Emerson Fluid Chiller Guía para resolver problemas descargar pdf (Pagina 42)

Regulators

Emerson Climate Technologies

Fig 4. Cutaway of crankcase pressure

regulator (Emerson OPR)

Fig 5. Cutaway of evaporator pressure regulator

(Emerson EPRB).

Crankcase Regulators

Normally open, the CPR (Fig. 4) closes when com-

pressor pressure rises above the pre-set maximum,

forcing the valve back onto its seat. As suction pressure

drops, the valve starts to reopen, maintaining a balance.

Where to Apply Regulators

EPRs are most commonly used on multiple evapo-

rator systems, installed in the branch lines close to

the required control source. They are used for indirect

temperature control. They also maintain evaporator

pressure during defrost, conserving power, expediting

the defrost and reducing ood back.

CPRs are usually only applied if the system is being

continually “over-pressured,” causing the compressor

to be overloaded. If you suspect that’s the case, check

the amp draw on the compressor while it’s running. If it’s

higher than the plate rating, the system may be a CPR

candidate.

How to Apply Regulators

It isn’t normally necessary to apply both an EPR and

a crankcase regulator. Most installations only utilize an

EPR.

Typical installations of EPRs are in supermarket

systems, large chillers, and industrial processes where

large amounts of heat must be absorbed. Smaller

(including residential) systems of less than 5 tons are

usually equipped with compressors designed to operate

well within 30°-40°F variations.

One of the advantages of suction line regulators in

supermarkets is that by adding EPRs you can control

the operating temperatures of the individual cases in a

single loop system.

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Emerson Fluid Chiller Guía para resolver problemas Pagina 42