  106  via the inlet  76 , and the inlet gauge  14  indicates a measurement of the pressure at the inlet  76 . The gas is routed through internal passages of the body  28 , which are configured to regulate the pressure of the gas in two steps. For example, a gas regulating assembly disposed within the body  28  may receive incoming gas from the gas cylinder at a high pressure and regulate the gas pressure to a preset intermediate pressure in the first stage. The gas regulating assembly may further regulate the intermediate pressure in the second stage to an even lower pressure suitable for use in a downstream application at the outlet. As before, during use, the outlet gauge  16  indicates a measurement of the pressure at the outlet of the gas regulator assembly  106 . 
       FIG. 7  is an exploded view of the two stage gas regulator assembly  106  of  FIG. 6  illustrating an exemplary gas regulating assembly  108 . As shown, the gas regulating assembly  108  includes a first stage  110  and a second stage  112 . The components of the first stage  110  disposed on the right side of the body  28  in the illustrated view include the seat assembly  32 , the stem support  34 , the o-ring  36 , the diaphragm  38 , the diaphragm washer  40 , the backup plate  42 , the spring  44 , the spring button  46 , the bonnet  24 , the adjusting screw  50 , and a decal  114 . Similarly, the components of the second stage  112  disposed on the left side of the body  28  in the illustrated view include the ball check assembly  30 , a seat assembly  32 ′, a stem support  34 ′, an o-ring  36 ′, a diaphragm  38 ′, a diaphragm washer  38 ′, a backup plate  42 ′, a spring  44 ′, a spring button  46 ′, the push nut  48 , a bonnet  24 ′, an adjusting screw  50 ′, the knob  26 , the lock washer  52 , the nut  54 , and the hole plug  56 . 
     When assembled, the hole plug  56 , the nut  54  and the lock washer  52  are threaded onto adjusting screw  50 ′ through an axial interior channel of the knob  26 , which is secured to the bonnet  24 ′ during use. The bonnet  24 ′ is threaded onto the body  28  via threads  116  to form a protective housing for components  58 ,  60 ,  62 ,  32 ′,  34 ′,  36 ′,  38 ′,  40 ′,  42 ′,  44 ′,  46 ′, and  48 ′. Likewise, the decal  114  covers adjusting screw  50 . The bonnet  24  is threaded onto the body  28  via threads  64  to form a protective housing for components  32 ,  34 ,  36 ,  38 ,  40 ,  42 ,  44 , and  46 . 
     During operation, incoming gas flow is first directed into the first stage  110  to regulate the incoming pressure to a preset intermediate pressure. Compression and expansion of the spring  44  between the spring button  46  and the backup plate  42  generates a controllable force that determines the selected intermediate pressure. As with the single stage design, the spring  44  includes a central opening that is configured to sit on the backup plate  42 , which centers the spring  44  in the gas regulating assembly and may be adapted to allow pressure to be applied to the diaphragm  38 . The diaphragm washer  40  is provided to substantially prevent the diaphragm  38  from bunching during assembly. 
     Once reduced to the intermediate pressure, the gas flow enters the second stage  112  where the pressure is regulated to the desired output pressure. Specifically, as the adjusting screw  50 ′ is threaded into the bonnet  24 ′, the spring  44 ′ becomes compressed between the spring button  46 ′ and the backup plate  42 ′, thus increasing the gas force that must be applied downstream to oppose the spring force. Similarly, as the adjusting screw  50 ′ is threaded out of the bonnet  24 ′, the spring  44 ′ expands, thus decreasing the gas force that must be applied downstream to oppose the spring force. Accordingly, an operator may adjust the gas pressure via rotation of the knob  26  coupled to the adjusting screw  50 ′. 
     The second stage  112  also includes the ball check assembly  30  including the check plug  58 , the ball  60 , and the ball stop  62 . As before, the ball check assembly  30  may be adapted to substantially reduce flow from the outlet to the inlet when a gas source is mistakenly coupled to the outlet. That is, the ball  60  may be adapted to seat against the ball stop during normal operation, thus allowing flow from the inlet to reach the outlet. However, during instances in which flow originates from the outlet, the ball  60  may be adapted to seat against the check plug  58 , thus substantially preventing flow toward the bonnet  24 ′. 
       FIG. 8  is an exploded view of the two stage gas regulator assembly  106  of  FIG. 6 . The exploded view includes the inlet gauge  14 , the outlet gauge  16 , the inlet  76 , the outlet  18 , the first relief valve assembly  20 , a second relief valve assembly  20 ′, the integral valve assembly  22 , and the knob  26 . As before, the first relief valve assembly  20  includes the relief valve body  82 , the spring  84 , the seat retainer  86 , and the seat  88 . Similarly, the second relief valve assembly  20 ′ includes a relief valve body  82 ′, a spring  84 ′, a seat retainer  86 ′, and a seat  88 ′. As before, the integral valve assembly  22  includes the main assembly  90 , the washer  92 , and the packing  94 . The main assembly  90  includes the knob  96  and the needle  98  terminating in the tip  100 . As with the single stage design, embodiments of the two stage design also include the knob  96  disposed outside of the body  28  of the regulator and the needle  98  terminating in the tip  100  integral with the body  28 . The foregoing feature of the two-stage gas regulator  106  may have the effect of maintaining the purity of the inlet gas by preventing leakage into or out of the regulator body when the tip  100  of the needle  98  is seated on the seating surface  102  within the body. 
     During normal operation, gas enters the two stage pressure regulator assembly  106  from the gas cylinder through the tailpiece  80  of the inlet  76 . The gas is then routed through the gas regulating assembly in the body  28 . The gas regulating assembly is adapted to regulate output pressure of the gas delivered to the outlet  18  reduced from the inlet pressure of the gas at the inlet  76  in two steps. As described in detail below, the first relief valve assembly  20  and the second relief valve assembly  20 ′ cooperate with the ball check assembly  30  to ensure release of pressure from the first stage  110  and the second stage  112  in instances of overpressurization. 
       FIG. 9  is a cross sectional view of the exemplary two stage gas regulator taken along line  9 - 9  of  FIG. 6 . As shown, the integral valve assembly  22  includes the knob  96  and the needle  98  terminating in the tip  100 . The knob  96  is disposed outside the body  28  to remain accessible to the operator during use while the needle  98  terminating in the tip  100  is integral with the body  28 . The tip  100  of the needle is adapted to be received by the seating surface  102  disposed within the body  28 . As before, when the tip  100  of the needle  98  is seated flush against seating surface  102 , a compressive force substantially prevents gas leakage to or from the surrounding atmosphere. 
     During use, the check valve assembly is adapted to substantially prevent overpressurization of the bonnets  24  and  24 ′ during instances of incorrect flow, as described in detail above. For example, in the illustrated embodiment, normal flow is established in the direction from the inlet to the outlet, as indicated by arrow  104 . During such flow, the ball  60  is seated against ball stop  62  and gas flows through slots  68  toward the outlet. During abnormal flow, such as when an operator mistakenly connects the gas source to the outlet, gas forces the ball  60  to rest in the check plug  58 , thus substantially preventing flow into the bonnet  24 ′. When the gas is substantially prevented from flowing in a direction opposite arrow  104 , the pressure inside chamber  118  builds, and the relief valve assembly  20  opens, thus venting the high pressure gas to the atmosphere, as indicated by arrow  120 . As such, the ball check assembly  30  may react first to the improper flow path, thus allowing the relief valve assembly  20  adequate time to open and release the high pressure gas before damage may be caused to the bonnet  24 ′ due to extreme pressure conditions. 
     While only certain features of the invention have been illustrated and described herein, many modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.