Refrigeration Safety Standards: ASHRAE 15, EN 378, ANSI/IIAR 2 — EPC Selection Guide

Overview: Three Standards, One Safety Goal

The refrigeration safety standard that applies to your project depends on jurisdiction, refrigerant, and end-use classification. All three primary standards — ASHRAE 15, EN 378, and ANSI/IIAR 2 — address the same underlying goal: safe design, construction, installation, and operation of refrigeration systems. They differ in scope, structure, and jurisdiction.

Choosing the wrong basis early — or leaving it undefined — creates rework at final design review. This guide maps each standard to the decisions EPC procurement and engineering teams need to lock before issuing an RFQ.

The Three Primary Standards

ASHRAE Standard 15

Safety Standard for Refrigeration Systems. Specifies safe design, construction, installation, and operation of refrigeration systems. Used as the basis for refrigeration safety criteria in US model codes, including the IMC (International Mechanical Code). Published by ASHRAE — the American Society of Heating, Refrigerating and Air-Conditioning Engineers. Primary reference for US projects.

EN 378

Refrigerating Systems and Heat Pumps — Safety and Environmental Requirements. Covers design, manufacture, installation, operation, maintenance, repair, and disposal. A four-part standard. Primary reference for EU and UK projects, and commonly referenced for PED-conformant refrigeration equipment. Published by CEN — the European Committee for Standardization.

ANSI/IIAR 2

American National Standard for Safe Design of Closed-Circuit Ammonia Refrigeration Systems. Ammonia-specific design safety standard listed in OSHA’s ammonia refrigeration standards. Referenced alongside ASHRAE 15 for NH₃ systems in US industrial projects. Published by IIAR — the International Institute of Ammonia Refrigeration.

When Each Standard Applies

Match your project jurisdiction and refrigerant to the correct standard basis before issuing an RFQ.

Standard	Jurisdiction / Trigger	Refrigerants Covered	Key Scope Points
ASHRAE 15	US projects; referenced by IMC and many local building codes	All refrigerants; refrigerant classification system (A1–B3)	Machinery room requirements, ventilation, refrigerant detection, safety device setpoints, system classification by refrigerant and charge
EN 378	EU and UK projects; required for PED-conformant refrigeration equipment	All refrigerants; covers HFCs, HFOs, natural refrigerants including NH₃ and CO₂	Design and manufacturing requirements (Part 1–2), installation requirements (Part 3), operation and maintenance (Part 4); environmental limits on refrigerant losses
ANSI/IIAR 2	US projects with ammonia (NH₃) systems; referenced by OSHA PSM/RMP regulations	Ammonia (NH₃) only	Closed-circuit ammonia system design, equipment requirements, machinery room design, pressure relief, detection and alarm, system documentation
ASHRAE 15 + ANSI/IIAR 2	US industrial ammonia refrigeration plants	Ammonia (NH₃)	Both standards apply together; IIAR 2 provides ammonia-specific detail that supplements ASHRAE 15’s general refrigeration safety requirements

What EPC Must Lock Before Issuing an RFQ

Leaving these items undefined transfers scope risk to the vendor and creates redesign loops at final review.

#	Item to Lock	Why It Matters
1	Basis of compliance	ASHRAE 15, EN 378, or both. For ammonia in the US, also confirm ANSI/IIAR 2. This single decision drives machinery room design, ventilation sizing, and safety device selection.
2	Refrigerant selection + site constraints	Refrigerant type and charge affect machinery room classification, ventilation rates, leak detection requirements, and material compatibility. Site constraints affect detector locations and relief valve vent routing.
3	Battery limits	Define what is inside the skid versus by site contractor: refrigerant piping beyond the skid, site ventilation system, refrigerant detection and alarm panel, electrical feed, drains. Unclear battery limits cause the most common redesign requests after IFA issue.
4	Safety devices philosophy	Define the list of required safety devices, setpoint philosophy, alarm vs trip levels, and interlock sequence. Specify which trips are hardwired and which are via PLC. Document what must be proven at FAT vs what is field-verified at SAT.
5	FAT / SAT evidence expectations	Agree what must be proven before shipment (FAT) versus proven on site (SAT). Key FAT items typically include: pressure relief valve documentation, safety device setpoint verification, alarm and interlock functional checks, leak test evidence.
6	Documentation acceptance criteria	Define what “complete data book” means for release-to-ship. Agree the MDR/VDRL format, naming convention, and transmittal rules at kickoff — not when you’re chasing the vendor post-shipment.

The single most expensive sentence in EPC refrigeration procurement is: “We assumed the compliance basis was covered in the spec.”

ASHRAE 15 vs EN 378 — Key Differences for EPC

Both standards target the same safety outcomes. The structural differences affect how you write the RFQ compliance section.

Topic	ASHRAE 15 (US)	EN 378 (EU/UK)
Structure	Single standard covering system safety	Four-part series: design (1), manufacturing (2), installation (3), operation/maintenance (4)
Refrigerant classification	Group A/B (toxicity) + 1/2L/2/3 (flammability); A1 = safest class	Group 1 (low toxicity/flammability) through Group 2 (higher risk); mapped against GWP limits
Scope boundaries	Covers new construction and modifications; referenced by US model building codes	Covers full lifecycle including disposal; PED interface for pressure-bearing components
Machinery room	Requirements based on refrigerant group and charge quantity	Requirements based on refrigerant group, charge quantity, and occupancy classification
Environmental requirements	Limited to safety-related refrigerant release limits	Explicit environmental requirements: GWP considerations, max allowable emissions, end-of-life recovery
Ammonia specifics	Covered; commonly supplemented by ANSI/IIAR 2 for industrial NH₃	Covered within EN 378 framework; no separate ammonia standard required

Evidence Required at Ship Release

These deliverables must be complete and issued — not “in progress” — before the release-to-ship statement is signed.

• Approved battery limits + interface list (mechanical + E&I tie-ins)
• Final P&ID + wiring/termination + I/O list reflecting as-built condition
• Safety device list + setpoint register (all alarms, trips, and interlocks with confirmed setpoints and reset rules)
• Pressure relief valve documentation: set pressure, capacity calculations, installation record, and certificates
• FAT procedure + completed checklist + evidence pack, signed by witness and vendor
• Calibration evidence for instruments tested (traceable certificates with serial numbers)
• Leak test record: test medium, pressure, duration, acceptance criteria, and signed result
• Punch list with closure status (Category A closed before ship; Category B listed with agreed closure plan)
• Vendor Data Book + final document register + release-to-ship statement

• Do not treat “FAT complete” as equivalent to “FAT evidence issued” — put report release as a separate gated milestone
• For EU projects: EN 378 governs system-level safety, while PED 2014/68/EU governs the pressure vessels and heat exchangers within the package. Both frameworks apply and must be confirmed at kickoff.

EN 378 and PED 2014/68/EU — How They Interact

For EU refrigeration packages, two parallel frameworks apply:

EN 378 governs refrigeration system safety — design, manufacture, installation, operation, maintenance, and disposal. It covers the system as a whole, including safety devices, machinery room design, ventilation, and refrigerant leak limits.

PED 2014/68/EU governs pressure-bearing components above 0.5 bar PS — the vessels, heat exchangers, and piping assemblies within the package. Conformity assessment and CE marking requirements apply to these components separately from the system-level EN 378 compliance.

Confirm at kickoff which components require PED conformity assessment and CE marking — and whether a Notified Body is required. Raising this at the final turnover stage is significantly more costly than addressing it at engineering kickoff.

Summary

The compliance basis for a refrigeration package is not a detail to resolve during detailed engineering — it drives machinery room design, ventilation sizing, safety device selection, and the entire documentation framework. Identify the jurisdiction, confirm the standard (ASHRAE 15, EN 378, ANSI/IIAR 2, or a combination), lock the refrigerant and battery limits, and define the evidence expectations before issuing the RFQ. Everything after that is execution against a defined baseline.