Zf*K5E Compressors For Low Temperature Applications; Zf*K5E Compressors With Liquid Injection; Dtc Valve Specifications; Valve Installation - Emerson Copeland Scroll ZB50KCE Application Manuallines

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ZF*K5E compressors for low temperature applications

ZF*K5E compressors are designed and applicable for both liquid injection and vapour injection
(EVI).
For low temperature applications of ZF*K5E models, liquid or vapour injection is required to keep
discharge gas temperatures within safe limits. The documented application limits (see
Chapter 2.4.3 "Application limits" or the technical data in Select) are based on the ZF* Scroll
compressors equipped with liquid injection or vapour injection.
Injection takes place into two distinct pockets of the spirals without affecting the suction process.
Both types of injection slightly increase the mass flow through the condenser.
All ZF*K5E compressor models are equipped with a 1" – 14 UNS 2A diameter injection port.
4.1

ZF*K5E compressors with liquid injection

Liquid injection is achieved by means of a Discharge Temperature Control (DTC) valve. The same
DTC valve can be used for all ZF*K5E compressors and approved refrigerants. The purpose of
the DTC valve is to eliminate the need for a standard capillary tube.
ZF compressors (BOM 567) include a well in the top cap combined with a valve cap. The DTC
valve is equipped with a custom bulb profile, which must be installed in the top well of the
compressor sensing the temperature closest to the discharge port. The bulb/bellows combination
injects only when cooling is needed and in the required quantity. The DTC valve connections are
1" Rotalock for the compressor injection port and 3/8" braze for the connection to the liquid line.
To prevent a partial or full blockage at the injection port caused by shavings, foreign bodies, etc a
filter should be installed in the liquid line prior to the DTC valve inlet.
Figure 6: DTC valve assembly

4.1.1 DTC valve specifications

Opening setpoint: 121°C ± 3K
Liquid line connection: 3/8"

4.1.2 Valve installation

The valve bulb must be installed in the top cap to adequately control scroll temperatures. The DTC
valve should be tightened on the injection fitting to a torque of 24-27 Nm. It is recommended that
the valve be located perpendicular to the compressor orientation. However it will function properly
in any orientation. The capillary tube connecting the valve to the bulb should be positioned at least
13 mm away from the side of the scroll to avoid contact during operation.
The DTC valve is supplied with a Teflon gasket for the injection port connection and an insulating
cap which is applied to the top of the compressor.
For most efficient thermal sensing, a thin film of thermal grease could be spread around the DTC
valve bulb before installation into the top cap well. However for proper functioning of the valve this
is not absolutely required.
If the additional height from the insulating cap is an issue, the valve cap could be replaced with
high temperature insulation. This should be applied to insulate and protect the valve remote bulb
assembly. This will reduce the total height requirement by 12.7 mm.
C6.2.27/0716-0219/E 9