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GUIDELINES OF FIELD-CHARGING AIR CONDITIONING SYSTEMS WITH SCROLL
COMPRESSORS
These guidelines are intended for use with Scroll compressors only with R22, R407C, R134a, R404A, R507,
and R410A refrigerants. They do not apply to reciprocating compressors or competitive Scroll compressors.
FIELD-CHARGING – SOME PRECAUTION POINTS
Scroll compressors have a very high volumetric efficiency and quickly pump a deep vacuum if there is
insufficient refrigerant in the system or if refrigerant is added too slowly. Operation with low suction pressure
will quickly lead to very high discharge temperatures. While this process is happening, the scrolls are not
being well lubricated – scrolls depend on the oil mist in the refrigerant for lubrication. A lack of lubrication
leads to high friction between the scroll flanks and tips and generates additional heat. The combination of
heat of compression and heat from increased friction is concentrated in a small localized discharge area
where temperatures can quickly rise to more than 300°C. These extreme temperatures damage the Scroll
spirals and the orbiting Scroll bearing. This damage can occur in less than one minute especially on larger
compressors. Failure may occur in the first few hours or the damage done during field charging may show up
some time later.
Other typical field charging problems include undercharging, overcharging, moisture or air in the system etc.
In time each one of these problems can cause compressor failure.
EQUIPMENT
Minimal equipment is required for field charging. The minimum equipment required to do a satisfactory job
is:-
Set of service gauges
Hoses
Vacuum pump
Vacuum gauge
Scales
Thermometer
CHARGING HOSES
Most field-charging is done using standard service hoses. Hoses are made in different colors with different
working pressures and with different leak rates but the most important point is the presence or absence of
Shredder valve depressors. Shredder valve depressors severely restrict the flow through the service hoses.
This slows evacuation and vapor charging dramatically. In most cases the Shredder depressor can be
removed but it is simpler to have one set of hoses with and one set without Shredder depressors.
Hose with Shredder valve Depressor
Hose without Shredder valve Depressor
Hose selection is important depending whether the system is being evacuated or charged. Charging liquid
from the cylinder into the liquid line should be carried out using an open hose connected to an unrestricted
fitting. This will reduce charging time.
Typical service valves found on the
Shredder Valves
Содержание M4MC075D
Страница 71: ...70 Blower Performance Curves BLOWER PERFORMANCE CURVE MDB 075D...
Страница 72: ...71 BLOWER PERFORMANCE CURVE MDB 100D...
Страница 73: ...72 BLOWER PERFORMANCE CURVE MDB 125D...
Страница 74: ...73 BLOWER PERFORMANCE CURVE MDB 150D...
Страница 75: ...74 BLOWER PERFORMANCE CURVE MDB 200D...
Страница 76: ...75 BLOWER PERFORMANCE CURVE MDB 250D L s 70 65 60...
Страница 77: ...76 BLOWER PERFORMANCE CURVE MDB 300D...
Страница 78: ...77 BLOWER PERFORMANCE CURVE MDB 400D...
Страница 79: ...78 BLOWER PERFORMANCE CURVE MDB 500D...
Страница 80: ...79 BLOWER PERFORMANCE CURVE MDB 075D DR VERY HIGH STATIC...
Страница 81: ...80 BLOWER PERFORMANCE CURVE MDB 100D DR VERY HIGH STATIC...
Страница 82: ...81 BLOWER PERFORMANCE CURVE MDB 125D DR VERY HIGH STATIC...
Страница 83: ...82 BLOWER PERFORMANCE CURVE MDB 150D DR VERY HIGH STATIC...
Страница 89: ...88 MODEL MDB 500D4 DR4 NOTE 1 WITH SEQUENTIAL CONTROLLER 2 VERTICAL AIR DISCHARGE...
Страница 90: ...89 Outlines And Dimensions Outdoor MODEL MMC 075 100D DR MODEL MDB 125D DR...
Страница 91: ...90 MODEL MMC 150D DR OUTDOOR UNIT WITH BALL VALVE MODEL MMC 075D...
Страница 92: ...91 MODEL MMC 100D MODEL MMC 125D...
Страница 93: ...92 MODEL MMC 150D...
Страница 97: ...96 MODEL MDB 400D4 vs MMC 100D x 4 MDB 500D4 vs MMC 125D x 4 WITH SEQUENTIAL CONTROLLER...
Страница 99: ...98 MODEL MDB 125DR vs MMC 125DR WITH U1 125 SLM3 HANDSET MODEL MDB 150DR vs MMC 150DR WITH U1 125 SLM3 HANDSET...
Страница 101: ...100 MODEL MDB 400DR4 vs MMC 100DR x 4 MDB 500DR4 vs MMC 125DR x 4 WITH SEQUENTIAL CONTROLLER...
Страница 102: ...101 Refrigerant Circuit Diagram MODEL MMC 075D 100D 125D 150D...
Страница 103: ...102 MODEL MLC 061C...
Страница 104: ...103 MODEL MMC 075DR 100DR 125DR 150DR R22 M4MC 75DR 100DR 125DR 150DR R407C...
Страница 177: ...2004 McQuay International 1 800 432 1342 www mcquay com ISO 9002 REGISTERED...