Manitowoc

Manitowoc Manitowoc

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12.07.2015 Views

ProcedureStep1. Determine the ice machine operating conditions.Example:Air temp. entering condenser: 90°F/32.2°CAir temp. around ice machine: 80°F/26.7°CWater temp. entering water fill valve: 70°F/21.1°C2A. Refer to “Cycle Time” and “Operating Pressure” chartsfor ice machine model being checked. Using operatingconditions from Step 1, determine published freeze cycletime and published freeze cycle suction pressure.Example:Published freeze cycle time: 14.8 - 15.9 minutesPublished freeze cycle suction pressure: 65 - 26 psig2B. Compare the published freeze cycle time andpublished freeze cycle suction pressure. Develop a chart.Example:Published Freeze Cycle Time (minutes)1 2 4 7 10 12 14| | | | | | |65 55 47 39 34 30 26Published Freeze Cycle Suction Pressure (psig)In the example, the proper suction pressure should beapproximately 39 psig at 7 minutes; 30 psig at 12minutes; etc.3. Perform an actual suction pressure check at thebeginning, middle and end of the freeze cycle. Note thetimes at which the readings are taken.Example:Manifold gauges were connected to the example icemachine and suction pressure readings taken asfollows: ________ PSIGBeginning of Freeze cycle: 79 (at 1 min.)Middle of freeze cycle: 48 (at 7 min.)End of freeze cycle: 40 (at 14 min.)4. Compare the actual freeze cycle suction pressure (Step3) to the published freeze cycle time and pressurecomparison (Step 2B). Determine if the suction pressure ishigh, low or acceptable.Example:In this example, the suction pressure is considered highthroughout the freeze cycle. It should have been:Approximately 65 psig (at 1 minute) – not 79Approximately 39 psig (at 7 minutes) – not 48Approximately 26 psig (at 14 minutes) – not 40118 Part Number 80-01111-9 7/10

Suction Pressure High ChecklistImproper Installation• Refer to “Installation and Visual InspectionChecklist” on page 104.Discharge Pressure• Discharge pressure is too high, and is affectingsuction pressure, refer to “Discharge PressureHigh Checklist” on page 150.Improper Refrigerant Charge• Overcharged• Wrong type of refrigerant• Non-condensables in systemOther• Non-Manitowoc components in system• Hot gas valve leaking• TXV flooding (check bulb mounting)• Defective compressorPart Number 80-01111-9 7/10 119

Suction Pressure High ChecklistImproper Installation• Refer to “Installation and Visual InspectionChecklist” on page 104.Discharge Pressure• Discharge pressure is too high, and is affectingsuction pressure, refer to “Discharge PressureHigh Checklist” on page 150.Improper Refrigerant Charge• Overcharged• Wrong type of refrigerant• Non-condensables in systemOther• Non-<strong>Manitowoc</strong> components in system• Hot gas valve leaking• TXV flooding (check bulb mounting)• Defective compressorPart Number 80-01111-9 7/10 119

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