Emerson Fluid Chiller Guide de dépannage télécharger pdf (Page 32)

System Protectors

Emerson Climate Technologies

Compacted bead style lter drier, Emerson’s EK-Plus

Absorption vs. Adsorption

One factor to consider in selection is ab- vs. ad-

sorption. Absorption means a material’s ability to take

another substance into its inner molecular structure.

An adsorbed substance doesn’t penetrate the mo-

lecular structure. It simply starts building up on the sur-

face of the adsorbent. Walls, cracks, crevices are part of

the surface area and are able to hold other substances,

greatly increasing capacity.

Modern desiccants are extremely porous and have

a large surface area and internal pore volume of a size

and shape to adsorb and retain water molecules.

Types of Filter driers

All the liquid line lter driers on the market today are

a variation of one of two types: the molded core type or

the bead type.

Molded core type lter driers are manufactured by

mixing desiccants (which remove the soluble contami-

nants) with a bonding agent, then baking them to give

them permanent shape and to activate the drying ingre-

dients. The result is a porous core which acts as lter

and drying agent.

Compacted bead style lter driers are manufactured

with the active desiccant in bead or pellet form; no bond-

ing material is used. Rather, compacting comes from

mechanical pressure exerted by a spring. Compacted

bead-style lter driers usually include an additional lter

network to trap solid contaminants from the refrigerant,

unlike most core styles.

The separate and distinctive lter media can take

various forms that permit depth ltration with greater

solid contaminant capacity and contaminant retention

during start-up and shut- down when turbulent condi-

tions exist.

Compacted bead lter driers offer the maximum

volume of desiccant because ltering and drying is done

in one mass. But, because a molded core is porous,

it does not hold all solid contaminants; often particles

are washed through channels within in the core when

pressures surge. Better holding power is possible with

a more compacted core. But pressure drops increase

inversely.

Fig 1. Proper placement of lter drier in the system

Dirt, Waxes, Acid

Every system has contaminants in it as soon as it is

opened. These contaminants may be insoluble, such as

metal lings not removed in manufacturing, or airborne

dirt that entered when the system was opened. Or they

may be soluble, such as waxes, acids, water and resins

that develop through reactions between air, the refriger-

ant, or lubricant.

Any of these can cause system failure. Installing an

all-purpose lter drier can lessen chances for trouble.

There are basic differences to consider: type of lter,

how it lters, and its true capacity.

Most manufacturers rate their lters to ARI Standard

710. But even though two clean lter driers may be rated

the same, there can be a vast difference in ow as the

quantity of solids picked up increases.

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Emerson Fluid Chiller Guide de dépannage Page 32

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