Control components for valve automation without external piping or tubing

The oper­at­ing con­di­tions on site influ­ence the con­di­tion and func­tion­al­i­ty of equip­ment in process plants in many ways. In addi­tion to the deposits or con­t­a­m­i­na­tion gen­er­at­ed in the process, acces­si­bil­i­ty and instal­la­tion space are impor­tant cri­te­ria in ease of main­te­nance. The solu­tion to this prob­lem is a new gen­er­a­tion of con­trol devices. Instead of exter­nal attach­ments, they have an inte­grat­ed air guide as a per­fect fit for the actubar® pneu­mat­ic rotary actu­a­tors, which have a pneu­mat­ic inter­face in the top of the actu­a­tor. Plant con­struc­tion and oper­a­tion are sig­nif­i­cant­ly less sus­cep­ti­ble to faults as there is no need for any exter­nal pip­ing or tub­ing. Fur­ther­more, thanks to spe­cial air guide plates, these advan­tages can also be used for posi­tion­ers from oth­er well-known man­u­fac­tur­ers. Based on the same sys­tem and equipped with the same advan­tages, decen­tral­ized con­trols with inte­grat­ed pres­sure mea­sure­ment have also been devel­oped: a con­trol for valves with inflat­able seal and a con­trol of actu­a­tors that ensure safe and ener­gy-effi­cient oper­a­tion between air gen­er­a­tors and com­pressed air networks.
 
INTEGRATED AIR GUIDANCE ENABLES DIRECT MOUNTING OF CONTROL DEVICES ON PNEUMATIC ROTARY ACTUATORS
Pneu­mat­ic rotary actu­a­tors have long been used to auto­mate rotary valves in indus­try. How­ev­er, in addi­tion to the actu­a­tor, fur­ther com­po­nents such as pilot valves, posi­tion­ers or end posi­tion feed­back sig­nals are required to con­trol and reg­u­late valves. Until now, these com­po­nents have been con­nect­ed to the actu­a­tor via stan­dard­ized inter­faces. How­ev­er, the con­nec­tion of the com­po­nents to the pneu­mat­ic rotary actu­a­tor, which con­sists of a mount­ing bridge as well as elec­tri­cal and pneu­mat­ic con­trol and sup­ply lines, still rep­re­sents a con­sid­er­able effort. This results in cable loops and over­all com­plex pip­ing or tub­ing that must be indi­vid­u­al­ly adapt­ed to each actu­a­tor. The struc­ture always results in sev­er­al seal­ing points and thus weak points in the automa­tion solution.
Also, the known inter­faces accord­ing to VDI/VDE 3845, Part 1, require a cer­tain amount of instal­la­tion space, which has to be tak­en into
must be tak­en into account in the plant. In addi­tion, acces­si­bil­i­ty to the actu­a­tor must be guar­an­teed from at least two sides.
from at least two sides. bar GmbH has rec­og­nized the need to inte­grate and reduce inter­faces and offers cor­re­spond­ing solu­tions with the bar-vacotrol sys­tem family.
With the patent­ed actu­a­tor series actubar® the pre­req­ui­sites for the direct mount­ing of com­po­nents for posi­tion feed­back, posi­tion con­trol by means of posi­tion­er and fur­ther decentralized
con­trol sys­tems. The key to this is the addi­tion­al pneu­mat­ic inter­face on the top of the actu­a­tor. This puts pneu­mat­ics and posi­tion sens­ing on the same lev­el (Fig. 1). The new gen­er­a­tion of con­trol com­po­nents devel­oped to match this (Table 1) can oper­ate both inter­faces simul­ta­ne­ous­ly in one device. The advan­tages of inte­grat­ed air guid­ance at a glance com­pared to external
pip­ing or tubing:

• com­pact design
• few­er components
• acces­si­bil­i­ty from only one mount­ing lev­el, the top of the actu­a­tor required
• con­sid­er­able reduc­tion of assem­bly times
• Lines or cables as trip haz­ards, dirt and dust traps are eliminated
• prob­lem-free change or exchange since no pip­ing has to be adapted
• mod­u­lar system
• Reli­able and reusable seal sim­i­lar to the Namur inter­face for sole­noid valves
• Min­i­miza­tion of seal­ing points down to only one
• short dis­tances and reduc­tion of dead vol­ume in the pipelines
• Vibra­tion insen­si­tiv­i­ty Inte­grat­ed pres­sure mea­sure­ment possible

COMBINATIONS WITH COMMERCIALLY AVAILABLE CONTROLLERS VIA AIR GUIDE PLATES
In some indus­tries, posi­tion­ers from cer­tain man­u­fac­tur­ers are manda­to­ry. These are
These are long estab­lished brand­ed prod­ucts suit­able for automa­tion by means of rotary and lin­ear actuators.
lin­ear actu­a­tors. In order to extend the range of appli­ca­tion and to make the pre­vi­ous­ly described advan­tages of the bar-vacotrol sys­tem also usable in con­nec­tion with these posi­tion­ers suit­able for haz­ardous areas, a new adap­ta­tion sys­tem has been devel­oped. It con­sists of flat air guide plates with which these posi­tion­ers can also be con­nect­ed to the actubar pneu­mat­ic rotary actu­a­tor with­out the need for pip­ing or hoses. The mod­u­lar com­bi­na­tion pos­si­bil­i­ties of the bar-vacotrol sys­tem are also imple­ment­ed for third-par­ty devices with this solution.
SPECIAL CONTROL FOR COMPRESSED AIR NETWORKS AND COMPRESSED AIR TREATMENT SYSTEMS
In most plants, the inter­face between a com­pres­sor sta­tion and the down­stream com­pressed air net­work is an auto­mat­ic valve. This serves to dis­con­nect the com­pressed air net­work as soon as, for exam­ple, on the con­sumers are not in oper­a­tion, for exam­ple, at the week­end. The pres­sure con­di­tion in the net­work after sep­a­ra­tion from the com­pres­sor sta­tion is usu­al­ly not defin­able, since leak­ages occur again and again in a wide­ly branched com­pressed air net­work. Often, the net­work is then com­plete­ly vent­ed. If the auto­mat­ic valve is then opened to con­nect the net­work, very high flow veloc­i­ties can occur in the net­work. This leads to an over­load of the com­pressed air sys­tem. In this case, the refrig­er­a­tion dry­ers are dri­ven beyond their capac­i­ty lim­it and can be destroyed. In addi­tion, uncon­trol­lable amounts of con­densed water enter the com­pressed air net­work. Until now, the prob­lem has been solved by slow­ing down the auto­mat­ic valve via a heav­i­ly throt­tled pneu­mat­ic rotary actu­a­tor. This method avoid­ed the sud­den switch­ing on of the net­work. How­ev­er, in a large com­pressed air net­work, such a delay is often not suf­fi­cient in the over­all capac­i­ty. Also, dur­ing nor­mal oper­a­tion, when the net­work is not vent­ed, the appro­pri­ate­ly select­ed and adjust­ed valve also opens slow­ly, which is nei­ther desired nor nec­es­sary in this case. For this appli­ca­tion, the bar-PCS con­trol unit (Fig. 3 ) was also new­ly devel­oped for direct mount­ing. The con­sid­er­able advan­tage over the stan­dard is that bar-PCS can be oper­at­ed depend­ing on the pre­vail­ing pres­sure conditions.
The elec­tro-pneu­mat­ic con­trol unit coor­di­nates the func­tion­al sequence of the OPEN and CLOSED move­ments of the shut-off valve depend­ing on the pres­sure conditions.
shut-off valve as a func­tion of the feed pres­sure of the com­pressed air prepa­ra­tion sys­tem into the com­pressed air net­work. By means of a dig­i­tal pres­sure switch with freely pro­gram­ma­ble para­me­ters, the sys­tem is opti­mal­ly adapt­ed to the respec­tive plant. Both the pres­sure range and the hys­tere­sis of the pres­sure switch are freely selec­table and can be read via a dig­i­tal dis­play. In addi­tion, the dis­play col­or changes from GREEN to RED when the pres­sure falls below the lim­it. If the valve moves to the open posi­tion, the con­trol sys­tem imme­di­ate­ly reg­is­ters any pres­sure drop in the net­work and moves the valve back to the closed posi­tion. After the pres­sure on the com­pres­sor side has built up again and risen above the set val­ue, the valve opens again. This process is repeat­ed until the pres­sure pre­vi­ous­ly entered into the con­trol unit is reli­ably reached in the sys­tem. In this process, the net­work is filled gen­tly and con­tin­u­ous­ly, alter­nat­ing between com­pressed air sup­ply and com­pressed air com­pen­sa­tion, with­out any com­po­nents suf­fer­ing dam­age. If the pres­sure on the mains side has risen above the low­er hys­tere­sis mark of the pres­sure switch, the valve opens per­ma­nent­ly. The elec­tron­ics allow var­i­ous oper­at­ing modes and set­tings, so that an indi­vid­ual set­ting can be made can be adapt­ed to the con­di­tions in the com­pressed air system.
APPLICATION EXAMPLE WITH SPECIAL CONTROL UNIT FOR VALVES WITH BLOW-ON SEAL
In trans­port sys­tems for pow­dered media and gran­u­lates, shut-off valves are used whose ball valve, but­ter­fly valve or gate valve is equipped with an inflat­able seal. is equipped with an inflat­able seal. Automa­tion is also imple­ment­ed in these process engi­neer­ing appli­ca­tions with a pneu­mat­ic rotary actu­a­tor. In the CLOSED posi­tion, an inflat­able seal is installed between the the hous­ing of the shut-off device on the one hand or the ball, flap or slide valve on the oth­er. opti­mum seal­ing effect is achieved. Until now, the valves for this func­tion had to be equipped with exten­sive attach­ments such as sole­noid valves, pres­sure switch­es, lim­it switch­es, etc. between the actu­a­tor and the con­trols. con­trol sys­tem. This can very eas­i­ly lead to dam­age and leaks. Here again the advan­tages of direct mount­ing with­out exter­nal attach­ments, as already men­tioned at the begin­ning of this arti­cle. dis­cussed at the begin­ning of this article.
The direct­ly mount­ed and very com­pact bar­ICS elec­tro-pneu­mat­ic con­trol sys­tem was designed for this appli­ca­tion (Fig. 4). The con­trol sys­tem coor­di­nates the func­tion­al sequence of the OPEN and CLOSE move­ments of these spe­cial shut-off valves in con­junc­tion with the seal­ing pres­sure. An addi­tion­al advan­tage of using the bar-ICS is that this con­trol unit only requires the OPEN/CLOSED sig­nal and ini­tial­izes and con­tin­ues the entire sequence itself. This reduces the load on the plant con­trol sys­tem and also ensures oper­a­tional reli­a­bil­i­ty dur­ing replace­ment and retro­fitting. Via a dig­i­tal pres­sure switch with freely selec­table hys­tere­sis, the seal pres­sure for inflat­ing the seal or vent­ing can be set sep­a­rate­ly. The pres­sure switch has two switch­ing points, so that even dur­ing ongo­ing plant oper­a­tion the sleeve of the valve can be checked for leaks. This con­trol unit can be used for pneu­mat­ic rotary actu­a­tors as well as for lin­ear actu­a­tors. Here, too, the plant oper­a­tor can select the ide­al com­bi­na­tion for the pro­duc­tion process in the automa­tion of his valves. By means of freely selec­table delay times, the con­trol sys­tem can be opti­mal­ly adapt­ed to the respec­tive application.
A col­or change on the pres­sure switch sig­nals any seal defect that occurs dur­ing oper­a­tion, so that the process can be direct­ly influ­enced for inspec­tion and main­te­nance. Var­i­ous poten­tial-free LED sig­nal sig­nals for mon­i­tor­ing the actu­at­ing times and the seal­ing pres­sure of the valve round off the exten­sive func­tions of the con­trol system.
SIGNIFICANCE FOR USE IN OTHER PLANT PROCESSES
Based on the inte­grat­ed air guid­ance between the pneu­mat­ic rotary actu­a­tor and the con­trol unit
the var­i­ous applic­a­ble prod­uct solu­tions from an end posi­tion feed­back to the spe­cial con­trol of com­plex plant process­es have been pre­sent­ed here. Due to the reduc­tion of seal­ing points and the con­cep­tion as a closed sys­tem, these automa­tion solu­tions stand out from the leak­age-prone setups with exter­nal ele­ments. Exter­nal influ­ences are much less like­ly to cause dam­age and fail­ures. In addi­tion, the coor­di­nat­ed and space-sav­ing design results in a uni­form equip­ment of the sys­tems. The com­po­nents of the bar-vacotrol sys­tem, con­sist­ing of con­trol units and rotary actu­a­tors, can not only be eas­i­ly assem­bled with each oth­er as pre­sent­ed and in any com­bi­na­tion. These mod­ules can also be com­bined with con­ven­tion­al mar­ket dri­ves and posi­tion­ers. Sys­tem com­po­nents can be used to adapt to exist­ing com­po­nents in the plants. With this range of vari­a­tion and the many pos­si­ble com­bi­na­tions, the advan­tages for the plant oper­a­tor lie in the sim­pli­fied stock-keep­ing. Above all, there is the pos­si­bil­i­ty to ini­ti­ate the changeover process of the com­po­nents with­out any prob­lems and to car­ry it out in a smooth sequence. Vari­ably adapt­able prop­er­ties of the con­trol units from the bar-vacotrol sys­tem allow fur­ther indi­vid­ual devel­op­ments to be made to existing