Refrigeration System Equipment Room Design

Refrigeration System Equipment Room Design
This presentation is intended to promote the refrigeration equipment room design practices described in ASHRAE Std 15. Where appropriate I have listed the pertinent sections of the Standard at the bottom of the notes page for reference. The Trane Company La Crosse, Wisconsin

ANSI/ASHRAE Standards
“Number Designation And Safety Classification Of Refrigerants” Standard … “Safety Code For Mechanical Refrigeration” The primary focus of this presentation is ASHRAE Std 15, however, Std 15 relies on some information provided by ASHRAE Std 34. The first few slides cover the portion of Std 34 that are applicable to Mechanical Equipment Room Design.

ANSI/ASHRAE Standards … Standard 34-1992
Purpose? To establish a … “… simple means of referring to common refrigerants instead of using the chemical name, formula, or trade name.” “… uniform system for assigning reference numbers and safety classifications to refrigerants.” Standard 34 has a two fold purpose. It establishes proper names and numbers for refrigerants. Using the proper names for refrigerants prevents the confusion caused by using brand names (such as Freon), or the complication of using the chemical name or formula. A numbering scheme is used to provide the numbers we commonly refer to refrigerants by, such as 11, 22, 123, etc. Numbering is based on the number of fluorine, hydrogen, carbon, bromine, chlorine atoms and, carbon-carbon bonds. The second function of Std 34 is to provide the safety designations for refrigerants. Sections 4 and 5 “Number Designation And Safety Classification Of Refrigerants”

ASHRAE Standard 34-1992 … Refrigerant Safety Classifications
Group A3 Group A2 Group A1 Group B3 Group B2 Group B1 higher flammability lower flammability no flame propagation lower toxicity higher toxicity Safety designation is based on two criteria, flammability and toxicity. There are three levels of flammability (no flame propagation, lower and higher) and two levels of toxicity (lower and higher). Most of the refrigerants that were used in the past were A1 refrigerants. These had no flame propagation and were in the lower toxicity category. As new refrigerants are examined for use in refrigeration cycles these refrigerants may fall in other safety classification categories. For reference, the refrigerant ammonia is classified in group B2. It is in the higher toxicity category and the lower flammability category. Seciton 6

ASHRAE Standard 34-1992 … Refrigerant/Blend Data
Refrigerant Chemical Name Or Composition (% By Weight) Methane Series CFC (or R) –11 Trichlorofluoromethane 75°F A ,000 CFC (or R) –12 Dichlorodifluoromethane –22°F A ,000 HCFC (or R) –22 Chlorodifluoromethane –41°F A ,000 Ethane Series CFC (or R) –113 1,1,2–Trichlorotrifluoroethane 118°F A ,000 HCFC (or R) –123 2,2–Dichloro–1,1,1–Trifluoroethane 81°F B ,000 HFC (or R) –134a 1,1,1,2–Tetrafluoroethane –15°F A ,000 HFC (or R) –152a 1,1–Difluoroethane –13°F A ,000 Azeotropes R–500 R–12 (73.8) / R–152a (26.2) –27°F A ,000 R–502 R–22 (48.8) / R–115 (51.2) –49°F A ,000 Normal Boiling Point Safety Group Lbs/ 1000 cu ft PPM By Vol Refrig Qty Per Occupied Space For some of the more commonly used refrigerants this Table shows the chemical name, proper number and chemical abbreviation, and the safety category. As an example, Trichlorofluromethane is given the common name CFC 11 (R 11 is also an acceptable common name), and is in the A1 safety group. We will revisit this Table and explain the rest of the information later in the presentation. This is the last slide on Standard 34. We now turn our attention to Standard 15 for the remainder of the presentation. See Table 1 in Standard 34.

Purpose? “… to specify safe design, construction, installation, and operation of refrigerating systems.” Scope? “This code established safeguards for life, limb, health, and property and prescribes safety standards.” Read over the purpose and scope for Standard 15 and note the focus on safety. In fact, the name of the standard is the “Safety Code for Mechanical Refrigeration.” Keep this focus on safety in mind as you read the details of the Standard. Whenever you have difficulty interpreting the intent of a particular section remember that the intent of the Standard to is to promote the safe use of refrigeration systems. Sections 1 and 2.1 “Safety Code For Mechanical Refrigeration”

It applies to … “ … mechanical refrigerating systems and heat pumps used in the occupancies defined in Section 4 and installed subsequently to adoption of this code” There are three major cases when the Standard applies. The first is new construction. Anytime a refrigeration system is installed in a new building the design must follow ASHRAE 15. The use of the word “code” in this part of the Standard is not entirely correct. An ASHRAE Standard is written by a committee of ASHRAE and is reviewed by the membership before it is published. As an ASHRAE Standard it has no enforcement. Typically the Standard is then picked up by a one of the model code adjacencies such as Southern Building Code, Building Officials and Code Administrators (BOCA) or the International Conference of Building Officials (ICBO). It is incorporated into a model code which can be adopted by the states. For these codes to be enforceable they must be voted on by the state legislature. At that point they are the code that code officials enforce when they approve a building. The other way that ASHRAE Standards are used is by the courts in the case of a lawsuit. In this case the court looks to the ASHRAE Standard that was current at the time of design to establish the standard of care for proper design. Section 2.2 “Safety Code For Mechanical Refrigeration”

It also applies to … “… parts or components added after adoption of this code, or a change to a refrigerant of a different number designation after adoption of this code” This portion requires an existing MER to be updated to meet the code when a refrigerant conversion is performed. Or if when a new chiller is added or when an existing system is modified by adding a new component that does not replace a similar component. Section 2.2 “Safety Code For Mechanical Refrigeration”

Finally, it applies to … “… parts or components replaced after adoption of this code only if they are not identical in function” This final portion requires the upgrade when a part is replaced that doesn’t have the same function as the original part. It’s a little difficult to think of a case where this applies. It doesn’t apply if a purge unit is replaced with a newer more efficient model. In this case they both have the same function and therefor the room does not need to be upgraded. Now that we know when we need to apply the Standard, let’s look at how to apply it. Section 2.2 “Safety Code For Mechanical Refrigeration”

Provides classification criteria for … Safety group Occupancy type Refrigerating system “probability” It is important to realize that Standard 15 applies to all refrigeration equipment from window air conditioners and ice machines up to large chillers containing several thousand pounds of refrigerant. This presentation focuses on those systems that require a Machinery Room. Obviously different requirements apply to different types and applications of refrigeration equipment. The Standard uses these three criteria (or classifications) to determine the requirements for any piece of refrigeration equipment. “Safety Code For Mechanical Refrigeration”

Provides classification criteria for … Safety group Occupancy type Refrigerating system “probability” The first criteria, Safety Group, is based on the type of refrigerant. “Safety Code For Mechanical Refrigeration”

ASHRAE Standard 15-1994 … Safety Group Classification
Standard 34’s refrigerant safety classifications Group A3 Group A2 Group A1 Group B3 Group B2 Group B1 higher flammability lower flammability no flame propagation lower toxicity higher toxicity ASHRAE Standard 34 gives the Safety Group designation. For this presentation we focus on Groups A1 and B1. Section 6

Provides classification criteria for … Safety group Occupancy type Refrigerating system “probability” For the purposes of Std 15, ASHRAE divides occupancies into seven categories as follows. “Safety Code For Mechanical Refrigeration”

ASHRAE Standard 15-1994 … Occupancy Classification
Institutional Occupants can’t readily leave without help Public assembly Where large numbers of occupants can’t vacate quickly Residential Occupants have complete, independent living facilities Industrial Occupancy is restricted only to authorized personnel The categories are divided according to how easily the occupants of the building could respond to a release of refrigerant. Institutional occupancy includes hospitals and jails. In this occupancy type the occupants would have difficulty evacuating the building. Industrial occupancy is at the other end of the spectrum. This occupancy type prohibits access by the general public and requires that the occupants are authorized personnel. Section 4

ASHRAE Standard 15-1994 … Occupancy Classification
Commercial Occupants transact business, receive personal services, or purchase food or other goods Large mercantile Premises where more than 100 people congregate to purchase personal merchandise Mixed Two or more occupancies share the same building The seventh category “Mixed” is used when the building contains more than one occupancy type. A good example of this is a hotel which has a residential occupancy, and, if it has a restaurant, a commercial occupancy. The walk-in cooler portion of the restaurant may even be considered industrial occupancy. When the different occupancy areas are separated by tight fitting walls floors, ceilings, self closing doors and use separate HVAC systems the occupancies can be considered separately. If the isolation described above does not exist between occupancies then the occupancy with the most stringent requirements governs the entire area. Section 4

Provides classification criteria for … Safety group Occupancy type Refrigerating system “probability” The final classification is refrigerating system probability. This the probability that refrigerant discharged from the refrigeration equipment would reach the occupants of the building. There are 5 system categories as shown on the next slide. Section 5 “Safety Code For Mechanical Refrigeration”

ASHRAE Standard 15-1994 … Refrigerating System Probability
System Designation Cooling Or Heating Source Air Or Substance To Be Cooled, Heated High Probability Direct Indirect Open Spray The system types range from Direct to Indirect Vented Closed. There is a high probability that refrigerant from a leak will reach the occupants in direct systems such as rooftops and split systems where the refrigerant coil is in the air stream. On the other hand there is a low probability that refrigerant will reach the occupants in an Indirect closed system such as a water chiller because a secondary fluid (water) is used in the coil. Indirect Open spray systems, also known as air washers, are considered low probability systems as long as the water pressure is greater than the refrigerant pressure, at all times, operating and standby. If this requirement is not met air washers must be considered high probability systems. Section 5. Specifically and 5.2.2 Double Indirect Open Spray Low Probability Indirect Closed Indirect Vented Closed

ASHRAE Standard 15-1994… Refrigerant Quantity Rules
Public Assembly, Refrigerant System Residential, Commercial, Group Probability Institutional Large Mercantile Industrial A1 High Low 4 4 4 A2 High Low 7 7 7 A3 High Low 9 9 7 B1 High 2, 6 1, Low 4 4 4 B2 High 5, 6 5, Low 7 7 7 B3 High Low 9 9 7 Applicable Rules By Occupancy Classification Once the 3 classifications are defined this matrix is used to determine which “rule” applies. The focus of this presentation is Low Probability Systems (Chillers) with either A1 or B1 refrigerants in all occupancy types. If we highlight these selections …. Table 2

ASHRAE Standard 15-1994 … Refrigerant Quantity Rules
Public Assembly, Refrigerant System Residential, Commercial, Group Probability Institutional Large Mercantile Industrial A1 High Low 4 4 4 A2 High Low 7 7 7 A3 High Low 9 9 7 B1 High 2, 6 1, Low 4 4 4 B2 High 5, 6 5, Low 7 7 7 B3 High Low 9 9 7 Applicable Rules By Occupancy Classification We see that Rule 4 applies in all cases. From the list of rules we see that Rule 4 says …..

ASHRAE Standard 15-1994 … Refrigerant Quantity Rules
“When the quantity of refrigerant in any system exceeds Table 1 amounts, all refrigerant-containing parts, except piping and those parts outside the building, shall be installed in a machinery room constructed in accordance with the provisions of 8.13.” When the quantity of refrigerant in any system exceeds Table 1 amounts, all refrigerant-containing parts, except piping and those parts outside the building, shall be installed in a machinery room constructed in accordance with the provisions of 8.13. The quantity referred to is the quantity of refrigerant in the largest chiller or largest circuit. In short, it is the most refrigerant that can be released from a single event. Section 8.13 provides the design requirements for systems that exceed the quantities shown in Table 1. Section rule 4.

ASHRAE Standard 34-1992 … Refrigerant Safety Classifications
Refrigerant Chemical Name Or Composition (% By Weight) Methane Series CFC (or R) –11 Trichlorofluoromethane 75°F A ,000 CFC (or R) –12 Dichlorodifluoromethane –22°F A ,000 HCFC (or R) –22 Chlorodifluoromethane –41°F A ,000 Ethane Series CFC (or R) –113 1,1,2–Trichlorotrifluoroethane 118°F A ,000 HCFC (or R) –123 2,2–Dichloro–1,1,1–Trifluoroethane 81°F B ,000 HFC (or R) –134a 1,1,1,2–Tetrafluoroethane –15°F A ,000 HFC (or R) –152a 1,1–Difluoroethane –13°F A ,000 Azeotropes R–500 R–12 (73.8) / R–152a (26.2) –27°F A ,000 R–502 R–22 (48.8) / R–115 (51.2) –49°F A ,000 Normal Boiling Point Safety Group lbs/ 1000 cu ft PPM By Vol Refrig Qty Per Occupied Space This slide shows the Table 1 amounts for the most common refrigerants. The quantity referred to in Rule 4 is the Refrigerant Quantity Per Occupied Space shown on the right hand side of the chart. For a chiller in a mechanical equipment (MER) room the occupied space volume is the volume of the MER. The refrigerant quantity is the pounds of refrigerant in the largest chiller or circuit. Again this is the most refrigerant that can be released from a single event. Per rule 4 if the Table 1 quantity is exceeded the room where the chiller is installed must be made into a Machinery Room as described in Section Nearly all large water chillers are required to be installed in a Machinery Room. In those rare cases where a chiller is installed in a very large room (perhaps an industrial facility) and the Table 1 values are not exceeded it is still recommended that at least a monitor and probably local ventilation should be installed. Table 1 values are based on the assumption that the refrigerant is equally dispersed into the entire room volume. While this is a good assumption for window air-conditioner it is not for a large chiller with several hundred pounds of refrigerant. The remainder of this presentation describes the requirements outlined in Section At this point it should be noted that the requirements of are the same for all refrigerants. See Table 1 in the Standard.

Equipment Room Design Ventilation Refrigeration system placement
Doors, passageways and access Refrigerant monitoring Open-flame devices Pressure-relief piping General requirements This slide lists the major requirements listed by Section We will cover each of these starting with Ventilation.

Doors, passageways and access Refrigerant monitoring Open-flame devices Pressure-relief piping General requirements The first topic covered is the ventilation requirements of the Machinery room. This slide could probably go away.

equipment room design … Ventilation
Volume requirements for … Natural ventilation Mechanical ventilation Normal rate Alarm rate The ventilation requirements are divided into two major categories, Natural and Mechanical. This is an either/or choice. Mechanical is used most often as Natural essentially requires the chillers to be sheltered but open to the outdoors. Mechanical is further divided into Normal and Alarm rates, both of which apply when mechanical ventilation is used. Section

Remote machinery room … Occupied Building Occupied Building More Than 20 Feet Natural Ventilation can be used when the refrigeration system is sheltered by a penthouse or lean-to that is open to the outdoors and is separated from occupied buildings or building openings by more than 20 feet. Section Refrigeration System Lean-to Or Other Structure With Natural Ventilation

Natural ventilation For refrigerating systems installed “outdoors, more than 20 ft from [any] building openings …” When Natural Ventilation can be used the Standard calls for a minimum amount of free open area to allow natural draft to ventilate the Machinery Room. The amount of free open area required (F) is given by the equation shown above where G is the pounds of refrigerant in the largest chiller or largest circuit whichever is greater. As with the calculation for Table 1 it is the most refrigerant that could be lost by a single release. In most cases the wintertime outdoor conditions will prohibit the use of Natural Ventilation. Note: G to the 0.5 power is the square root of G. Section F = G0.5 where: F = free opening area (sq ft) G = mass of refrigerant (lbs)

Normal-rate mechanical ventilation Needed whenever the equipment room’s occupied Requirements: 0.5 cfm per sq ft OR 20 cfm per person Must operate, if necessary for operator comfort, at a volume that limits the temperature rise (T) to no more than 18°F Mechanical Ventilation, which is required in most Machinery rooms, has two rates. The first, Normal-Rate Ventilation, is required whenever the Machinery room is occupied. The rate is 0.5 cfm per sq ft of Machinery room area or 20 cfm per person. In most cases designers use the 0.5 cfm per sq ft rate as the occupancy level of a Machinery room is difficult to predict. In most cases this level is sufficient to meet the requirement that the room temperature not exceed the ambient by more than 18 degrees. If the room has a lot of heat sources, such as large air cooled motors, it may be necessary to increase the rate to meet this secondary requirement. While the Standard states that the room must be ventilated at this rate whenever it is occupied it leaves “how” part up to the designer. Several options exist including continuous fan operation, trigger the fan by an occupancy sensor or simply place a sign by a switch that controls the fan stating, “This fan must be operated whenever the room is occupied.” Section

Alarm-rate mechanical ventilation Required to exhaust accumulated refrigerant Q = 100 × G0.5 The second rate covered under Mechanical Ventilation is the Alarm-rate. The Alarm-rate airflow quantity (Q) is prescribed by the formula shown where G is the pounds of refrigerant in the largest chiller or largest circuit whichever is greater. As with the calculation for Table 1 it is the most refrigerant that could be lost by a single release. The exhaust fans must remove air from the Machinery room at this rate whenever the concentration of refrigerant in the room exceeds the TLV- TWA (Threshold Limit Value - Time Weighted Average) of the refrigerant. Typically the fan is connected to the refrigerant monitor to assure that it operates when the refrigerant level reaches the TLV-TWA. As a reminder, the TLV-TWA is the amount of a substance that an average person can be exposed to for 8 hours a day, 40 hours per week, for a normal working lifetime and not experience any ill effects. Section where: Q = airflow (cu ft per minute) G = mass of refrigerant (lbs)

Suggested exhaust fan location … Exhaust Fan While the intent of the exhaust fan is clearly to remove refrigerant from the equipment room Standard 15 doesn’t provide specific instructions on how to locate the exhaust fan. It does include the following comments: “Openings for inlet air shall be positioned to avoid recirculation. Air supply and exhaust ducts to the machinery room shall serve no other area. The discharge of the air shall be to the outdoors in such a manner as to to cause a nuisance or danger.” Because all refrigerants are 3 to 5 times heavier than air the tendency is for refrigerant vapor to accumulate near the floor. For this reason it is appropriate to locate the inlet to the exhaust fan below the breathing zone. Typically less than 4 feet above the floor level. It should also be positioned to provide good air movement within the MER. Ideally fan operation will provide an “air sweep” across the refrigeration equipment. Section and 6 Feet

Exhaust Airflow End View Plan View Ventilation Airflow Dual-purpose ventilation system … Ventilation fans may also be used to remove heat or smoke from the MER. For this application the inlets are typically near the ceiling. A ventilation system that removes heat and refrigerant may require openings at both the floor and ceiling as shown.

Doors, passageways and access Refrigerant monitoring Open-flame devices Pressure-relief piping General requirements The next topic is Refrigeration system placement

equipment room design … Refrigeration System Placement
Unobstructed space for inspecting and servicing equipment Must comply with applicable safety standards and requirements of the presiding regulatory agency Clear head room not less than 7.25 ft below equipment over passageways In reference to placement of refrigeration equipment within the MER Std 15 only states : “A machinery room shall be so dimensioned that parts are accessible with space for service, maintenance, and operations. There shall be clear head room of not less than 7.25 ft below equipment situated over passageways.” Section As mentioned earlier, another consideration is chiller placement with respect to the ventilation system inlet and outlet.

equipment room design … Refrigeration System Placement
Multiple-chiller equipment room layouts … Refrigeration Systems Exhaust Fan Air Inlet Exhaust Fan Arrangement A is ideal because it provides excellent air movement across the chillers. Arrangement B is not quite as good as A because there is a stagnant area in the lower right hand corner but this is still a reasonable arrangement. Air Inlet Exhaust Fan Air Inlet Refrigeration Systems Refrigeration Systems Exhaust Fan Arrangement A Arrangement B

Doors, passageways and access Refrigerant monitoring Open-flame devices Pressure-relief piping General requirements The Standard states several important points in regard to doors, passageways and access.

equipment room design … Doors, Passageways And Access
Equipment room access limited to authorized personnel Adequate number and type of doors No openings to other parts of the building No “shared” air-handling systems 1) Access to the Machinery room is limited to authorized personnel. 2) There must be an adequate number of doors to ensure that people can escape in an emergency. 3) Doors must be tight-fitting and open outward. They also must be self- closing if they open into a building. 4) There shall be no openings that will permit passage of escaping refrigerant to other parts of the building. This includes any pipe tunnels, conduit raceways, openings around pipes, etc.. 5) Air handling units must not transfer air to or from an occupied space from or into a machinery room. Air handling units and ductwork that serve other parts of the building can be located in the machinery room provided that any openings are tight fitting and gasketed so that air from the machinery room can not enter or exit. See sections , , and 11.1

Doors, passageways and access Refrigerant monitoring Open-flame devices Pressure-relief piping General requirements There has been a lot of confusion about the next topic, refrigerant monitoring, probably as a result of the changes to this section in recent revisions of the Standard.

equipment room design … Refrigerant Monitoring
“Detector” must … Be appropriately sensitive to the refrigerant(s) in use Activate alarm and ventilation at TLV®–TWA “Threshold Limit Value–Time Weighted Average” Past versions of the Standard required oxygen deprivation sensors for some refrigerants and refrigerant detectors for other refrigerants. The current version of the standard simply states: “Each machinery room shall contain a detector, located in an area where refrigerant from a leak will concentrate, which shall actuate an alarm and mechanical ventilation in accordance with at a value not greater than the corresponding TLV-TWA( or toxicity measure consistent therewith).” The important points of this paragraph are: 1) Pick a detector that will actuate at or below the TLV-TWA. 2) Put the sensor in a location where refrigerant is likely to concentrate. 3) Upon actuation the detector must signal an alarm. 4) Upon actuation the detector must start the ventilation at the rate defined in section See section

Sensor location and placement … Height: 18 inches above the floor Plan Continuous ventilation: Between the refrigeration system and room exhaust Intermittent ventilation: Close to the refrigeration system, between it and the room entrance The only requirement of the Standard when locating the sensor is to put it “in an area where refrigerant from a leak will concentrate.” Manufacturers of refrigerant detectors provide additional instruction on where to place the sensor. Typical instructions would include height and plan recommendations. Since all refrigerant vapors are 3 to 5 times heavier than air the sensor is placed near the floor, but not so close as to cause nuisance alarms. Typically inches above the floor. Plan location is a little more difficult. If the room is continuously ventilated the ventilation air movement will carry refrigerant from a leak. In this case the sensor should be located “downstream” of the refrigeration equipment. If the ventilation equipment is not run continuously and there is not an obvious location where refrigerant will concentrate the sensor is typically located either near the refrigeration equipment or near the entry doors but not more than 50 ft from the unit.

Typical refrigerant monitor installation … Roof Or Concrete Floor Occupied Space Mechanical Equipment Room When undisturbed by air currents refrigerant vapor will tend to sink to the floor and fill the room from the bottom up. Because refrigerant vapor is 3 to 5 times heavier than air it has a tendency to displace the air. As a result the greatest danger of exposure to refrigerant in a machinery room is asphyxiation. Placing the sensor 12 to 18 inches above the floor is intended to provide early detection. The logical extension of this is to place the sensor on the floor but this is not recommended. Tests have shown that placing the sensor too close to floor gives falsely high readings. False readings or “nuisance alarms” should be avoided because the natural reaction to false alarms is to disable the monitor. Another cause of nuisance alarms is a monitor that is not refrigerant specific. Some of the lower cost monitors are sensitive to a host of other chemicals including cleaning fluids and paints. Refrigerant Monitor Sample-In Tubing 5 Feet Particle Filter Chiller 12–18 Inches

Suggested sensor placement for intermittent ventilation … In the typical two chiller equipment room the sensor is often located between the two chillers. In the figure shown a single sensor may not provide sufficient coverage so a second sensor is used. The two sensors are located close to the equipment but also close to the entry doors. Refrigeration Systems Identifies refrigerant sampling points

Typical multichannel scanner application … When multiple sensors are required because a room is large, or has a pit area, or a separate storage area the use of a multi-channel scanner may be appropriate. The multi channel scanner feeds several pickup points into a single refrigerant monitor. Samples are pulled from each location and fed into the monitor on a rotational basis to prevent dilution. Refrigerant Monitor With Multichannel Option Pit Identifies refrigerant sampling points

Doors, passageways and access Refrigerant monitoring Open-flame devices Pressure-relief piping General requirements In general Standard 15 doesn’t prohibit other equipment from being in the machinery room, however, it does make some specific restrictions for open flame devices.

equipment room design … Open-Flame Devices
“No open flames that use combustion air from the machinery room shall be installed where any refrigerant is used.” Exceptions … Combustion air is ducted from outside and sealed to prevent refrigerant leakage into the combustion chamber A refrigerant detector is used to shut down combustion automatically if a refrigerant leak occurs Specifically, it states that “No open flames that use combustion air from the machinery room shall be installed where any refrigerant is used.” Open flame devices include, but are not limited to, boilers and direct fired absorption equipment. This restriction caused some hardship especially in existing equipment rooms that contained boilers. As a result of input to the committee the following two cases are considered acceptable: 1) “combustion air is ducted from outside the machinery room and sealed in such a manner as to prevent any refrigerant leakage from entering the combustion chamber, or 2) “ a refrigerant vapor detector is employed to automatically shut down the combustion process in the event of a refrigerant leakage.” Condition 1) requires a boiler that is designed to bolt up to an inlet air duct. Condition 2) requires that the refrigerant monitor is tied to the boiler so that when the monitor detects refrigerant the boiler is automatically shut down. See section

Doors, passageways and access Refrigerant monitoring Open-flame devices Pressure-relief piping General requirements The standard states some very specific requirements for discharge piping. Pressure-relief piping from rupture discs, relief valves and purge systems must be piped outdoors to a location at least 15 ft above the ground and 20 feet from any building opening. The relief line shall be terminated in a manner that will prevent debris from blocking the opening and such that discharged refrigerant will not spray on people. See Section 9.7.8, 8.16

equipment room design … Pressure-Relief Piping
(Alternate Arrangement) Roof Suggested refrigerant vent piping … Exterior Wall Support this pipe! Flexible Steel Connection Purge Discharge Vent Line This figure shows Trane’s recommendations for piping the rupture disc. All materials used in the rupture disc system, such as the vibration isolation at the unit, must be compatible with the refrigerant being used. Another case where compatibility is important is in the use of PVC or other plastic pipe for discharge lines. Check the local code before installing PVC vent lines. ASHRAE Std 15 doesn’t prohibit the use of PVC, however, some local codes do. Rupture Disc Assembly 15 Feet Above Ground Level Drip Leg (Length As Needed) 1/4” FL × 1/4” NPT Drain Valve

Doors, passageways and access Refrigerant monitoring Open-flame devices Pressure-relief piping General requirements The General Requirements section (Section 11) covers the “odds and ends” of the requirements of the machinery room.

equipment room design … General Requirements
Signs Changing, charging and storing refrigerants Self-contained breathing apparatus Two required per equipment room Emergency shutdown procedure General maintenance Because this section covers a lot of little details it is reprinted in it’s entirety on page 22 of REF-AM-3 (Jan 95). The type of topics covered in the General Requirements section are: Signage indicating the name and address of the installer, type and amount of refrigerant and lubricant, etc. In regard to changing, charging and storing refrigerants, the most interesting is the storage limit of 330 lbs of refrigerant in approved storage containers. This limit can be exceeded if the storage vessel(s) meet the requirements of section 9.7. Section 9.7 covers pressure vessel design and requires relief valves that are piped outdoors. The 1994 version of the Standard requires 2 self contained breathing apparatus. This is a change from the 1992 version which required 1 SCBA and strongly recommended a second. This is the short list of topics covered by the General Requirements section. While numerous the items in this section are not complicated and it would be best to read through them to see which ones would be the most interest to the audience. See section 11

An American-Standard Company
An American-Standard Company To wrap up, this presentation covered the portion of ASHRAE Standard 15 that applies to those systems that must be installed in a machinery room. The intent was to review the applicable portions of the standard and provide additional design recommendations where where the Standard left off. This presentation is not intended to replace the Standard. The Standard is available from ASHRAE or through Trane and is recommended reading. It is also important to recognize that the Standard also applies to all other installations of refrigeration equipment. Trane publication REF-AM-3 “Refrigeration System Equipment Room Design” is follows this presentation closely and is a good reference source for questions on this topic.

Refrigeration System Equipment Room Design

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