6 EVALUATING REFRIGERANT

PIPING

Introduction This technical procedure applies to the testing and/or inspection of refrig-erant interconnecting piping for facility refrigeration systems. Commercial refrigeration systems require field installation of refrigerant piping to connect major system components such as compressor racks, condensers, and display cases or walk-in coolers. Depending on the facility layout and type of refriger-ation system, refrigerant piping runs can be many hundreds of feet (metres), requiring substantially higher refrigerant charge volumes (typically hundreds of pounds [kilograms]) and significantly more field joints compared to other vapor-compression equipment such as HVAC equipment or self-contained refrigeration equipment. This characteristic tends to increase both the proba-bility of a refrigerant leak and the consequences associated with a refrigerant leak, including greater cost of repair and maintenance and greater

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mental impacts. Furthermore, this characteristic also requires proper system design to ensure that compressor oil returns to the compressor sumps.

Definitions and Abbreviations

Secondary loop refrigeration system: Employing a heat-transfer fluid to cool display cases and coolers that is, in turn, cooled by a refrigerant evapora-tor. The heat-transfer fluid may be single phase (liquid at all points in the loop) or two phase (liquid that evaporates in a heat exchanger in the case or cooler but with minimal pressure drop, i.e., the liquid is not expanded to a two-phase mixture as in a direct expansion [DX] refrigeration system).

Planning and Design Phase

Ensure that the OPR specifies the following:

• Facility layout, especially the locations of refrigerated display cases, walk-in coolers, and machine room

• Inspection requirements, if any, for brazed joints of refrigerant piping

Ensure that the BoD specifies the following:

• The desired refrigeration system type (multiplex, distributed, sec-ondary loop, or other)

• Type of defrost system, consistent with refrigeration system type

• Refrigerant type or types (if system uses a secondary loop)

• Evaluation of design options to minimize refrigerant charge within the constraints specified in the OPR

• Description of refrigerant system design that is consistent with the requirements of Section 4 of ANSI/ASHRAE Standard 147 (2013c);

in case of conflict with the California Green Building Standards Code (CALGreen) (CA 2013a), ASHRAE Standard 147 supersedes Ensure that the CDs specify the following:

• Evaluation of refrigerant pressure drops, showing that pressure drops will be in acceptable ranges

• Piping layout (types, materials, sizes, support, slope, traps, risers, insulation, etc.)

• Accessibility of refrigerant lines for measuring refrigerant tempera-tures and pressures to facilitate commissioning and troubleshooting.

In particular, ensure that the following are specified:

• Method of attachment and insulation of temperature sensors

• Pressure gauge connection (e.g., angle valve) at the condenser

• Receiver size, pumpdown capacity, orientation (vertical or horizon-tal), type (pumpdown or flow through), and trim

• Heat reclaim piping, if heat reclaim is used

• Estimated refrigerant charge

• Estimated oil charge and composition

• Piping insulation requirements

• Refrigerant piping, valves, cases, and receivers that are consistent with the requirements in Section 5.508, Outdoor Air Quality, of CALGreen (CA 2013a), except that the requirements for compliance with the California Mechanical Code (CA 2013b) apply only for installations in California

• Brazing materials, method of brazing, purge requirements, etc., including any industry brazing specifications that must be followed

Refrigeration Commissioning Guide for Commercial and Industrial Systems

(e.g., brazing guidelines from the Copper Development Association or ASTM International)

• Provisions for managing noncondensables Construction and

Installation Phase

Verify that the following are installed as specified in the design docu-ments:

• Refrigerant piping, including type, size, layout/orientation, supports/

clamps/sleeves, valves and fittings, taps for instrumentation, receiv-ers, mounting, and vibration isolators

• Piping insulation

• System for managing noncondensables

Verify that the refrigerant system was installed per the requirements of Section 7.1 of ASHRAE Standard 147 (2013c). In case of conflict with CAL-Green (CA 2013a), ASHRAE Standard 147 supersedes.

Verify that joints have been brazed in accordance with any industry speci-fications listed in the design documents. Inspect brazed joints in refrigerant piping per the requirements of the OPR.

System Start-Up Prior to pressure testing and evacuation, verify the following:

• All refrigerant valves are open so that no part of the refrigeration system is isolated from the rest of the system

• Pressure and vacuum gauges are connected to the appropriate ports on the refrigeration system (not at the vacuum pump)

Verify by observation that the refrigeration system was pressure tested and evacuated per the requirements of Sections 5.508.2.5 and 5.508.2.6 of CALGreen (CA 2013a).

Verify by observation that the refrigerant system was leak tested, evacu-ated, and charged per the requirements of Sections 7.2–7.5 of ASHRAE Stan-dard 147 (2013c). In case of conflict with CALGreen, ASHRAE StanStan-dard 147 supersedes.

After the system is charged with refrigerant and oil, verify that lubricant levels stabilize within 48 h of initiation of system operation.

After all systems are on, refrigerated cases and walk-in boxes have been loaded, and heat reclaim and gas defrost are operational, do the following:

• Compare actual refrigerant charge to that estimated and documented in the BoD and CDs. Provide a document comparison and report the results to the owner and designer.

• Inspect all accessible refrigerant piping to ensure that there are no vibrations that could lead to premature piping failure, especially any that cause metal-to-metal rubbing.

First-Year Operation

Whenever refrigerant or lubricant is added, verify that the date and quan-tity added are documented in a designated log, consistent with the require-ments of Section 8.4.1 of ASHRAE Standard 147 (2013c). Plot trends over time and note any excessive refrigerant charge or lubricant loss.

After one year, do the following:

• Inspect piping runs for signs of corrosion, evidence of leakage (for example, traces of lubricant), and any other abnormalities. Docu-ment in a log the condition of piping and the location/details of any abnormalities.

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• Where refrigerant lines and components are accessible, use a porta-ble refrigerant leak detector to check for leaks. If there is evidence of refrigerant leakage, notify the owner, designer, and/or operator so that they may take corrective actions per Section 8 of ASHRAE Standard 147 (2013c).

• Remove a sample of the refrigeration oil and perform an analysis to ensure its composition is consistent with the design documents or manufacturer’s recommendations.

7 VERIFYING