Shell Temperature; Minimum Run Time; Shut-Off Sound; Oil Level - Emerson Copeland Scroll ZRH49K Series Application Manuallines

Shell temperature

5.13
The top shell and discharge line can briefly but repeatedly reach temperatures above 177°C if the
compressor cycles on its internal protection devices. This only happens under rare circumstances
and can be caused by the failure of system components such as the condenser or evaporator fan or
loss of charge and depends upon the type of expansion control. Care must be taken to ensure that
wiring or other materials that could be damaged by these temperatures do not come in contact with
the shell.

5.14 Minimum run time

Emerson recommends a maximum of 10 starts per hour. There is no minimum off time because
scroll compressors start unloaded, even if the system has unbalanced pressures. The most critical
consideration is the minimum run time required to return oil to the compressor after start-up. To
establish the minimum run time, obtain a sample compressor equipped with a sight tube (available
from Emerson) and install it in a system with the longest connecting lines that are approved for the
system. The minimum on time becomes the time required for oil lost during compressor start-up to
return to the compressor sump and restore a minimal oil level that will ensure oil pick-up through the
crankshaft. Cycling the compressor for a shorter period than this, for instance to maintain very tight
temperature control, will result in progressive loss of oil and damage to the compressor.

5.15 Shut-off sound

Scroll compressors incorporate a device that minimizes reverse rotation. The residual momentary
reversal of the scrolls at shut off will cause a clicking sound, but it is entirely normal and has no effect
on compressor durability.

5.16 Oil level

The oil level should be maintained at mid-point of the sight glass. If an oil regulator is used the level
should be set within the top half of the sight glass.
The oil level must be carefully monitored during system development, and corrective action should
be taken if the compressor oil level falls below the centre of the sight-glass. The compressor oil level
should be checked with the compressor "off" to avoid the sump turbulence when the compressor is
running.
20 C6.2.7/1007-0619/E