Sta­bil­ity in high hu­mid­ity

DEMM Engineering & Manufacturing - - FRONT PAGE - DE­TAILS, TOM ALDRIDGE – BU MAN­AGER IN­STRU­MEN­TA­TION EUROTEC LTD EMAIL: TALDRIDGE@EUROTEC.CO.NZ

Con­tin­u­ous high rel­a­tive hu­mid­ity (RH) can im­pair the long-term sta­bil­ity and ac­cu­racy of hu­mid­ity sen­sors. There­fore, the new EE211 hu­mid­ity trans­mit­ter from the Aus­trian sen­sor spe­cial­ist E+E Elek­tronik fea­tures a heated sens­ing probe. This leads to best ac­cu­racy and long-term sta­bil­ity in high-hu­mid­ity (>85% RH) and even in con­dens­ing en­vi­ron­ment.

The EE211 is de­signed for ac­cu­rate hu­mid­ity and tem­per­a­ture mea­sure­ment un­der con­tin­u­ous high-hu­mid­ity or con­dens­ing con­di­tions. The de­vice is ideal for cli­mate con­trol in fruit and veg­etable stor­age, in green­houses, in­cu­ba­tors, ripen­ing pro­cesses or in mush­room grow­ing.

HEATED HU­MID­ITY PROBE

In or­der to avoid drift ef­fects due to long-term ex­po­sure of the sens­ing el­e­ments to high hu­mid­ity, the sen­sor head of the EE211 hu­mid­ity probe is con­tin­u­ously heated. The per­ma­nent over-tem­per­a­ture leads to max. 80 per­cent RH at the sen­sor. Con­den­sa­tion- re­lated dirt de­posits as well as cor­ro­sion of the sen­sor are thereby pre­vented.

Fur­ther­more, the unique E+E pro­tec­tive coat­ing also pro­tects the ac­tive sen­sor sur­face from con­tam­i­na­tion and cor­ro­sive in­flu­ences.

The com­bi­na­tion of these fea­tures re­sults in con­sid­er­ably im­proved long-term sta­bil­ity and in­creases both the ser­vice life and the mea­sur­ing per­for­mance of the sen­sor.

MEA­SURED VAL­UES AND IN­TER­FACES

The EE211 cal­cu­lates the dew point tem­per­a­ture ( Td) based on the RH and tem­per­a­ture val­ues mea­sured by the heated hu­mid­ity probe. A sep­a­rate, in­ter­change­able tem­per­a­ture probe mea­sures the am­bi­ent tem­per­a­ture ( T). From Td and T the EE211 cal­cu­lates back the am­bi­ent rel­a­tive hu­mid­ity as well as ad­di­tional phys­i­cal quan­ti­ties like ab­so­lute hu­mid­ity, mix­ing ra­tio, wet- bulb tem­per­a­ture or spe­cific en­thalpy.

The mea­sured val­ues are avail­able on the Mod­bus RTU in­ter­face or on two ana­logue cur­rent or volt­age out­puts. The op­tional back­lit dis­play can show up to three mea­sure­ments si­mul­ta­ne­ously.

EASY CON­FIG­U­RA­TION AND AD­JUST­MENT

The Mod­bus RTU pa­ram­e­ters, the scal­ing of the ana­logue out­puts and the dis­play lay­out can be set with the free con­fig­u­ra­tion soft­ware. The user can also carry out one or two- point hu­mid­ity and tem­per­a­ture ad­just­ment. The tem­per­a­ture probe can also be cal­i­brated sep­a­rately.

OP­TI­MALLY PRO­TECTED ELEC­TRON­ICS

The IP65/NEMA 4 en­clo­sure of­fers op­ti­mal pro­tec­tion for the EE211 elec­tron­ics. Ad­di­tion­ally, for best per­for­mance even in ag­gres­sive en­vi­ron­ment, the mea­sur­ing elec­tron­ics in­side the hu­mid­ity probe are fully en­cap­su­lated.

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