fig1 shows a typical system utilizing the control valve - visual indicator of this invention . a better understanding of the invention is realized upon understanding a simple system which utilizes the control valve . the system includes a product flowline 10 with a gate valve 12 therein . gate valve 12 has a body 14 with a gate 16 mounted therein and an opening 18 in gate 16 . gate 16 is movable between opened and closed positions relative to flowline 10 . a stem 20 is connected to gate 16 and extends through a pneumatic actuator , indicated generally at 22 . pneumatic actuator 22 includes a cylinder 24 mounted on valve body 14 . a piston 26 mounted in cylinder 24 is secured to stem 20 for reciprocating movement within the cylinder . a spring 28 mounted in the lower portion of cylinder 24 urges piston 26 and gate valve member 16 to a closed position or a raised position as the apparatus as shown in fig1 . a high - low pilot valve assembly is generally indicated at 30 and includes a high pressure pilot valve or pressure sensor 32 and a low pressure pilot or pressure movement within the cylinder . a spring 28 mounted in the lower portion of cylinder 24 urges piston 26 and gate valve member 16 to a closed position or a raised position as the apparatus as shown in fig1 . a high - low pilot valve assembly is generally indicated at 30 and includes a high pressure pilot valve or pressure sensor 32 and a low pressure pilot or pressure sensor 34 . pressure in flowline 10 is sensed through the pilot pressure sensing line 36 and passed through a branch manifold 38 to each of the pilot valves 32 and 34 . branch manifold 38 forms a structural support or mount for pilot valves 32 and 34 . each pilot valve 32 and 34 has a shiftable valve member therein and a spring urging the shiftable valve member in one direction in opposition to pressure from the source being monitored . a pneumatic fluid source 40 is connected through a pressure regulator 42 to high pressure pilot valve 32 , then by a connecting line 44 to low pressure pilot 34 . the pneumatic fluid source can be a pressurized source of air , oxygen , nitrogen gas , etc . in this disclosure for convenience , reference is made to the supply being compressed air . it is to be understood that the control valve - indicator as well as the actuator and pilot valves can be operated from a hydraulic fluid source if desired . high pressure pilot 32 is adjusted so that it is actuated at a predetermined high pressure of flowline 10 , and likewise low pressure pilot 34 may be set to a predetermined low pressure actuation point . by arranging the pressure sensors in this manner an operating fluid pressure range can be selected for flowline 10 . in the event the pressure in flowline 10 drops below or raises above the predetermined limits then the appropriate pilot valve is actuated . upon actuation of either the high pressure pilot 32 or the low pressure pilot 34 the air in line 46 from the low pressure pilot to the control valve - visual indicator , indicated generally at 50 , is interrupted and exhausted through a vent in the pilot valve and the control valve . for further details concerning the operation of pilot valves 32 and 34 reference is made to u . s . pat . no . 3 , 043 , 331 , the entire disclosure of which is incorporated by this reference . referring to fig2 and 3 wherein one embodiment of the control valve - visual indicator of this invention is shown in detail , with such being indicated generally at 52 , and including a housing 54 forming the main portion of the valve with a slide valve 51 slidably mounted therein . housing 54 has a central bore therethrough indicated generally at 53 . bore 53 is comprised of several bore portions including a small diameter portion 55 terminating at one end of the housing 54 and continuing to a midpoint in the housing where it joins an intermediate diameter bore portion 56 which continues to join a larger diameter bore portion 58 , which connects with the largest diameter bore portion 60 in the end portion of the housing . housing 54 is internally threaded in the end portion adjacent the largest bore portion 60 to receive and mount a housing end member 62 . a seal ring 64 is located at the internal juncture of housing 54 and housing end 62 . a pressure sensing port 66 is located through housing end 62 for connecting the pressure sensor to the monitored pressure line . a passageway 68 connects pressure sensing port 66 with the interior end of housing end 62 . an annular seal ring 70 is mounted in a groove around passageway 68 on the end of housing end 62 which is enclosed inside housing 54 . housing 54 is provided with a vent port 71 at a midportion thereof in fluid communication with intermediate bore portion 56 . an outlet port 72 is provided in housing 54 in a midportion thereof and connected with small bore portion 55 at a point located along small bore portion 55 and spaced from the juncture of small bore portion 55 and intermediate bore portion 56 as shown clearly in fig2 . an inlet port 74 is provided in housing 54 at a point between outlet port 72 and the housing end which has slide valve 51 extending therefrom . slide valve 51 has a small diameter portion 76 comprising a majority of the length thereof . a reduced diameter portion 78 at a midportion of slide valve small diameter portion 76 is positioned to be moved between one position in fluid communication with inlet port 74 and outlet port 72 and another position connecting outlet port 72 and vent port 71 . a piston 80 is threadedly secured to one end of slide valve member 51 at the end of the small diameter portion 76 . piston 80 has an annular groove therearound receiving and mounting an o - ring 82 for sealing in bore portion 58 . piston 80 has its diameter sized to move into bore portion 58 with o - ring 82 in fluid tight sealing relation with the bore side wall . bore portion 60 is sized diametrically substantially larger than piston 80 so that when piston 80 moves into bore portion 60 fluid can flow around the perimeter of the piston past 0 - ring 82 in the piston chamber 84 defined by bore portions 58 and 60 . a helically wound spring 86 is provided around slide valve small diameter portion 76 with one end of the spring abutting on the inner side of piston 80 and the opposite end of the spring abutting the end of intermediate bore portion 56 . slide valve member 56 has an enlongated longitudinal bore 90 therethrough connecting with at least one passageway 88 through piston 80 connecting elongated passageway 90 with the exposed end of piston 80 . passageway 88 opens on the outer end face of piston 80 at a point which is radially outward of annular seal 70 as shown clearly in fig2 and 3 . housing 54 is provided with an internal seal for sealing on slide valve member 56 between outlet port 72 and intermediate bore portion 56 . this internal seal is comprised of an annular groove in housing 54 along bore 53 for receiving and mounting an o - ring 92 at a point between outlet port 72 and vent port 71 to seal with the piston end portion 94 of slide valve member 51 when it is in the extended position as shown in fig3 . slide valve member 51 is provided with a pair of annular grooves therearound in a spaced relation in a midportion thereof mounting o - rings 96 and 98 . o - rings 96 and 98 are arranged in a spaced relation to each other and to reduced diameter portion 76 in a position such that when the slide valve is in the retracted or seated position as shown in fig2 o - ring 96 will seal between slide valve 51 and bore 60 at a point between outlet port 72 and inlet port 74 , and o - ring 98 will seal on the opposite side of inlet port 74 . these o - rings function to block flow into the inlet port 74 when the control valve is in the retracted position . a latch structure is provided on the control valve to temporarily secure slide valve 51 in the extended position for start up of a system containing the control valve - visual indicator . an annular groove 100 is provided in slide valve member 76 at a point outwardly of o - ring 98 . a latch housing 102 is mounted with valve housing 54 and contains a detent member 104 . detent member 104 is urged in an outward direction relative to slide valve 56 by a helical spring 106 positioned around detent member 104 and enclosed in latch housing 102 . in use , detent member 104 is manually pressed inwardly in opposition to spring 106 with the inner end of detent member 104 being held inwardly by spring 86 urging slide valve 51 downwardly . functionally , the latch or detent member 104 holds slide valve 51 in the extended position until fluid pressure in piston chamber 84 is sufficient to displace slide valve 51 outward a small amount when the system is properly operating after the initial start up period . the visual indicator portion of the control valve - visual indicator structure 52 is generally indicated at 110 and it is mounted on the outer end portion of slide valve 51 . visual indicator 110 includes a housing enclosing a bi - colored indicator member and other apparatus to move the bi - colored indicator member between alternate positions thereof . the indicator housing includes a mount or base portion 112 which has a bore therethrough and is internally threaded on one end to be threadedly mounted on the outer end portion of slide valve 51 . a port 114 connects the end of the threaded bore portion in housing base portion 112 to a cylindrical bore on the opposite end thereof . an indicator housing intermediate portion 116 is threadedly mounted with the exterior of housing base portion 112 and it has a cylindrical bore 118 therethrough which forms the cylinder for a piston and cylinder apparatus used for displacement of the bi - colored indicator member . an indicator housing outer end portion 120 is threadedly mounted on the outer end portion of housing intermediate portion 116 and includes a transparent cover 122 bulging outwardly therefrom . the bi - color indicator member is a substantially spherically shaped member 124 having an axis or shaft 126 positioned therethrough and a slot 128 therein substantially perpendicularly oriented relative to shaft 126 . a connecting arm 130 is secured to shaft 126 . connecting arm 130 provides an attachment point for pivotally mounting a connecting rod 132 . the exterior surface of spherical indicator member 124 is colored in two contrasting hemispherical portions with such surfaces indicated at 134 and 136 . in practice in industry it has been found desirable in some instances to color these surfaces with bright constrasting colors . for example , surface 134 can be colored red and surface 136 can be colored green . for illustration purposes , surfaces 134 and 136 are appropriately shaded to indicate red and green surfaces respectively . it is obvious that the choice of colors for the surfaces depends upon a specific application and the desire of the user . shaft 126 is mounted in a bearing journal ( not shown ) in indicator housing intermediate member 116 so the shaft will rotate substantially perpendicular to the elongated longitudinal axis of slide valve member 51 . the portion of the indicator mechanism to rotate visual indicator member 124 includes a piston 138 mounted in cylindrical bore 118 in housing members 112 and 116 , and a spring 140 . spring 140 is held on one end by a spring retainer 142 mounted in indicator housing 116 and abuts piston 138 on its opposite end to urge piston 138 toward slide valve member 51 . connecting rod 132 is pivotally mounted with piston 138 and visual indicator member 124 . movement of piston 138 between alternate positions at the opposite ends of bore 118 displaces piston rod 132 generally longitudinally relative to indicator housing 110 and thereby rotatably displaces indicator member 124 about the axis of shaft 126 . slot 128 in spherical member 124 serves as a recess to accommodate a portion of connecting rod 132 when piston 138 is moved toward the indicator member as shown in fig3 . when the pressure applied at port 114 is not high enough to overcome the force of spring 140 then indicator 124 assumes the position shown in fig2 . when fluid pressure applied to port 114 is sufficient to overcome spring 140 , then piston 138 moves outwardly away from slide valve member 51 thereby displacing connecting arm 130 and rotating spherical indicator member 124 . fig7 and 8 show an additional , or second , embodiment of the control valve - visual indicator of this invention in the retracted position and the extended position . this second embodiment of the control valve - visual indicator is indicated generally at 150 . the majority of the control valve portion of this structure is identical to that described previously and for brevity will not be repeated here . portions of this structure which are identical to that described above are given the same referenced numerals as the structure described above followed by the letter &# 34 ; a &# 34 ;. the main difference in the control valves is in the outer end portion of the slide valve member 152 where the indicator structure is located . in this embodiment of the device provisions are made for a piston and cylinder in slide valve member 152 to move the indicator member . the outer end portion of the slide valve member 152 is the only portion structurally different from the control valve shown in fig2 and 3 . slide valve member 152 has a longitudinal internal bore 154 in its outer end portion terminating at an internal abutment 156 around the slide valve internal passageway 90a . a piston 157 is slidably mounted in internal bore 154 and has an enlongated indicator member or stem 158 secured thereto extending from one side thereof . piston 157 has a peripheral groove therein receiving and mounting on o - ring 160 for sealing in bore 154 . a helical spring 162 is positioned around stem 158 with one end abutting the stem side of piston 157 and the opposite end abutting an annular spring retainer member 164 rigidly secured in the outer open end of bore 154 . indicator member 158 is sufficiently long to terminate within the aperture 172 of spring retainer member 164 when piston 157 is seating on abutment 156 . spring retainer member 164 is held in place in bore 154 by an internal abutment in a transparent cover or enclosure 166 secured by threads 168 on the outer end portion of slide valve member 152 . transparent cover or enclosure 166 is provided with an internal bore 170 . bore 170 defines a reflective zone of the visual indicator device . when indicator member 158 is moved to the extended position the shank portion thereof moves through aperture 172 into the reflective zone defined by the bore 170 of cover 166 . in regard to the coloring of the indicator member 158 , it is preferably colored some bright color which will be easily visible through the transparent cover 166 . for example , indicator member 158 can be brightly colored on its cylindrical side wall with a contrasting color on its outer end 174 . alternately , if desired , indicator member end 174 can be given a gray appearing color so that when the cover is viewed with indicator member 158 retracted the indicator has a rather neutral appearance . with this coloring scheme , a brightly colored side wall , for example green , on indicator member 158 would make the indicator have an easily distinguishable colored hue when the indicator member is extended . another coloring scheme is to color the entire indicator member 158 including end 174 a single bright color so the overall colored appearance of the indicator will be significantly changed when the indicator member is extended or retracted although it remains basically the same color . in industrial practice it is typical to choose colors for indicating devices so they appear green for a normal condition and red for an abnormal condition . with this in mind , it would be acceptable to color indicator member 158 green on its side wall and red on its end 174 . considering the other described coloring schemes , the indicator member could be colored all green or green on the side and gray or silver or some neutral color on its end . in the operation of control valve - visual indicator 150 is to be noted that the valve portion thereof will function the same as the valve portion of control valve - visual indicator 52 described above . the indicator device shown in fig7 and 8 provides a maximum color exposure when the control valve is in its normal operating condition as shown in fig8 and it provides a minimal exposure when the control valve is in its out of service or retracted position as shown in fig7 . the indicator device 110 shown in fig2 and provides a comparable degree of color exposure when it is in its normal operating position or out of service position . referring to fig1 - 3 , and concerning operation of the control valve - visual indicator of this invention , it can best be understood from a combined description of these figures . control valve - visual indicator 52 is shown in fig1 with other elements of the complete system . the system as illustrated is in its normal operating condition with gate valve 12 open and fluid pressure applied to actuator 22 through control valve 52 . the control circuit lines or connecting conduits are shown in dashed lines in fig1 . low pressure air is present in the lower portion of the control circuit from low pressure regulator 42 through pressure sensors 32 and 34 and in line 46 to the pressure sensing port 66 of control valve 52 . a higher pressure air is present in the upper portion of the control circuit where it is regulated by high pressure regulator 41 , connected with the inlet port 74 of control valve 52 and connected from outlet port 72 through line 45 to actuator 22 . this high pressure air is communicated through control valve 52 into the actuator piston chamber above piston 26 to urge it downward in opposition to spring 28 to keep gate valve 12 open . so long as control valve 52 is in its normal operating position as shown in fig3 high pressure air is communicated through it to actuator 22 . when the pressure in production line 10 raises above or drops below a predetermined pressure either the high pressure sensor 32 or the low pressure sensor 34 is tripped . when this occurs , the appropriately tripped pressure sensor vents the air from line 46 to the atmosphere and blocks the incoming low pressure air from pressure regulator 42 . once the pressure in line 46 drops , the pressure in control valve piston chamber 84 drops and spring 86 urges piston 80 to the seated position shown in fig2 . with the control valve in the position shown in fig2 incoming high pressure air is blocked at inlet port 74 and outlet 72 is connected with vent 71 so that air form the actuator piston chamber is bled to the atmosphere and valve 12 is closed . in regard to the visual indicator , it is orginally in the position shown in fig3 with the green colored surface 136 visible through cover 122 and piston 138 in the raised positon . once the pressure reduces and slide valve 51 moves to the position shown in fig2 the pressure in bore 90 is reduced and piston 138 moves to the end of bore 118 under the force from spring 140 , and more importantly , the red colored surface 134 of indicator member 124 is now visible through cover 122 . as described above , the red color will indicate to an operator that an abnormal condition exits in the system , in this instance it indicates gate valve 12 is closed . for an operator to restart the system shown in fig1 the housing of visual indicator 110 is grasped by hand and pulled outwardly thereby displacing slide valve member 51 to the position shown in fig3 . at this time , detent member 104 is pressed inward so that its inner end engages slide valve groove 100 . once this is done , the operator releases the visual indicator and the force of spring 86 on slide valve member 51 wedges detent member 104 in notch 100 to hold the slide valve member in the extended position . at this time , the visual indicator 110 exposes the red colored surface 134 because pressure in the system is not sufficiently high to displace piston 138 . as pressure rises in the air chamber of actuator 22 gate valve 12 opens thereby raising the fluid pressure in product line 10 . pressure in control valve piston chamber 84 also raises and will reach a point sufficient to displace piston 80 slightly upwardly from the position shown in fig3 so that detent member 104 is released and visual indicator piston 138 is moved to the position shown in fig3 . at this time the system containing control valve - visual indicator 52 is again in its normal operating condition . referring to fig9 such illustrates another , third , embodiment of the control valve - visual indicator of this invention . this third embodiment has the same control valve structure ( with the exception of the outermost end portion of the slide valve member ) as the control valve shown in fig2 and 3 . for brevity , description of the control valve structure will not be repeated here and portions of the control valve structure which are identical are given the same numerals as in fig2 and 3 followed by the letter &# 34 ; b &# 34 ;. the distinction between the embodiment shown in fig2 and 3 and the embodiment shown in fig9 lies in the visual indicator structure , indicated generally at 180 , and its connection with the slide valve member . in fig9 the slide valve member , generally indicated at 182 , has a longitudinal bore 184 in its outer end portion connecting with slide valve internal passageway 90b at a point well within its end portion . visual indicator 180 includes a hollow housing 186 having a sleeve portion 188 threadedly mounted on the outer end portion of slide valve member 182 . a piston 190 with a peripherally mounted o - ring 192 is slidably mounted in a cylindrical bore 193 in the inner portion of sleeve 188 . a tension spring 194 is located in slide valve bore 184 and secured on one end to spring mount pin 196 mounted transversely through slide valve member 182 and attached on its opposite end to a spring mount lug 198 on piston 190 . the indicator member is a spherically shaped member 200 , like that shown in fig5 and 6 with opposite substantially hemispherical portions thereof colored red and green as shown , pivotally mounted on a shaft 202 journalled in indicator housing 186 . a connecting rod 204 is pivotally mounted on one end to a lug 206 on piston 190 and on its opposite end to a connecting arm 208 which is enclosed in indicator member 200 and rigidly connected to shaft 202 . a transparent cover member 210 is mounted over the end of indicator housing 186 to allow visual observation of one side of spherical indicator member 200 . operationally visual indicator 180 performs similarly to the indicator device first described above . when fluid pressure in slide valve internal passageway 90b is less than that required to overcome the force of spring 194 on piston 190 then piston 190 and indicator member 200 are in the position shown in fig9 . once fluid pressure in passageway 90b increases sufficiently to overcome spring 194 then piston 190 moves to the right from the position shown in fig9 to rotate spherical indicator member 200 so that it exposes the green color . in this position the control valve is in its normal operating position . when the control valve - visual indicator is in the normal operating condition then pressure to its pressure sensing port is reduced then spring 194 moves piston 190 to the position shown in fig9 as the pressure in passageway 90b and within bore 184 are also descreased . with visual indicator 180 as with the others described herein it is to be understood that they can be colored red and green as illustrated or colored otherwise at the desire of the user . while the several embodiments shown in the drawings show the indicator element as employing different colors , it is to be understood that the indicator element which is movable between two positions , one indicating a normal operating condition and the other illustrating an abnormal condition , could be observed without the benefit of contrasting colors and our invention is not intended to be limited to the employment of contrasting colors . in the use and operation of the control valve - visual indicator of this invention , it is seen that same provides a control valve which is adequate for controlling a fluid system which is regulated in accordance with pressure . the visual indicator provides a positive indication of the pressure condition in the control valve and likewise in the system where the control valve is connected . by combining the specific control valve structure with the visual indicator in the two embodiments disclosed and described in detail herein a very useful and relatively inexpensive device has been provided for both controlling and visually indicating the pressure conditions in a fluid actuated system . the control valve - visual indicator of this invention is simple to use , made with a minimum number of components , and provides for safety in a control system by providing a clear and positive indication of the pressure conditions in the system and furthermore the control valve - visual indicator of this invention is economical in that it saves the operator time in making other tests and expending valuable time and effort to determine a present condition of a particular system .