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ASHRAE 15: Refrigerating Systems & Machinery Rooms Safety
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1 Refrigerating Systems and Machinery Rooms Applying ASHRAE Standard 15 Advanced HVAC Training ACES-Trane Air Cond Clinics 30 January 2015 K Y Yow Director, Technical Center of Excellence HVAC & Transport , Climate Sector API , Ingersoll Rand 2 refrigerating systems and machinery rooms ANSI/ASHRAE Standards Standard 34-2004: Designation and Safety Classification of Refrigerants Standard 15-2004: Safety Standard for Refrigeration Systems 3 ANSI/ASHRAE Standard 34-2004 Purpose To establish a … “… uniform system for assigning reference numbers and safety classifications to refrigerants.” “… simple means of referring to common refrigerants instead of using the chemical name, formula, or trade name.” Designation and Safety Classification of Refrigerants 4 ANSI/ASHRAE Standard 34-2004 Numbering R-#### carbon-carbon bonds fluorine atoms carbon atoms minus 1 hydrogen atoms plus 1 Designation and Safety Classification of Refrigerants 5 ANSI/ASHRAE Standard 34-2004 Safety Criteria Flammability: 3 classes Toxicity: 2 classes Designation and Safety Classification of Refrigerants 6 ANSI/ASHRAE Standard 34-2004 Flammability Criteria Class 1 No flame propagation Class 2 Lower flammability Class 3 Highly flammable Designation and Safety Classification of Refrigerants 7 ANSI/ASHRAE Standard 34-2004 Toxicity Criteria Class A No known toxicity at < 400 ppm Class B Evidence of toxicity at < 400 ppm … Based on TLV-TWA data or consistent indexes Designation and Safety Classification of Refrigerants 8 ASHRAE Standard 34-2004 Safety Classifications refrigerant safety groups higher flammability A3 B3 lower flammability A2 B2 no flame propagation A1 B1 lower toxicity higher toxicity 9 ANSI/ASHRAE Standard 34-2004 Safety Classifications Refrigerant blends: Rated based on worst-case fractionation … most toxic, most flammable mix Considers response to temperature and pressure changes over time azeotropic blends = consistent zeotropic blends = altered 10 ASHRAE Standard 34-2004 Refrigerant/Blend Data refrig number chemical name or composition (% by weight) compositiondesignating prefix normal boiling point safety group methane series R-11 R-12 R-22 trichlorofluoromethane dichlorodifluoromethane chlorodifluoromethane CFC CFC HCFC 75°F -22°F -41°F A1 A1 A1 CFC HCFC HFC HFC 118°F 81°F -15°F -13°F A1 B1 A1 A2 CFC/HFC HCFC/CFC -27°F –49°F A1 A1 ethane series R-113 R-123 R-134a R-152a 1,1,2–trichlorotrifluoroethane 2,2–dichloro–1,1,1–trifluoroethane 1,1,1,2–tetrafluoroethane 1,1–difluoroethane azeotropes R-500 R-502 R-12/R-152a (73.8/26.2) R-22/R-115 (48.8/51.2) 11 ANSI/ASHRAE Standard 15-2004 Purpose and Scope “… specifies the safe design, construction, installation, and operation of refrigeration systems” “… establishes safeguards for life, limb, health, and property and prescribes safety requirements” Safety Standard for Refrigeration Systems 12 ANSI/ASHRAE Standard 15-2004 Applicability New construction: “ … the design, construction, test, installation, operation and inspection of mechanical and absorption refrigeration systems, including heat pumps systems used in stationary applications” Safety Standard for Refrigeration Systems 13 ANSI/ASHRAE Standard 15-2004 Applicability Certain replacements: “… modifications including replacement of parts or components if they are not identical in function and capacity …” Safety Standard for Refrigeration Systems 14 ANSI/ASHRAE Standard 15-2004 Applicability Certain conversions: “… and to substitutions of refrigerant having a different designation” Safety Standard for Refrigeration Systems 15 ANSI/ASHRAE Standard 15-2004 Enforceability standard of care model code “influential” state law “enforceable” 16 ANSI/ASHRAE Standard 15-2004 Classification Criteria Refrigerant safety Allowable tolerance for human exposure Building occupancy Speed of evacuation Refrigerating system Probability of occupant exposure Safety Standard for Refrigeration Systems 17 ANSI/ASHRAE Standard 15-2004 Refrigerant Safety refrigerant safety groups (ANSI/ASHRAE Standard 34-2004) higher flammability A3 B3 lower flammability A2 B2 no flame propagation A1 B1 lower toxicity higher toxicity our focus 18 ASHRAE Standard 15-2004 Building Occupancy Institutional Occupant impairment prevents quick exit Public assembly Large congregation congests exits Residential Individual and multi-unit living facilities Industrial Restricted access to specific areas 19 ANSI/ASHRAE Standard 15-2004 Building Occupancy Commercial Where people transact business, receive personal services, or purchase food/goods Large mercantile Where > 100 people congregate to purchase personal merchandise Mixed Two or more occupancy types within the same building 20 ANSI/ASHRAE Standard 15-2004 Refrigerating System SYSTEM TYPE cooling or heating source material to be cooled/heated SYSTEM CLASSIFICATION direct high probability indirect open spray high probability (conditional) double indirect open spray low probability indirect closed low probability indirect vented closed low probability 21 ANSI/ASHRAE Standard 15-2004 Refrigerant Quantity Limits High-probability systems: Concentrations must not exceed Table 1 values (Section 7.2) Maximum quantity based on volume of occupied space (Section 7.3) Special considerations for institutional and industrial occupancies (Sections 7.2.1, 7.2.2) Safety Standard for Refrigeration Systems 22 ANSI/ASHRAE Standard 15-2004 Occupied Volume Nonconnecting spaces (Section 7.3.1) Refrigeration system in occupied space No permanent openings, no HVAC duct Use volume of smallest occupied space Limit height to 8.2 ft for spaces on different levels Safety Standard for Refrigeration Systems 23 ANSI/ASHRAE Standard 15-2004 Occupied Volume Ventilated spaces (Section 7.3.2) Refrigeration system in air handler Omit spaces that can be isolated from leak source Excludes smoke dampers, shutoff (<10%) VAV boxes Use smallest occupied space Include plenums and ductwork Safety Standard for Refrigeration Systems 24 ANSI/ASHRAE Standard 15-2004 Occupied Volume Summary: Occupied volume calculation depends on application Determines worst-case dilution scenario … Smallest occupied-space volume Largest refrigerant quantity in a single circuit/unit Assumes that refrigerant disperses equally throughout air in occupied space Safety Standard for Refrigeration Systems 25 ANSI/ASHRAE Standard 15-2004 Refrigerant Quantity Limits refrigerant qty per occupied space common name chemical name or composition (% by weight) safety group lb per Mft³ ppm by vol A1 A1 A1 1.6 12.0 9.4 4,000 40,000 42,000 A1 B1 A1 A2 1.9 0.4 16.0 1.2 4,000 1,000 60,000 7,000 A1 A1 12.0 19.0 47,000 65,000 methane series R-11 R-12 R-22 trichlorofluoromethane dichlorodifluoromethane chlorodifluoromethane ethane series R-113 R-123 R-134a R-152a 1,1,2–trichlorotrifluoroethane 2,2–dichloro–1,1,1–trifluoroethane 1,1,1,2–tetrafluoroethane 1,1–difluoroethane azeotropes R-500 R-502 R-12/R-152a (73.8/26.2) R-22/R-115 (48.8/51.2) 26 ANSI/ASHRAE Standard 15-2004 Equipment Location Place all refrigeration components in a “machinery room” or outdoors IF: Refrigerant quantity exceeds Table 1 Direct-fired absorption is used Safety Standard for Refrigeration Systems 27 ANSI/ASHRAE Standard 15-2004 Equipment Location Machinery room: “… a space, meeting the requirements of 8.11 or 8.12, that is designed to house compressors and pressure vessels” (Section 3) 28 Equipment Location Aliases: Signifies compliance with Standard 15 Equipment room Mechanical room Mechanical equipment room (MER) Refrigeration room Machinery room 29 ANSI/ASHRAE Standard 15-2004 Equipment Location Refrigerant class determines machinery room requirements: For nonflammable refrigerants (A1 or B1), conform to Section 8.11 For flammable refrigerants (A2, B2, A3 or B3), conform to Sections 8.11 and 8.12 Safety Standard for Refrigeration Systems 30 ANSI/ASHRAE Standard 15-2004 Summary of Restrictions Place chillers in machinery rooms Conform with Section 8.11 when machinery room houses A1 or B1 refrigerants Safety Standard for Refrigeration Systems 31 section 8.11 requirements for Machinery-Room Design Ventilation Refrigerating system placement Doors, passageways, access Refrigerant monitoring Open-flame devices Pressure-relief piping General 32 machinery-room design requirements Ventilation Natural (gravity-driven) Minimum cross-section of opening Opening location Mechanical (powered) ventilation Normal rate for human occupancy Alarm rate if a leak is detected 33 machinery-room design requirements Natural Ventilation Permissible if: occupied building occupied building > 20 ft refrigerating system lean-to or other ventilated structure 34 machinery-room design requirements Natural Ventilation Minimum free-aperture cross section for ventilation opening: F = G0.5 where: F = free opening area, ft² G = mass of refrigerant, lb 35 machinery-room design requirements Mechanical Ventilation Normal rate: Provide minimum ventilation during occupancy: 0.5 cfm/ft² or 20 cfm/person Maintain comfort by not exceeding the higher of: inlet air + 18°F or 122°F room air (maximum) 36 machinery-room design requirements Mechanical Ventilation Alarm rate: Exhaust accumulated refrigerant resulting from a leak or rupture Q = 100 × G0.5 where: Q = airflow (ft³/min) G = mass of refrigerant (lb) 37 machinery-room design requirements Mechanical Ventilation Vent to outdoors Cause no nuisance or danger Provide for makeup air Position to avoid recirculation Provide separate supply/return ducts Use multiple or multispeed fans to obtain reduced airflow for normal ventilation 38 Suggested Exhaust-Fan Location exhaust fan breathing zone: 5 ft 39 end view exhaust airflow plan view ventilation airflow Dual-Purpose Mechanical Ventilation 40 section 8.11 requirements for Machinery-Room Design Ventilation Refrigerating system (chiller) placement Doors, passageways, access Refrigerant monitoring Open-flame devices Pressure-relief piping General 41 machinery-room design requirements Chiller Placement Provide unobstructed space for service, maintenance, inspection, and operation Comply with applicable safety standards and requirements of presiding regulatory agency If mounted overhead, provide ≥ 7.25 ft of clear head room below 42 machinery-room design suggestions Multiple-Chiller Layouts chillers air inlets arrangement A IDEAL exhaust fans arrangement B ADEQUATE 43 section 8.11 requirements for Machinery-Room Design Ventilation Refrigerating system (chiller) placement Doors, passageways, access Refrigerant monitoring Open-flame devices Pressure-relief piping General 44 machinery-room design requirements Doors, Passages, Access Limit entry to authorized personnel Provide adequate number and type of doors Prevent openings to other parts of building No “shared” air-handling systems No open raceways or tunnels 45 section 8.11 requirements for Machinery-Room Design Ventilation Refrigerating system (chiller) placement Doors, passageways, access Refrigerant monitoring Open-flame devices Pressure-relief piping General 46 machinery-room design requirements Refrigerant Monitoring Select a “detector” that activates at or below TLV®–TWA Broadcasts an alarm Initiates mechanical ventilation Place sensor where refrigerant will concentrate 47 machinery-room design requirements Refrigerant Monitoring 2004 standard alarm requirements Audible and visual signals Alarms inside machinery room and outside each entry Advisory signage at each entry Manual reset inside machinery room … and permits additional alarm levels (if TLV-TWA actions are met) 48 machinery-room design suggestions Refrigerant Monitoring Position sensor 12-18 inches above floor Arrange sensor site based on ventilation Continuous: Between chiller and exhaust fan exhaust fan sensor chiller Intermittent: Between entry and chiller (within 50 ft) exhaust fan sensor chiller 49 machinery-room design suggestions Refrigerant Monitoring roof or floor occupied space machinery room refrigerant monitor 5 ft sample-in tubing particle filter 12–18 in. chiller 50 Suggested Sensor Placement for Intermittent Ventilation sensor chillers sensor 51 Multichannel Scanner for Multiple Chillers and/or Floor Levels sensor monitor/ multichannel scanner pit 52 section 8.11 requirements for Machinery-Room Design Ventilation Refrigerating system (chiller) placement Doors, passageways, access Refrigerant monitoring Open-flame devices Pressure-relief piping General 53 machinery-room design requirements Open-Flame Devices “No open flames that use combustion air from the machinery room shall be installed where any refrigerant is used.” Exceptions: Sealed duct brings air into combustion chamber, preventing leaked refrigerant from entering Refrigerant detector automatically shuts down combustion if a refrigerant leak occurs 54 section 8.11 requirements for Machinery-Room Design Ventilation Refrigerating system (chiller) placement Doors, passageways, access Refrigerant monitoring Open-flame devices Pressure-relief piping General 55 machinery-room design requirements Pressure-Relief Piping Route vent-line piping to discharge outdoors Position vent-line discharge: ≥ 15 ft above grade level ≥ 20 ft from any building opening 56 roof Refrigerant Vent-Line purge-discharge vented to atmosphere relief device (alternate arrangement) exterior wall Prevent discharge from contacting personnel 15 ft above ground level, 20 ft from building openings 57 machinery-room design requirements Pressure-Relief Piping Ensure that relief-line size exceeds outlet diameter of relief device Use Appendix H equations to determine maximum vent-line run If manifolding multiple relief devices: Consider effect of back pressure Ensure that manifold area exceeds sum of relief-device areas 58 section 8.11 requirements for Machinery-Room Design Ventilation Refrigerating system (chiller) placement Doors, passageways, access Refrigerant monitoring Open-flame devices Pressure-relief piping General 59 machinery-room design requirements General Changing refrigerants: Obtain owner’s permission Notify presiding authority Update/add appropriate signage Storing refrigerant in machinery room: Limit to 330 lbs in approved storage containers Comply with Section 9.7 to store more 60 machinery-room design requirements General Signage: Identify installer, refrigerant, lubricant, field test pressure Identify controls, switches, and piping Limit access to authorized personnel Prevent access during alarm (except with protective gear and proper training) 61 machinery-room design requirements General Emergency shutdown procedure: Post conspicuously where convenient to operators Include service contact information Provide instructions and contacts for reportable incidents Forbid entry if refrigerant alarm (per 8.11.2.1) activates 62 machinery-room design requirements General Self-contained breathing apparatus (SCBA): Locate manual reset for alarm inside machinery room Provide signage forbidding entry without an SCBA during an alarm condition Review Appendix I, “Emergencies in Refrigerating Machinery Rooms,” for further guidance 63 machinery-room design requirements Summary Ascertain need for a machinery room Building occupancy Refrigerant safety Refrigerating system Machinery room requirements Same for all quantities of A1 and B1 refrigerants Primary goal: SAFETY 64 Refrigerating Systems and Machinery Rooms Applying ASHRAE Standard 15 Questions?
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