Crit­i­cal case for re­li­a­bil­ity

DEMM Engineering & Manufacturing - - PNEUMATICS & HYDRAULICS - Go to demm.co.nz/en­quiry quote: D140825.

Pneu­matic con­trol has been in use for many years, es­pe­cially in the phar­ma­ceu­ti­cal, food and bev­er­age in­dus­tries, where hy­gienic con­di­tions must be main­tained.

Pneumatics have many ad­van­tages, in­clud­ing sim­plic­ity of de­sign, low main­te­nance re­quire­ments, and ex­cel­lent re­li­a­bil­ity due (in part) to the use of com­pressed air as the power source. In ad­di­tion, these sys­tems are in­trin­si­cally safe and so can also be used in haz­ardous at­mos­pheres, such as those in the petro­chem­i­cal in­dus­tries.

Mod­ern con­trol sys­tems can be di­vided into two groups, cen­tralised and de­cen­tralised. A cen­tralised con­trol so­lu­tion is the more tra­di­tional one and will usu­ally in­volve a con­trol panel con­tain­ing a bank of con­trol so­le­noids that are con­nected to the process con­trol valves us­ing air lines alone.

In a de­cen­tralised sys­tem, the air sup­ply is fed di­rect to the con­trol valve and the in­te­gral con­trol head uses con­trol sig­nals to de­ter­mine what ac­tion is re­quired. The choice of sys­tem is de­pen­dent on the ap­pli­ca­tion, the cru­cial point is to en­sure that the sys­tem is prop­erly de­signed and in­stalled to en­sure ef­fi­cient and re­li­able op­er­a­tion.

Once the de­sign scope is agreed, even for the sim­plest of in­stal­la­tions, it is im­por­tant to en­sure the pro­posed de­sign will pro­duce an ef­fec­tive and ef­fi­cient con­trol sys­tem which will be easy to main­tain, ex­pand, and (if nec­es­sary) clean to the re­quired stan­dard.

Although many of the com­po­nents used in a pneu­matic con­trol sys­tem are rel­a­tively in­ex­pen­sive, the cost of gen­er­at­ing the com­pressed air is not, so it is cru­cial the air is used in the most ef­fi­cient way.

This also im­pacts the ‘green rat­ing’ of your process line, which is in­creas­ingly im­pact­ing prof­itabil­ity, and be­ing re­ported on the ‘triple bot­tom line’.

The first step is to clean and reg­u­late the com­pressed air sup­ply to the con­trol sys­tem us­ing air prepa­ra­tion units that fil­ter and reg­u­late the air sup­ply. These units re­move wa­ter and oil aerosols while also con­trol­ling the sys­tem air pres­sure all of which makes them cru­cial to en­sur­ing cor­rect op­er­a­tion of the sys­tem as well as re­duc­ing wear and cor­ro­sion of the com­po­nents.

Burk­ert of­fers stan­dard­ised fil­ter­reg­u­la­tor air prepa­ra­tion units, with and with­out iso­la­tion valve kits, for all man­i­fold sizes avail­able from lo­cal stores.

Air prepa­ra­tion units are avail­able with a range of fil­ter sizes, down to 0.01μm, as well hav­ing the op­tion of an ac­ti­vated car­bon fil­ter that can re­move oil aerosols to a level of less than 0.005 mg/m3. In ad­di­tion, a range of con­nec­tion sizes is avail­able, plus ex­plo­sive en­vi­ron­ment cer­ti­fi­ca­tion to com­ply with reg­u­la­tions when op­er­at­ing in haz­ardous at­mos­pheres.

As the sys­tem starts to take shape, so there is a need for flow re­stric­tors, oneway valves and check valves to en­sure the air pres­sure and flow di­rec­tion is cor­rect for the equip­ment it is sup­ply­ing. These need to be matched to the ap­pli­ca­tion with re­gard to con­struc­tion ma­te­rial, seal­ing prop­er­ties and con­nec­tion sizes, to en­sure re­li­able and ef­fi­cient ser­vice.

Bürk­ert has de­vel­oped a wide range of prod­ucts for use in pneu­matic process con­trol sys­tems as well as a process for de­sign­ing, build­ing, in­stalling and com­mis­sion­ing com­plete sys­tems.

From the sim­plest closed loop con­trol sys­tem, to the largest fac­tory wide pro­duc­tion fa­cil­ity with the lat­est field­bus com­mu­ni­ca­tions and in­tel­li­gent con­trol valves, Burk­ert has the ex­pe­ri­ence and ex­per­tise to de­liver a range of re­li­able, ef­fi­cient and eco­nomic projects.

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