Principles and methods of handwheel operated regulating valve

手轮, 以备在调节阀因某种非工艺原因(可能原因有仪表气源故障、调节阀膜片破裂泄漏、定位器故障、4">In concentrated nitric production site , there are many control valve equipped with a manual handwheel to prepare the non-process control valves for some reason ( possible causes instrument air supply failure , rupture of the diaphragm valve leakage , fault locator , 4 ~ 20mA output signal line failure or malfunction , etc. DCS ) , resulting in the main control room remote control valve can not operate , but the process was interrupted and therefore do not want to run , or under certain special conditions or specific conditions , can live handwheel operating control valve, manual debugging process or ensure long term operation of the device ; and in some emergency situations , can be adjusted by hand wheel valve operating device to avoid accidents or abnormal conditions prevent equipment accidents expand , then you can use hand wheel for manual control valve site .
        Handwheel types of variety, different categories and types of control valve with hand wheel on the working principle and operation using the methods vary . For a long time , craft workers rarely use hand wheel , its also poorly understood. With the valve and increasing the useful life due to failure factors, as well as efforts to achieve long-period goals for safe operation requirements , the possibility of manually operated control valve increases day by day .
        To make the process of skilled personnel to properly use the hand wheel to adjust the control valve for manual operation , especially the principles and methods of regulating valve hand wheel to make a presentation .
        A regulating valve wheel type
        In concentrated nitric workshop, equipped with a hand wheel mechanism and a more important regulator valve , the following types : .11 film linear actuators control valve FV - 206 Ammonia Ammonia oxidation-reduction valve FV - 205 I nitrate secondary air regulator valve FV - 202 I nitric oxide into the furnace air control valve SV - 101 II NOx control valve .. 2 speed gear, rack rotary actuator valve 782 M2 original oxidation furnace remote controller HV-207 bypass ammonia oxidation reduction 781 spray water valve regulating valve ( 4 units ) 661 PV - 102 into the fractionator air control valve should be noted that , FV - 205, FV - 202, SV - 101 although the diaphragm actuator straight trip, but the valve action in the form of a rotary conversion approach is the use of its stroke crank completed .
        Type 2 hand wheel mechanism and working principle
        2.1 handwheel for linear actuators of the film
        2.1.1 The top- mounted handwheel
        Handwheel top ( ie, the top film head ) in the actuator. PV - 206 are of this type , it works shown in Figure 1 . . When the handwheel clockwise , hand wheel driven diaphragm moves up the hard core and stem , leaving the seat to open the spool valve ( if positive effect gas valve closed , the hand wheel counter-clockwise rotation , the valve # 178 # LTH down core technology in 2008 the first two closed valve ) . Handwheel connection with the hard core of a larger than stem stroke neutral, when moving to the next lowest end of the hand wheel , the hand wheel does not stem effect generated force , the position of the valve stem is only the size corresponding to the input signal , which when the valve is in the remote state.
        2.1.2 The side-mounted handwheel
        Hand wheel mounted on the side of the actuator. SV - 101, FV -202, FV-205 are of this type. Side-mounted handwheel have two kinds. The working principle is based on the handwheel lever principle , there are two .
        2.1.2.1 L -type lever wheel
        SV - 101 is the type ( ASU another 3 sets ) , it works shown in Figure 2 . A hand wheel and slider are trapezoidal thread , when rotating the handwheel a slide horizontally along the handwheel handle and move around , so that b -side L -shaped around the fulcrum of the lever c d move up and down vertically , so as to drive the stem move up and down . L-shaped lever c is a point of a long hole , which is longer than the stem of the trip. When the slider bar in the center of a hole ( i.e., the pointer indicating the position / 00 scale ) , the valve stem within the full range of travel of the hand wheel not produce the force of the valve stem , when the state for the remote control valve . This hand wheel position indication window is perpendicular to the stem.
        2.1.2.2 round bar type lever
        FV - 202, FV-205 are of this type. Its working principle shown in Figure 3 . Slide a hand wheel and drive a screw through the action fan gear , when the handwheel screw driver to move up and down a vertical slider that end of the lever b c d around the fulcrum for moving up and down vertically , so as to drive up and down the stem movement. Similarly, a point of the lever c is a long hole which is longer than the stroke of the valve stem . When the slider bar in the center of a hole ( i.e., the pointer indicating the position / 00 scale ) , the valve stem within the full range of travel of the hand wheel not produce the force of the valve stem , when the state for the remote control valve . This position indicating window handwheel parallel to the valve stem. These two pieces of hand wheel locking mechanism is a / U 0 -type fork. / U 0 -type fork down card stop wheel , the hand wheel can not rotate. When you want to be operated by hand wheel , first lift / U 0 -type fork, then follow the direction of rotation indicated on the handwheel handwheel for adjusting the valve can be controlled manually .
        Rack rotary hand wheel actuator - 2.2 for gear
        Gear - rack rotary actuator piston actuator is improved products , used rotary valve , so that the kinetic energy of rotation of the stem is still piston mechanism . Works such actuators is : When the actuator for moving the piston -driven rack level , the valve stem through the gears meshing with the rack so that the stem for angular displacement . This type of valve is a total of seven units : HV-207, M 2,781 spray water ( 4 units ) , air separation PV-102. Such regulating valve works hand wheel is the same . Handwheel mounted on the bottom of the actuator , the valve stem on the right . Hand wheel and stem is / Worm - Worm 0 drive form, hand wheel and stem through which to engage or disengage the clutch control .
        When the hand wheel and engages with the valve stem rotating the handwheel , handwheel in X - Y direction of rotation , the drive stem along Z - X direction as the angular displacement so as to open or close the valve. When the handwheel is separated from the valve stem , the hand wheel forces acting on the valve stem the loss , the remote control valve is in the state . Such valve clutch depending on the model , but there is a big difference between different specifications on the installation and use of location , there are the following three kinds .
        ( 1 ) clutch with a locking device , the clutch lever on the left hand wheel . 781 four spray water valve of this type is shown in Figure 4 . At the same time when you want to use hand wheel for manual operation of the valve , first pull out the handle with your right hand while locking device , the left hand clockwise up to about 90b of the clutch lever , right hand to left hand turning the handwheel back and forth rotation clutch handles, hand wheels when obviously feel the force , then the hand wheel driven worm has been engaged with the worm on the stem , the locking device will automatically return the handle , then you can adjust the valve handwheel operation . Exit handwheel operation method is to first pull out the locking device handle right , while the left hand counter-clockwise rotation of the clutch lever down about 90b, when the locking device handle automatic back , that showed the hand wheel has been separated from the stem, then you can feel the force of the hand wheel is not obvious , and can be arbitrarily handwheel while the stem does not have an effect .
        ( 2 ) the clutch with a locking device in the hand clutch lever shaft bottom. 782M2, ASU PV - 102 valve of this type is shown in Figure 5 . Valve handwheel for manual operation of a method , in addition to the clutch lever is rotated upward about 90b counterclockwise , the other with ( 1 ) the same.
        ( 3 ) the clutch without locking device. HV-207 valve handwheel without locking means as shown in Figure 6 . Figure 6 clutch without locking device structure of this type of valve is no clutch locking device, and the clutch lever is not rotated , but pull it out to make the worm and worm gear.
        Additional features three handwheel
        Linear actuators for film handwheel addition to manually operated control valve , but also has the function of valve position limit , and for the gear - hand wheel rack rotary actuators for not having a valve position limit function.
        Principles and Methods 3.1 -mounted handwheel limit of
        2.1.1 shows the top -mounted handwheel control valve operating principle is the use of force when turning the handwheel hand wheel produced by alternative film head thrust in the air signal to overcome the effects produced by the reaction force of the spring , thereby promote stem action. When the hand wheel on the stem once had a force of the thrust and to stem in a position ( non- original position ) , then the first film role in the signal generated by the gas can only join forces with the thrust of the handwheel to make the stem continues to move in the same direction , but not in the opposite direction beyond a position . Therefore , top -mounted handwheel with unidirectional limit the role . When you need to adjust the valve top- mounted handwheel be the limit , the first signal to unload the gas within the first film , or the current signal transferred 4mA, then turn the hand wheel so that the valve stem is moved to the desired position can limit .
        Principles and Methods 3.2 side-mounted handwheel limit of
        2.1.2 shows the side -mounted handwheel control valve operating principle is a slider on the hand wheel when pushing the lever c handwheel use a side horizontally (L -type lever ) or vertically ( straight -type lever ) moves , d by the fulcrum and the other end thrust disguise the terminal b of the lever for vertical movement , so that the stem moves up and down . The slider bars on both sides of the hole can be leveraged to generate a force , that is regardless of whether the signal regulating valve , two-way valve stem can be forced to operate. Therefore , the side -mounted handwheel has a limit of two-way valve function . However , two-way valve can not limit the same time, can only choose one direction regulating valve limit . When you need to adjust the valve limit , you must first determine the limit of direction, and then to operate. If the regulating valve head the force in the same direction with the film limit , the first current signal is transferred to 20mA, and then make the handwheel stem to the desired location ; If the regulating valve head and membrane force in the opposite direction limit , the first current signal transferred 4mA, and then in the opposite direction so that the stem handwheel to the desired location .
        4 Special Considerations
        When used in gear , hand wheel rack rotary actuators , and after completion of the manual handwheel to exit the manual handwheel state, a remote control room , you must first turn the hand wheel so that the position of the main stem consistent signal output signal control room , control room , or adjust the output to make it consistent with the position of the valve stem , the hand wheel to operate the clutch and stem separation, otherwise , because of the position of the valve stem with the signal output from the main control room inconsistent, which force causes the clutch operation is difficult. Secondly, since the manual handwheel stem position determined after separation when the hand wheel , the stem will immediately change to the main control signal corresponding to the output position , and therefore , because of the mutation position and the valve stem or damage to the clutch valve.