US1855682A - Alarm device for fluid pressure regulators - Google Patents

Description

April 25, 1932; A. D. M LEAN 5, 8

- -ALARM DEVICE FOR FLUID PRESSURE REGULATORS Filed Feb. 19, 1951 i 2 Sheets-Sheet 1 E: M u

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ALARM DEVICE FOR FLUID PRESSURE REGULATORS Filed Feb. 19, 1931 -2 Sheets-Sheet 2 gmml oc Allen 0 Mai ean UNFTED PATENT OFFICE ALLEN I). MACLEAN, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO PITTSBURGH EQUITABLE METER COMPANY, OF PITTSBURGH, PENNSYLVANIA, A CORPORATION OF PENNSYLVANIA ALARM DEVICE FOR FLUID PRESSURE REGULATORS Application filed February 19, 1931. Serial No. 517,052.

In the operation of gas appliances it is today the common practice to distribute the gas through the mains at a relatively high pressure and to reduce the pressure in the house before the gas is allowed to flow to the gas burners, gas refrigerators or other appliances. For the purpose of reducing this high gas pressure to the lower pressure adapted for commercial and household use,

, a gas regulator, is ordinarily used which is ordinarily equipped on its low pressure or outlet side with some form of' a pressure relief device to give relief in case of an excessive pressure in the low pressure side. This safety device is ordinarily a liquid seal, usually composed of a liquid of high specific gravity such as mercury which is so placed that under the ordinary low pressure existing in the outlet pipe of the regulator it is allowed to remain in place, but should an excessive pressure he developed, this liquid is displaced in the seal or the seal is blown. This displacement of the liquid permits the gas to escape to a safe outlet by bubbling up through the displaced mercury as described more fully below, so that the gas under pressure is discharged without injury to the regulator. These seals may be formed as an integral part of the regulator or may be a separate and distinct part therefrom.

When a seal has blown and the gas under excessive pressure has escaped to the safe discharge, usually into the atmosphere, ordinarily there is no automatic resetting of the seal and the gas continues to escape to the atmosphere since there is no seal to prevent its escape. This is disadvantageous for many reasons, for example, it is a continuous loss of gas to the outer atmosphere and since this gas is usually unmetered, since the gas goes through the regulator before going through the meter the loss falls directly on the company supplying the gas and no accurate measurement can be made of the quantity of gas lost by escaping. This is also a source of considerable danger as the escape of this highly inflammable fluid into the atmosphere presents a fire hazard of some proportions. This loss of gas through the broken seal of the regulator also greatly diminishes the quantity supplied to the meter and appliances and there will probably not be enough gas flowing to carry the load. This is especially true when the source of the leak that occasions blowing of the seal remains uncorrected, for often in a well designed seal, when thesource of the leak is corrected the mercury will reseal itself. I

For these reasons it is highly desirable that when a seal is blowing some indication be given to the user of the gas in order that the gas company may be notified and a repairman may replace the seal. With this in mind, my invention herein disclosed has solved this problem by this compact, cheaply constructed, sturdy, alarm device which gives both an audible and a visual signal to the gas user when the pressure regulator seal is blown.

The device gives both an audible and a visual signal when the seal is blown; that is, an audible signal is sounded during the period in which the fluid is escaping, and a permanent visual indication is given by means of a flag which is rotated by mechanism actuated as a result of the fluid discharge, and may be noticed by the user in its danger or blown position. The meter reader in making his regular Inonthlyinspection to read the meter will also notice that theseal is blown and willreport it to the distribution department of the gas company. The audible alarm may be by means of the ringing of a bell but in some of my disclosed constructions advantage is taken of the resonating properties of the casing of thegas meter itself, and the noise is emitted by the clapper striking against the meter casing. By this expedient, a distinctive sound visible" indicator will show the meter readerthat sometime during the month the seal has blown, even. though the fact that the audible indicator had" operated would not be called to the'atten'tion of the gas company. This is an important aspect of the invention because once a regulator has started to give trouble of this nature, it may not be giving trouble at the time an inspection ismade, but may be consumer.

blowing the seal at other times and the seal automatically resetting after each blowing. A'scarred valve sometimes seals and at other times it fails to permit a resealing of the mercury. This visible indicator is in effect a device which tells if trouble has ever occurred with that pressure regulator, even if the trouble does remedy itself and the system functions satisfactorily after the trouble has occurred.

-My device is formed with a diaphragm which is actuated by the escaping fluid and this diaphragm operates a relief valve which permits the fluid, in many cases a highly inflammable gas, to escape to a safe point of discharge. The device is so constructed that the diaphragm must be raised an appreciable amount before the vent valve is opened and because of the construction the alarm is not operated by minor fluctuations in gas pressure such as always exist around a pressure regulator device. The flexible diaphragm in my device is urged by the gas against the action of a spring and the resilient dia phragm action throttles to some extent the escaping fluid and allows it to be vented through the outlet port with less violence with the pressure somewhat reduced, and in a steadierand more uniform stream. This materially reduces the danger of damage due to the explosive eflfect of the escaping fluid and lessens the dangers of the gas becoming ignited due to its rapid issuance and consee quent friction developed.

Another important object attained by my device is the furnishing of an audible indication of the blowing of the seal without interfering with the burning of the gas by the p The excess gas delivered to the regulator is the gas that operates the alarm and the regular quantity of gas is available to supply the consumers needs. Another feature of the invention is that the intensity of the audible alarm, or the numbers of impacts against the resonator given by the alarm device per minute is approximately proportional to the volume of gas which escapes through the seal. In this way an index of the magnitude of the leak is furnished by the intensity or rapidity of the alarm signal, which manifests itself by diiferent pitches of the sound, varying from a low pitch for small volumes of gas to a high pitch or shrill sound for large escaping volumes. This is an important feature of the invention and is one that is of great importance in furnishing a readily ascertainable index as to the size of the gas leak through the seal.

I have disclosed in this application three modifications of my automatic pressure relief alarm and wish it to be understood that while in the drawings I have shown its use in conjunction with the fluid pressure regulator in a gas distributing and metering circuit, my device is not limited to use in conjunction with a fluid pressure regulator or with a meter, but may beused in any installation or system which is subjected at times to a sudden excess of fluid pressure. Such conditions may and at times do occur in dispensing systems for water or other liquids and my device is not in any senseto be limited to installations in which the fluid is gaseous nor to the particular arrangement shown, which is merely illustrative of one use of the alarm.

In the drawings which are attached to this specification and form a part thereof, Figure l'is-an elevational View of the pressure regulator and meter'connections showing my seal alarm. installed so as to give an audible signal against the meter casing.

Figure 2 is a top plan view of one form of my seal alarm.

Figure 3 is a cross-sectional view taken on the line 33 of Figure 2.

Figure 4c is a vertical cross-sectional view of a modification of my seal alarm.

' Figure 5 is a vertical crosssectional view of another modification of my device.

Figure 1 shows the general arrangement of the low of circuit containing the seal alarm and in that figure, 10 is the gas inlet to pressure regulator 11 provided with outlet 12, leading through pipe 13 to inlet pipe 14% ofvany standard form of gas meter 15, although a standard tin meter is preferred. After the gas of which the pressure has been regulated is measured by meter 15 it emerges through outlet pipe 16 and from thence flows to the appliances being supplied. This pressureregulator 11 is of any well known form, and in this case is of the type containing a built-in mercury seal shown in section at 9, the operation of which is described below. The vent pipe 17 of the mercury seal is in communication through pipes 18 and 19 and elbows -20 and 21 with the seal alarm 22. This alarm is provided with an outlet pipe 23 leading to a safe exhaust for the dissound and make an audible sound,the dished side 26 of meter 15. At. 26is shown the visual indicator of the alarm, of which sub sequent description. will be made. Figure 1 is illustrative of the usual arrangement of my alarm in circuit with gas regulating and gas measuring devices and is to be taken as illustrative and not limiting of a circuit arrangement containing my seal alarm.

The operation of such a mercury seal as shown in section at 9 in conjunction with the pressure regulatorll is as follows: As shown the seal comprises a mercury retainer or cup,

divided centrally by a partition 9 which does not extend all the waydown to the bottom of the mercury well of the seal. In this way communication is maintained between the two chambers thus formed, one on either side of the dividing partition 9, thus forniing in effect a mercury U-tube. YVhen. there is an excess pressure on'one side of this U- tube the mercury is forced downwardly in the'high pressure side and upwardly inthe low pressure side until the gas reaches the bottom of partition 9 and can thus escape underneath the partition and bubble upward-' ly'through the mercury and escape into the low pressure side of the, regulator, in this case into vent pipe 17. If the leak of gas yielding an excess of pressure is a slow one the seal operates to allow a small bubble to go by from time to time and immediately thereafter the mercury will reseal itself due to the natural tendency of a liquid in a U-tube to attempt to seekits own level. If the leak is a large one the bubbles will pass so rapidly that the mercurywill be held almost entirely on the low pressure side of the U-tube and there will be a continual gurgling of the mercury. If the source of the leak is corrected the mercury will in a well designed seal, reseal itself, due to the natural tendency of a liquid to seek its own level. This displacement of the mercury in the seal and the consequent bubbling out of the gas is known as the blowing of the seal and attention is direct-ed to the .fact that when a seal is said to have blown, it does not mean that the liquid seal is blown entirely out. The liquid is merely displaced and will very frequently reseal itself when the conditions permit. It might be here pointed out that this gurgling action of the gas ingoing through the mercury seal aids in the action of the alarm device described subsequently, as it tends to move the diaphragm of the alarm back and forth thus helping the audible and visual signals.

The operation of this alarm device circuit is as follows: In normal operation of the dis tribution and metering system, the gas flows in through pipe 10 into fluid pressure regulator 11 where the pressure is regulated. The .gas then flows into the meter through pipe 13 and out through pipe 16. lVhen the liquid seal or other pressure responsive relief valve in the pressure regulator 11 is caused to operate, the escaping fluid flows out through pipes 18 and 19 into the alarm 22,

whence it is allowed to escape through thepipe 23 to a point of safe discharge. This alarm device 22 may be of any one of the forms disclosed in this application but in this illustration the particular modification.

of the device shown in Figure 5 is included.

When the diaphragm and valve mechanism are actuated by the escaping fluid in the manner disclosed subsequently in this specification, clapper arm 24 and clapper ball 25 are vibrated to impact against the meter casing 26 and yield an audible signal. Atthe same time the visual indication 26' is swung or rotated to yield a visual indication that the device has operated.

In the modification shown in Figures 2 and 3, which is the preferred modification of mydevice, the clapper ball 25 is shown-contacting and ringing bell 27 instead of striking directly on the meter casing as in Figure 1. Clapper 25-might however be extended outwardly as in that figure to contact with the side of the meter. In Figures 2 and 3, 28 is the seal alarm inlet into which pipe 19 of Figure 1 leads the gas. This inlet part is formed in member or casting 29'which also contains outlet 23 which leads to the safe gas outlet. This casting 29 is formed with a central chamber 30 provided with an aperture in the portion thereof into which headed screw 31 is inserted. Removal of this screw permits the removal of dirt or gummy subare inserted in order to secure the cover plate 35 to the lips 38 formed on the upstanding sides 34 of the casing. Centrally dividing the chamber 33 is the horizontally extending diaphragm 39 with diaphragm pans 40 and 41 stiffening it. The diaphragm is securely lield at its periphery between flange 36 and The diaphragm stem 42, the lower portion 42 constituting the valve stem, extends vertically through the diaphragm and diaphragm pans to which it is secured by the two bolt nuts 43 and 44. The diaphragm stem extends outwardly through aperture 45 in the top dished casing member 35 and at 46 the clapper arm 24 extends through a slot or hole in the valve stem. At the upper end the valve stem 42 is in contact with pivoted iio whereby it is attached to thecasing member. by rivets 51' and 52. This flag 47 is'painted a bright distinctive color so that it attracts attentionand its position is readily noticed and it is adapted to be readily rotated from its normal horizontal position by any raising or lowering of the diaphragm stem 42. The

projection 49 on the bracket 49 provides a.

stop limit movement of the clapper arm'24. Below the diaphragm and pan assembly the diaphragm stem 42 extends into an elongated bore opening 53 formed in the valve member 54. A small helical spring 55 is .po-

sitioned in this bore 53 and surrounds the lower end of diaphragm stem 42. .A cap 56 is positioned on the lower end ofithe diaphragm Stem 42. phragmassembly and the valve 54 is positioned the pin 57 which passes through apertures in valve member 54 and passes through a slot 57 formed in the valve stem 42'. The helical spring 55 extends between cap 56 and pin 57.

The valve 54 is formed with an upper clamping part 54 and a lower threaded portion 58 of smaller diameter than the upper clamping portion. The lower threaded. portion 58 is adapted for the reception of a guide supporting ring 59 from which depend the valve guides 60. These guides 60 are arranged in spider-like arrangement and are adapted to slide on surface 61 of the cylindrical opening formed in the casting 29 by upstanding side walls 62. The upper ends ofthese side walls '62 form the valve seat of the valve and this opening is adapted to be closed by valve disc 63 of. fiberor rubbercomposition. This valve disc is clamped in position on the valve assembly by valve member 54 and ring 59. It will thus be seen that the valve opening is between valve disc 63 and valve seat 62.

In operation, the alarm device as shown in Figures 2 and 3 operates as follows: The pipe19 from the fluid pressure regulator leads the fluid in through inlet 28 and upwardly through opening .32 into chamber 33. When the seal'is blown in the pressure regulator, or an unusual flow of fluid under pressure enters the chamber 33, diaphragm 39 is lifted by the fluidagainst the action of spring55. .When this spring is compressed a suflicient amount between the cap 56 on the valve stem and pin 57, the lifting force is transmitted to valve 54 andthis member is lifted, opening the discharge outlet between disc 63 and vent 62. The'opening of this valve permits the fluid to pass out through outlet 23 and the pressure is thus reduced in'chamber 33. IV hen the pressure is reduced, the diaphragm drops due to its weight and again the valve 54 is closed. Ontheupward movement of the diaphragm,

Intermediate the dia-- the diaphragm stem. which moves with, the

diaphragm'and through which clapper. arm

24 extends is moved upwardly and since on indicator about the pivot point 48. Thus this.

flag is turned to the danger or blown position. When-the diaphragm falls the diaphragm stem 42 falls carrying with it'clapper arm 24 and clapper ball 25 is caused to impact against and ring bell 27.

When the valve54 is again closed the fluid pressure againbuilds 'up in chamber 33, diaphragm'39' is again raised: and the cycle. is again repeated with the exception that the visual indicator having been operated is not effected by the second and subsequent lifting of the diaphragm stem. In this waythe:

bell is continuously rungduring'the time the fluid discharge is taking place due to the blowing of the seal or other cause.

In the modification shown' in Figure 4 an auxiliary sealing diaphragm 64 is used. The. function of this diaphragm isto effectively seal thelower end of the diaphragm stem 65', so that. gas leakage is prevented without the necessity ofproviding the stem with a stuffing box. In this modification the main diaphragm of sheepskin 66 is peripherally held between upper dished casing member of.

pressed steel 67 and lower body casting by meansofbolts 69. The body is formed to re ceive gas inlet'pipe-7O leading from the seal vent pipe and is formed .with a threaded aperture in the bottom to receive the valve supporting casting 71. This casting 71. is apertured at 72 to receive outlet pipe 73 leading to a safe exhaust. The bottom. casting 71 is provided with extending lips 74 which bear up against body casting 68and form a gastight connection. The diaphragm 66 is formed with. diaphragm pans 75 and 76 on either side of it and the valvestem65 extends through it and is attached to the pans by bolts 77 and 78.

The annular valve member. 79 isprovided with a valve disc of leather, fiber or rubberized material 80 and a threaded depending annular portion 81. This depending bore 81 has screwed thereon the seal diaphragm supporting casting 82' which is formed with valveguides 83 arranged in spider-like formation and which contact the inner wall of bottom casting 71. .At thelower end of member 82, seal diaphragm 64 extends, and is retained in place by diaphragm seal ring. 84 and screws 85 which are-driven into extended lip portion 86 of casting 82. The diaphragm stem 65 extends through seal diaphragm 64 and is secured thereto in gastight relation by bolt nuts 87 and 88. Midway on diaphragm stem 65 is pickup pin 89 which extends. through. the valve stem, a short distance below the lower edge of annular portion 81. Between this pickup pin 89 and the shoulders 89 on the pickup pin 89. will contact annular valve 7 9, extends the helical spring 90. The arrangement is such that the valve stem must be lifted a short distance by diaphragm 66 against the action of spring 90 before the portion 81 and thus open the valve.

Diaphragm stem 65 extends through a hole in casing 67 and bears against clap er arm 91 and actuates it. Clapper arm 91 is pivoted at 92 to a bracket 93 welded to the top casing member 67. Arm 91 is bent downwardly, to form lower vertical portion formed with clapper ball 94: on the end of it. This clapper arm and ball is adapted to strike against dished top 95 of gasmeter 96.

Arm 91 is adapted when lifted, to contact with hook 97 which is rigidly attached at pivot pin 98 to a visible indicator or flag member 99 painted in bright color. This indicator 99 is adapted to rotate with pivot pin 98 which is journaled for rotation in bracket 100 welded to the cover 67 and supporting the indicator and hook. W'hen arm 91 is raised by diaphragm stem 65, the arm contacts with hook 97 and so throws indicator 99 to a position other than its normal upright position. WVhen this indicator is rotated it gives a visual indication that the pressure relief device has operated.

The operation of this form of my device is similar to that-of the first disclosed modification. When the diaphragm 66 is raised by the fluid pressure, it is raised against the action of spring 90 and this spring must be compressed to some extent before the pick- -up pin 89 contacts with the valve body and lifts the valve off its seat. The pivoted visual indicator 99 is swung when the diaphragm stem 65 is raised, through the contacting of arm 91 with-hook 97. This flag 99 is swung to the blown or danger? position at the first lifting of the diaphragm stem and the audible signal is given by ball 94 impacting against meter side 95 which distinctive meta-llic sound occurs during the entire time the seal is blowing. The advantage of the seal diaphragm construction 64 is that the necessity of a stulfing box around the stem is avoided. r

In the modification shown in Figure 5 the sealing diaphragm'is placed above the valve and the spring is'positioned above the main diaphragm. In that modification 101 is the top cover or dished casing member which is T bolted at lip 102 to body member 103 which maybe made of brass tubing by bolts 10 1. Diaphragm member 105 of oiled sheepskin is clamped in position at its peripheralportion between members 102 and 103. diaphragm is stiffened and retained in place between diaphragm pan 106 and a sheet iron The diaphragm stem 108 exwasher' 107. tends through an aperture formed in top casing 101 and at its lower end through the diaphragm assembly to which it is secured by The bolt nut 109. Below the diaphragm valve stem 110 is screw-threaded at its upper end and screwed into retaining member 111 which is pressed tightly up against the diaphragm washer 107. At its lower end valve stem 110 is also screw-threaded and a brass washer 112 and a bolt nut 113 are supported on the lower end of the valve stem.

The brass body member 103 has secured to it by machine screws 114, the bottom plate member 115 also preferably of brass. Between the two members 103 and 115 is placed a gasket 116 of pulpboard, fiber, or similar material, to render the whole assembly gastight.

The bottom plate 115 is apertured at 117 for the reception of inlet pipe 118 which connects the seal alarm with the regulator seal vent pipe. The plate 115 is also formed with a threaded aperture 119 adapted to receive the valve seat supporting member 120, also preferably formed of brass. This member 120 is itself apertured for the reception of threaded outlet pipe 121 leading to a safe discharge point for the fluid. The upper annular surface of this member forms the valve seat 122.

Valve member 123, also preferablyof brass, is formed with a lower depending threaded bore portion 12 1 on which is screwed the member 125 which supports the valve guides 126 which are arranged in spider-like formation and which slideagainst the inner face of member 120. The valve closureproper is a valve disk 127 which may be formed of lea-thler, fiber, or any other desirable m'aterla Valve stem 110 extends through the aperture formed in thisvalve element and a seal on the valve stem and this forms a relatively gastight connection. The seal diaphragmis secured at its peripheral portion to the upper annular end surface of valve member 123 by means of diaphragm seal ring 131 and brass machine screws 132, thus forming a gastight connection; r

Between the under surface of valve 123 and the washer 112, inside the cavity in the annular bore portion 124, isplaced helical spring 133 which forms a yieldable element between the two. It will be noted that in order'for valve stem 110 to lift the valve, the stem must be lifted an appreciable amount, against the action of spring 133unti1 the washer 112 contacts with bore portion 124.

Above the main diaphragm and between diaphragm pan 106 and cover 101 extends the helical spring 134 which forms a resistance to free motion for the diaphragm 105. The upper part of diaphragm stem 108 extends'through the casing 101 and contacts at its upper end with visual indicator 135 pivoted at 136 to bent bracket 137, which is securedto cover 101. Spring clapper arm 138 is-secured atvbent portion 139 by belt 104 and is provided at its end with a ball 140. It is coiled as at 141 to give it greater resiliency and goes through an aperture formed in diaphragm stem 108 as shown at 142. hen stem 108 is raised and lowered ball 140 contacts 'withdished side 143 of the gas meter 144 and soproduces an audible signal.

The operation of this modification is similar-to that of the other described constructions. 'The fluid entering through conduit 118 raises diaphragm 105 and diaphragm stem allows the gas to escape.

closing and openingof the valve 123 the metallicaudible signal is obtained by the impact of ball 140 against meter casing 143. Thls noise continues duringthe time the fluid is "passing through the alarm.

It will be noticed that because of the delayedaction in the opening of the valve in all "three constructions, the alarm is operated only when there is an actual necessity for it due to an appreciableiexcess pressure. This is an important feature and prevents a mere variation in pressure due to leakage through the seal or from outside disturbances from jiggling the valve open and shut and glvlng a fa'lsealarm These minor variatlons in pressure always occur around a pressure regulator and would be a. source of considerable nuisance if the alarm were-operated by them when no realexcess pressure existed nor had operation of the pressure relief device occurred.

- In the description ofthis device I have used the term casting or have described the parts V as made of brass, b'ut'I want it to be understood that this does not limit the material to a simple, cheaply constructed, durable seal alarm, readilyadaptedxfor insertion in the.

be'used-as the alarm might be formed of cast iron or othercast metal, or from brass or any other desirable structural material as the.

"that particular installation.

Ihus it will be seen that I have developed metercircuit. 'The alarm isdeSigned not existing gas distributing system.

only to-givea permanent visual signal in case of the blowing of a regulator seal, but also gives an audible signal whichcanbeheard by the household orgas user during the time in tion is directed to the existenceof the gas discharge into the atmosphere :and the -resultinginjurious effects.

It will be noted that the seal alarmis autoed-in a fluid pressure regulator meter circuit withoutextensive repiping or change in the is intended that the above .modifications :and .arran gements of myldevice. are illustrative and not limiting and the scope ofthe invention is not tobe'limited by the disclosurevbut by the scope of the appended claims.

What I desire'to secure by Letters Batent of-the United States. is:-

1. An alarm device :for use in aifluid supply system, .the said alarm yielding .a visual signal while thealarm is subjected to :anexcessive fluid pressure, which visual signal is in evidence until the alarmis'reset.

2. An alarm device for .a fluid pressure regulator containing a liquid seal, which alarm device is adapted to give .a permanent visual indication and an audible indication during the time of blowing in the event the liquid seal of the regulator is blown-due .to an excessive fiuid pressure.

3.:1Analarm device adaptedgto give .a visual and an audible indication when subjected prisinga pressure. actuated diaphragm, 21- diaphragm stem supporting a valve assembly and adapted to actuate the indicator mechanism, :the said valve assembly being lifted off its seat to open thev valve :for the escape of the fluid when the diaphragm is raised due to the excessive fluid pressure, the visual indicator mechanism remaining in indicating position until reset.

. 4. .The structure defined in claim 3 .in which the visual'indicator comprises a .pivoted vaneand theaudible indicator comprises a clapperand resonator.

5. The structure defined in claim 3 in which the pressure actuated diaphragmis yieldably held against movement by a-springand the diaphragm stem is provided with aseal diaphragm to render the assembly fluid-tight.

6. In an alarm device adaptedto yield an indication when subjected to an excessive fluid pressure, a pressureactuated diaphragm, a diaphragm stem extending through said diaphragm, a valve seat with a valve adapted ,when opened topermit the escape ofthe fluid vunder excessive pressure, a valve stem ex- 125 tending through 'sald valve assembly-and ldlS- posed in operative relationship with said .diaphragmstem, a pickup element formed on said valve stem and adapted to raise the valve off its seat when the diaphragm and 'whichthe seal is blowing. In this'wayvatten matic in its ope-ration and isreadily insert-3' to an excessive fluid pressure, saidalarm .com-

diaphragm stem are lifted by the fluid under pressure.

7. The construction defined in claim 6 together with a visual indicator Operated by movement of the diaphragm stem.

8. The construction defined in claim 6 together With a clapper arm adapted to strike a clapper element formed on the end thereof against a resonator upon movement of the diaphragm stem.

9. The construction defined in claim 6 in which the resonator comprises a meter casing.

In testimony whereof I afiix my signature.

ALLEN D. MACLEAN.

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