Heatcraft Refrigeration Products 25000102 operation manual Sight Glass & Moisture Indicator

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Parallel Compressor Systems

Sight Glass & Moisture Indicator

The sight glass/moisture indicator helps determine that a unit has sufficient refrigerant charge and/or when the liquid line filter drier cores need to be replaced.

Bubbles in the glass may indicate a shortage of refrigerant or a restriction in the liquid line (i.e. plugged liquid line filter drier). Moisture typically results from a leak in the refrigerant system or service operations which open the refrigerant system to the atmosphere.

Moisture is detrimental because it leads to the formation of acids which attack components in the system. A change of color in the indicating dial from green to either chartreuse or yellow indicates unacceptable moisture in the system in which case the liquid line filter drier cores need to be changed.

Upon changing the cores, the indicating dial should return to green within 12 hours of returning system to operation.

Figure 10. Sight Glass

Safety Relief Devices

A refrigerant Safety Relief Device is designed to prevent pressure in a Vessel from rising above a safe limit when operating controls fail or when the Vessel is exposed to excessive heat.

When a Vessel, containing liquid refrigerant, is shut off from other parts of the system a rise in temperature will cause a rise in pressure. If the Vessel is completely filled with liquid a small rise in temperature will cause a rapid and excessive rise in pressure due to the expansion of the liquid. If the Vessel contains both liquid and vapor, which is normal for Refrigerant Receivers, the pressure will rise according to the temperature-pressure saturation characteristic of the refrigerant.

If pressure builds up high enough to cause the Vessel to rupture, large quantities of liquid refrigerant are released. This causes a sudden reduction of pressure so that the liquid released is vaporized almost instantly with explosive results.

With a suitable Relief Device installed on the Vessel, the refrigerant is released at a controlled rate and a safe pressure is maintained in the Vessel.

Figure 11. Direct Type Relief Valves

After a“Direct Type”Relief Device has discharged once, it should be replaced. The “Direct Type” Relief Device is designed to re- close automatically at a predetermined pressure, but reliability of the Device to reseal tightly and to operate at the designed pressure can not be guaranteed after discharging. Be safe and replace the Device after such an occurrence.

Figure 12. 3-Way Relief Valve

Parallel Compressor Systems Installation & Operations Manual, October 2004

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Contents Parallel Compressor Systems Table of Contents Model Definition IntroductionInspection Unit DesignationFloor & Foundation Requirements System WarrantyRigging Location Of Equipment Indoor ClearancesUnit Vibration Isolation Location of Equipment OutdoorGround Mounting Roof MountingUnits in Pits Unit AccessVertical Clearance Decorative FencesSuction P-Traps Ventilation Requirements Indoor UnitsElectrical Refrigerant PipingRefrigerant Line Support Refrigerant Line InsulationRef. Line Amount of Expansion Expansion LoopsTable of Values for L 20’ 25’ 30’ 40’ 50’ 75’ 100’ Pressure Loss of Liquid RefrigerantsEquivalent Feet of Pipe Liquid Line Rise in Feet Refrigerant 10’Line 40F 20F Weight of Refrigerants in Copper Lines During OperationSuction Line at Suction Temperature Recommended Line Sizes for R-404A/R-507 100’ 150’ 200’ 25’ Liquid Line SizeExpansion Valve LengthsCapacity 40˚F 20˚F 10˚F Recommended Line Sizes for R-22Suction Line Size 10˚F Liquid Line Size Suction TemperatureTotal Recommended Remote Condenser Line SizesNet 12 & R-134A 502 507 & R-404AStart-up Leak Checking, Evacuation and Start-upEvacuation Priority I Hot Gas Defrost Refrigerant DistributionOff-Cycle Electric DefrostEvaporator Superheat Electronic Control SystemSystem Balancing System SuperheatUnloader Factors CompressorsCopeland Compressors 4D/6D Solid State Modules Typical Voltage RangesCarlyle Compressors Oil Safety SwitchOil Charges Approved Copeland LubricantsRequired Differential Pressure for Unloader Operation Phase Voltage MonitorPart Load Performance Multipliers Sight Glass Safety Relief Devices Sight Glass & Moisture IndicatorDischarge Piping Table Henry Relief Valve Capacity RatingLevel Switch Table Auto Reset ModelsManual Reset Models Liquid Level SwitchOil Separators Module ReplacementOil Control Oil Level Regulators Temprite Valve AdjustmentTemprite Models Sporlan Valve Co Troubleshooting Oil SystemAC&R Model Regulators Liquid Filter-Driers & Suction FiltersReplaceable Suction Filter CompressorMotorBurnoutCleanupProcedureSuction Filter Sporlan Valve CompanyType F Filter Type DF for cleanupType AFD for cleanup Superior Valve CompanyLiquid Drain Control Method Recommended Valve SettingsField Adjustment Hot Gas Bypass Regulator AdjustmentLow Pressure Switch Setting for Rmcc Control SettingsControl Settings for R-404A/R-507 Control Settings for R-22Quarterly General Maintenance ScheduleWeekly MonthlyUnit Short Symptom Cause Remedy CompressorTemperature Does Not RunLow Suction Symptom Cause Remedy LowSwitch Open High SuctionSystem Reference Data Service Record