S Y N O P S I SHow familiar are you with your build-

ing’s mechanical equipment room? Theseareas are often “out of sight, out of mind”for building owners and managers. Butoperational and safety guidelines formechanical roomsare spelled out inindustry standardsthat you, as a profes-sional, are liable tocomply with just bybeing aware ofthem. And sincethese standards are commonly used to draft municipal building codes, they may also be the law in your locale.

Today’s mechan-ical room safetystandardsare

embodied in Standard 15-1994 of the American Society of Heating,Refrigeration and Air ConditioningEngineers (ASHRAE). It’s important,therefore, that you be familiar with this

document and how it affects the design,operation and upgrad-ing of your building.

The standard is intentionally writtenin code language so itcan be adopted nearly

verbatim by model code associations —and it can be difficult to understand. This issue of Synopsis provides a basicoverview of mechanical room safety issues in relation to the standard. It is not intended to be a comprehensive

review of all requirements, nor should it be a substitute for reading the doc-

ument itself. It will, however, helpyou to know what to look for

when reading the standardand discussing it with

consulting/specifying engineers and con-

tractors. Also provided are sugges-

tions based on goodpractice installations.

Your Mechanical Room andASHRAE 15-1994: 2001 Update

V O L U M E F O U R N U M B E R O N E( S U P E R S E D E S V O L U M E O N E N U M B E R O N E )

A N H V A C N E W S L E T T E R F O R B U I L D I N G O W N E R S A N D M A N A G E R S

In this issue...• ASHRAE 15-1994

What’s the connection to your mechanical room? . . . . . . . . . . . . 1

• Your LiabilityWhen must you comply with ASHRAE 15-1994? . . . . . . . . . . . . 2

• Check It OutSafety checklist for your mechanical room . . . . . . . . . . . . . 2

• ComplianceWhat steps should you take to comply with ASHRAE 15-1994? . . . 3

• RefrigerantsUnderstanding their properties . . . . . 4

Want to know more about ASHRAE

15-1994: 2001 Update? Visit our

web site at www.carrier.com, click

on Commercial/Industrial Heating

and Cooling Systems and see Newsletter

under Resource Center, download

the publication HVAC Analysis,

Vol. 4, No. 1, written specifically

for consulting engineers.

The standard is intentionally written in code language so it can be

adopted nearly verbatim by modelcode associations — and it can be

difficult to understand.

A Standard For MechanicalRoom Safety

ASHRAE Standard 15 was first issuedas a safety code in 1930, the same yearthat CFC (chlorofluorocarbon) refriger-ants were introduced in the UnitedStates. With increasing refrigerant regulations and phaseouts, as well as thedevelopment of alternative refrigerants,the standard has undergone unusuallyrapid change over the last decade. It was revised in 1992 and again in 1994, followed byseveral addenda inthe late 1990s.

The primarygoal of the standard is to mitigate risks to the environment, to mechanical room operators and, ultimately, to the general public. Since refrigerants have varying degrees of toxicity and flammability, specific procedures and training are needed to use them safely.

ASHRAE 15-1994: YourLiability

Even if your local codes haven’t yet been updated to reflect ASHRAE 15-1994, compliance with the standard can minimize your legal liability bydemonstrating that you have gone to the furthest extent possible to promotemechanical room safety. And, as previ-ously noted, as a building professional or owner, you are considered liable for compliance if you are aware of the

standard. ASHRAE 15 typically applies in several ways.

Mechanical Room Changes

The CFC and HCFC (hydrochlorofl-urocarbons, i.e. R-123, R-22) refrigerantproduction phaseout has raised the critical issue of what to do with existingchillers. There are pros and cons to eachpossible solution — containment, con-version or replacement — and therefore,a thorough evaluation is necessary. It is particularly important to understand

that if the type of refrigerant in achiller is changedor if the chilleritself is replaced,

ASHRAE 15-1994 applies. Section 5.3 of the standard reads: “A change in thetype of refrigerant in a system shall notbe made without the notification of theauthority having jurisdiction, the userand due observance of safety require-ments. The refrigerant being consideredshall be evaluated for suitability.” (Theaddition of containment devices, such ashigh efficiency purges and back-up reliefvalves to your existing equipment, how-ever, does not trigger application of the standard.)

Upgrading a mechanical room to meet the standard typically adds 11 to 13% to the total chiller conversion/replacement project cost, depending on the room’s age and location. This expense should be factored into your refrigerant planning cost analysis.

2

Location of inletvents in relationto exhaust outlets?

Location ofroof drains?

Purgevents tooutside?

Where do the floor drains empty?

Rupture diskoutlet locations?

Is access to mechanicalroom restricted?

Are rubber mats used to cover the drains whennot in use?

Are common headersused only for commonrefrigerant?

Is there a tight seal on doors?

Are safetyrupturelines the right size?

Are there anypit areas in the room?

Are chiller drain valves secure?

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2

3 45

6

7

8

9

FIGURE 1

S Y N O P S I S

Your local building codes may have already been rewritten to reflect

ASHRAE 15-1994.

C H E C K I T O U T

Whether you’re evaluating an existing mechanical room orassessing the situation before acquiring a building, a compre-hensive safety check is a must. Here’s a checklist of some keypotential trouble spots, as illustrated in Figure 1.

1 Are there low areas in the mechanical room?Check the condition of pits or other areas below floorlevel. They may hold chemical residues such as acids,spilled refrigerant, cleaning solvents, etc.

2 Where does the purge vent?A conventional purge (not high efficiency) loses up to 20 pounds of refrigerant for every pound of non-condensible air it removes from the system. All purgesshould vent outside. If high efficiency purges are used,they should be specified per the new ARI (AmericanRefrigeration Institute) Standard 580-2000. Some newhigh efficiency purges have been vented to relief diskpipes. This is not a good practice as refrigerant maycondense to the thin rupture disk resulting in failure due to corrosion.

3 Where are safety rupture disk outlets located?Thin carbon rupture disks are often vented through the roof or side wall. Locations should be at least 15feet above ground level.

4 Could roof drains collect refrigerant? If you loserefrigerant from an exhaust outlet and it vents above aflat, curbed roof, the refrigerant could lay across the roofand find the first exit — probably down the roof drainsand into a sewer system.

5 Are exhaust outlets near inlet vents? Chiller safety relief devices typically vent outdoors, usuallythrough the roof. Check the vent’s proximity to airintakes — they should be at least 20 feet apart.

6 Is access to the mechanical room restricted?These potentially hazardous spaces contain systems critical to a building’s operation. The mechanical roomdoor should have a tight seal to isolate the room in anemergency, as well as prominent signage limiting access to trained personnel only.

7 Where do the floor drains empty? If your chiller and occupied space share the same floor, they may alsoshare a drainage system. Check to see if drains in theoccupied space (i.e., in restrooms) are connected tothose in the mechanical room. Imagine losing a fullcharge and “finding” it in a restroom!

8 Are rupture lines the right size and length?For convenience, safety devices will run into a commonheader if they have common refrigerants. Chillers withdifferent refrigerants should never share common headers. An improperly sized header can exacerbateproblems in an emergency, when the discharge capacityof safetylines is put to the test.

9 Are chiller drain valves secured? These valves are an easy way for an inexperienced technician to get intotrouble. Make sure the valves are locked off.

Mechanical Room Safety Check

Building Code Compliance

Your local building codes may already have been rewritten to reflectASHRAE 15-1994. Many of the majorU.S. building code jurisdictions haveincorporated the standard into theirmodel codes, and state and municipal authorities are following suit.

To find out what’s happening withcodes in your area, meet with your local building inspector. It’s important to be as well informed as possible, especially before making any mechanicalroom changes.

Equipment Design

Manufacturers’ labels reference com-pliance with the standard, so it’s easy tocheck to ensure that anything installed in your building will comply.

Contracts

It’s a good idea to include the specifi-cation that all equipment and service“must be in compliance with the latestASHRAE 15” as standard language for all your installation submittals,

service agreementsand contracts.

Key Steps to Compliance

When examining your mechanicalequipment room for compliance withASHRAE 15-1994, here are some of the primary issues to consider.

Do I Need a Mechanical Room?

The standard lists allowances for all refrigerants in pounds of refrigerantper 1,000 cu. ft. of occupied space (this allowance is calculated for the occupied space in the building and does not apply to the mechanical room).These figures represent the maximumrefrigerant levels allowable for refrigera-tion equipment installed in “occupied”portions of the building. If your systemhas more than the allowable amount of refrigerant, it must be housed in a separate mechanical room.

Purge System and Relief Devices

The standard specifies that all purgesystems (including high efficiency sys-tems) and other relief devices must ventoutside. Even the highest-efficiency

purges lose somerefrigerant. If vented

to the chiller relief piping, refrigerant can

condense, coming into contact with safety rupture disks

and promoting corrosion.

Sizing of Relief and Rupture Devices

ASHRAE 15-1994 specifies theappropriate sizing of pressure reliefdevices. It also includes rating formulasfor discharge capacity of rupture mem-bers and maximum length of dischargepiping. When converting a chiller to a new refrigerant, it is critical to check the size of existing safety devices to be sure they are suitable.

Refrigerant Sensors

All mechanical rooms must have sen-sors capable of detecting refrigerant loss.They should be positioned where vaporfrom a refrigerant leak would most likelyconcentrate, providing early warning so that personnel can prevent dangerousexposure and catastrophic refrigerantloss. The sensors should trigger an alarmand mechanical ventilation, as well asactivate visual and audible alarms insideand outside the mechanical room.

Mechanical Ventilation to the Outdoors

Mechanical rooms must be vented to the outdoors using mechanical ventilation. ASHRAE provides a formula for calculating ventilation capacity requirements.

Access Restrictions

Mechanical rooms must have tight-fitting doors that open and close freely(i.e., no fire doors), and any other open-ing that would permit the passage ofrefrigerant must be sealed. Each entrance

to a refrigerating machineryroom must have a legible permanent sign that reads“Refrigerating MachineryRoom — Authorized

Personnel Only,” and should commu-nicate that when an alarm has beenactivated, entry is forbidden exceptby trained personnel who can address emergencies.

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S Y N O P S I S

4

Refrigerant Storage

Section 11.5 of ASHRAE 15-1994 reads: “The total amount of refrigerant stored in a machineryroom in all containers not providedwith relief valves and piped in accordance with the standard, shouldnot exceed 330 lbs.” This is designedto allow building owners to storeadequate quantities of refrigerant forchiller servicing in separate, approvedstorage tanks. However, you shouldcheck your local building and firecodes for possible exceptions.

Relief Discharge Location

The discharge location of reliefdevices must be at least 20 feet awayfrom any ventilation openings, and not less than 15 feet above ground level (to avoid spraying someone with refrigerant).

Combustion Device Limitation

ASHRAE 15-1994 prohibits the location in a mechanical room of anyopen-flame device using combustion air from inside the room. On theother hand, an open-flame devicesuch as a boiler may be located in amechanical room — if combustionair is drawn from a sealed outsidesource, or the boiler is shut offthrough the use of refrigerant sensor cut outs.

Room Dimensions

The new standard defines anappropriately sized mechanical roomas one that allows access to all equip-ment, including adequate space forservice and maintenance, as well as operation.

Periodic Testing

Ventilation systems and sensorsmust be periodically tested in accordance with the manufacturer’srecommendation and/or local jurisdiction. This is particularlyimportant for refrigerant sensors that are detecting compounds withlow allowable exposure limits.

Many of these sensors require fre-quent calibration. (Higher qualitysensors using infrared technology arepreferred over metal-oxide types, asthey remain close to set calibrations.)

Emergency Planning

The original version of ASHRAE15-1994 mandated the availability of self-contained breathing apparatus(SCBA) for refrigerant leak situations.Addendum “d” to the standard hasremoved this requirement because of the difficulty of implementationfor many commercial buildings.

The addendum mandates anemergency response plan that willallow appropriate measures accordingto the severity of each potentialemergency. Some considerations forthe plan include: types of detectionand alarms; ventilation activation;respiratory protection; evacuation;and, most importantly, a properlytrained response team.

Read ASHRAE 15-1994Clearly, there are many issues

to consider in order to achieve compliance with ASHRAE 15-1994 and its addenda. Your beststrategy is to obtain a copy of thestandard. This issue of Synopsisand consultation with an HVACexpert can help you clarify andunderstand the standard as it applies to your building.

ASHRAE 15-1994 offers manygood, safe solutions, which can andshould become part of your overallstrategic refrigerant planning. A sound plan will help you to meetthe increasingly complex challengessurrounding refrigerant regulation —and maintain a safe environment for your building’s employees and occupants.

LowFlammability

A3Propane

A2R-142b, 152a

B3

B2Ammonia

B1R-123, SO2

A1R-11,12,22,

114,500,134a

HighFlammability

No FlamePropagation

Type ALower Toxicity

Type BHigher Toxicity

ASHRAE 34 Safety GroupFIGURE 2

R E F R I G E R A N T S

Determining which particulars of ASHRAE 15 apply to yoursituation depends in part on the type of refrigerant your airconditioning system uses. Another important document,ASHRAE 34-1992, “Number Designation and SafetyClassification of Refrigerants,” classifies refrigerants in twoways: toxicity and flammability (Figure 2). Generally, the higher the toxicity and flammability, the higher the potentialfor risk and liability.Toxicity

ASHRAE 34 divides refrigerant compounds into twogroups: (A) low-toxicity and (B) high-toxicity. The designa-tion is determined by each compound’s allowable exposurelimit (AEL). Compounds with AELs of more than 400 partsper million (ppm) are classified as type A, while those withAELs of less than 400 ppm are classified as type B. Therefrigerants of the past, such as CFC-11 and HCFC-22 had very high safe exposure limits, as does the alternativerefrigerant HFC-134a. One popular alternative refrigerant,HCFC-123 has a very low allowable exposure limit (30 ppm)and is classed along with ammonia and sulfur dioxide ashigher in toxicity.Flammability

ASHRAE 34 further classifies refrigerants according to their flammability: (1) no flame propagation; (2) low flamma-bility; and (3) high flammability. Ammonia, for example, isconsidered a low-flammability refrigerant, while HCFC-22 and HFC-134a have no flame propagating properties.

Building owners and managers should also be aware that some of the newer alternative refrigerant blends containflammable ingredients. Although their flammability is loweredwhen they are mixed into a blend, flammability may still be an issue in leak situations. When blends leak, the highest-pressure compound exits first. The lowest-pressurecompound is likely to be left in the vessel, and in this statethe mixture may be highly flammable. A recent addendum toASHRAE 34 requires a blend to be classified according to thehighest potential flammability or toxicity of its components.