Appendix_C_DIV_23_Instrumentation_and_Control.docx

23 09 00 Instrumentation and Control for HVAC 23 09 23 Direct Digital Control Systems for HVAC 23 09 23.13 BACnet Direct Digital Control Systems for HVAC All Direct Digital Control (DDC) project engineers, managers, designers, installers, and operators shall understand and comply not only with this Section, but must understand, design, install, and implement DDC systems in compliance with the products and requirements outlined in Division 25.

All DDC designs, installations and repairs shall comply with ES521s technical specification for BACnet DIRECT DIGITAL CONTROL SYSTEMS (DDC) FOR HVAC.

New and Legacy DDC Systems Legacy systems are systems that were installed prior to June 2012. These systems shall be maintained and repaired by the original equipment manufacturer utilizing best industry practices for the installed systems. The materials outlined in the BACnet Direct Digital Control (DDC) Specification are permitted to serve as a basis for materials in legacy systems when component or device replacement is required.

The requirements outlined in this Section pertain specifically to new DDC systems, as well as to the repair or expansion of compliant legacy systems. Persons working on a DDC system are encouraged to clarify through ES521 if the system is considered a legacy system.

Compliance with DoD instruction 8500.2 The products, configurations and materials outlined in this Section and Division 25 are tested for compliance with DoD instruction 8500.2. Deviations from the products, configurations, installation requirements or materials listed in this Section and Division 25 are not permitted without written approval from the Chief of Facilities Engineering (ES521). Acceptance of a proposal by the Government that does not clearly indicate the materials, products, installation methods and configurations used to develop the proposal does not relinquish the bidder from compliance with this Section and Division 25.

Notice to DDC Designers Designers of DDC systems shall utilize the BACnet Direct Digital Controls (DDC) Specification as the base specification for their controls design. The designer shall modify the specification as necessary to accommodate the requirements of the project. At no time shall the designer directly substitute the specifications without project specific modification to the specifications. The designer shall provide clear indication during each design submittal review what words, sections, materials, products, installation requirements were modified in the BACnet Direct Digital Control (DDC) Specification.

Discussion of DDC Performance Verification Testing (PVT) The intent of PVT is to require the DDC designer and installer to ensure that the DDC system will function as intended and designed prior to the initiation of Functional Performance Tests (FPTs) or Integrated Systems Tests (ISTs) as part of the formal commissioning process required for all DDC and similar controls projects.

DDC Operator Requirements Operators of DDC systems shall:

· Be familiar with the specifications outlined in the BACnet Direct Digital Controls (DDC) Specification;

· Comply with the security requirements outlined in section 1.7 the BACnet Direct Digital Controls (DDC) Specification; and,

· Comply with the training requirements outlined in Division 25.

DDC Enterprise Contract ES521 shall maintain a contract to maintain, repair and install DDC systems. The contract shall have the ability to deliver DDC services to any DISA ESD facilities.

The ES521 DDC program shall work closely with the ES521 BOS/O&M program to ensure that the programs do not duplicate efforts or create contractual conflicts or disputes.

23 12 13 Facility Fuel-Oil Pumps

23 12 16 Facility Gasoline Dispensing Pumps

23 13 00 Facility Fuel-Storage Tanks

Fuel Oil Storage Systems

The system used for storage and handling of fuel oil shall comply with requirements of NFPA 30, “Flammable and Combustible Liquids Code.”

All tanks operating above atmospheric pressure shall be designed and fabricated in accordance with the ASME Boiler and Pressure Vessel Code Section VIII, “Rules for Construction of Pressure Vessels”, Division 1 – Unfired Pressure Vessels.

All tanks operating at or below atmospheric pressure shall be designed and fabricated to the applicable design standards listed in NFPA 30, Chapter 4.

New and replacement fuel storage systems shall be above-ground and located within a liquid- tight containment to control spills and leaks.

Fuel Systems

On-site fuel supply shall be available through a piping system to all generators. Fuel system valves shall be tagged as to function and operation position. Day tanks will have bypass valves for electrical solenoids. Cleanable filters shall be installed on all fuel lines to prevent equipment damage from impurities and debris.

Fuel and fuel systems shall be tested at least triennially for quality and fuel contaminants. Fuel systems shall have a minimum of 72 hours of fuel available by either on site storage or through support agreements. The system used for storage and handling of fuel oil shall comply with requirements of NFPA 30, “Flammable and Combustible Liquids Code.”

DISA shall maintain fuel and tank systems using a fuel stabilizer product in between scheduled testing and cleaning cycles. Products and procedures are described in detail in O&M Module 3 in TIM.

23 20 00 HVAC PIPING AND PUMPS

Legacy datacenters are designed with a single, non-redundant chilled water distribution system, generally located under the access floor. This non-redundant design limits the ability of the facility to maintain availability or to recover from an incident involving the chilled water distribution, and represents the single greatest threat to continued operations at DISA datacenters today. Future datacenters will be designed with redundant cooling distribution systems to reduce this operational risk. HVAC upgrade projects shall take this risk into account and provide risk reduction strategies (up to but not necessarily including installation of a redundant distribution system) suitable for the facility mission and planned obsolescence date.

Chilled water piping is traditionally installed under the access floor to support CRAC units. The design of these subfloor piping distribution systems shall be optimized with the DCM zone designs (see section 13 01 21.10) so as not to impede underfloor plenum airflow when required. In general, this shall indicate that piping shall be installed along perimeter walls where practical, and shall minimize intersections, junctions, and bends to maximize efficiency of fluid flow.

DISA Enterprise Services Facilities Engineering (ES521) DISA CSI 360-95-3 Facility Standards, v3.2.5 10 May 2012

Piping, pumps, flanges, and valves shall be thermally and acoustically insulated to the maximum extent practical. Piping shall be color-coded and labeled IAW section 01 67 00 (Facility and Device Labeling and Identification). Insulation shall be maintained in good condition.

Chiller Piping

Chilled water piping shall be fabricated and installed in accordance with the American Society of Mechanical Engineers Code for Pressure Piping, B31.9, “Building Services Piping”.

The exterior surface of buried pipe shall be coated per AWWA C209 (type to be specified by Project Engineer) and AWWA C214.

Teflon tape type thread sealant and lubricant maybe used.

Stud bolts shall be of sufficient length to allow a minimum thread engagement of 1 bolt diameter. Chill Water Piping Material Specification

PIPES:

Diameter

Design/Material

½” – 2”

Schedule 80, Seamless Carbon Steel, ASTM A106, Grade B.

2-½” – 10”

Schedule 40, Seamless Carbon Steel, ASTM A106, Grade B

12” – 24”

Standard weight, Seamless CS, ASTM A106, Grade B

VALVES (see valve specification sheets):

TYPE

Design/Material

≤ 2”

BALL

Full Port, Threaded Carbon Steel

CHECK

Class 800, Threaded Carbon Steel

GATE

Class 800, Threaded Carbon Steel

> 2–½”

BALL

Full Port, Class 150 Flanged Carbon Steel

CHECK

Check, Class 800 flanged Carbon Steel

GATE

Gate, Class 800 Flanged Carbon Steel

FITTINGS:

Design//Material

ANSI B16.11, Threaded Class 8000, Forged Carbon Steel, ASTM A105.

Swages ASTM A106, Grade B to match pipe schedule

Hex head plugs per ASTM A105

ANSI B16.9, Butt-weld, Seamless Carbon Steel, ASTM A234, Grade WPB, same schedule as pipe.

12” – 24”

Standard weight, Seamless CS, ASTM A106, Grade B

UNIONS

MSS SP-83, threaded, class 3000, forged carbon steel, ASTM A105

FLANGES

(Normally use unions), flanges ANSI B16.5 threaded, class 150 raised face, forged carbon steel, ASTM A105.

ANSI B16.5 weld-neck, class 150 raised face carbon steel, ASTM A105. Same schedule as pipe. Weld neck flanges are preferred, however, slip-on flanges are acceptable.

BRANCH RUNS

Headers - Use threaded tees and reducing tees

Branch 2” and smaller, use Class 3000, thread-o-let, ASTM A105. Branch 2-1/2” and larger, use weld-o-let, ASTM A105. Same schedule as pipe.

BOLTING

Item

All Sizes

Stud Bolt

Alloy Steel, ASTM A193, Grade B7.

Nuts

Heavy Hex, Alloy Steel ASTM A194, Grade 2H.

Washers

Type B, Narrow Series, Carbon Steel, ASTM F844

GASKETS

All Sizes

150 pound ring type, 1/8” thick, Garlock Gylon style 3510

TORQUING

Pipe

(in)

Bolt Size

No. of Bolts

Torque/Bolt

(Ft-lbs) (1)

Torque/Bolt

(Ft-lbs) (2)

½

½ - 13

¾

1-¼

1-½

2 – 4

5/8 – 11

4 / 8

5 – 8

¾ - 10

10 & 12

7/8 - 9

14 & 16

12 / 16

18 & 20

16 / 20

– Recommended Torque/Bolt

– Maximum Torque/Bolt

BALL VALVE SPECIFICATIONS

VALVES - 2 INCH AND SMALLER

VALVES – 2 ½ INCH AND LARGER

TYPE FLANGED, FULL PORT

STANDARDS CLASS 150, ANSI B 16.34, ANSI B 16.10

ENDS CLASS 150, FLANGED, RAISED FACE ANSI B16.5

BOLTING MANUFACTURER’S STANDARD HANDLE MANUFACTURER’S STANDARD

NOTE: End-To-End Dimensions May Vary Between Manufactures.

CHECK VALVE SPECIFICATION SHEET

VALVES - 2 INCH AND SMALLER

TYPE CHECK, PISTON

STANDARDS CLASS 800, API 602

BODY GASKET MANUFACTURER’S STANDARD

VALVES – 2 ½ INCH AND LARGER

TYPE CHECK, SWING

STANDARDS CLASS 150, ANSI B 16.34, API 6D

ENDS

CLASS 150, FLANGED, RAISED FACE ANSI B16.5, 250 RMS MAX

NOTE: End-To-End Dimensions May Vary Between Manufacturers.

GATE VALVE SPECIFICATION SHEET

VALVES - 2 INCH AND SMALLER

VALVES – 2 ½ INCH AND LARGER

TYPE GATE, FLANGED

STANDARDS CLASS 150, ANSI B 16.34, API 600

ENDS CLASS 150, FLANGED, RAISED FACE ANSI B16.5

BODY AND BONNET

CARBON STEEL, ASTM A216, GRADE WCB OR ASTM A105

SEAT STELLITE FACED, RENEWABLE OR EQUAL

STEM 13% CHROME, STAINLESS STEEL

DISC WEDGE

13% CHROME, STAINLESS STEEL SOLID WEDGE OR FLEXIBLE

TRIM 13% CHROME, STAINLESS STEEL STEM PACKING MANUFACTURER’S STANDARD BONNET TYPE BOLTED NOTE: End-To-End Dimensions May Vary Between Manufacturers.

23 21 00 Hydronic Piping and Pumps

23 21 13 Hydronic Piping

23 21 13.13 Underground Hydronic Piping

23 21 13.23 Aboveground Hydronic Piping

23 21 13.33 Ground-Loop Heat-Pump Piping

23 21 23 Hydronic Pumps

23 21 23.13 In-Line Centrifugal Hydronic Pumps

23 21 23.16 Base-Mounted, Centrifugal Hydronic Pumps

23 21 23.19 Vertical-Mounted, Double-Suction Centrifugal Hydronic Pumps

23 21 23.23 Vertical-Turbine Hydronic Pumps

23 21 29 Automatic Condensate Pump Units

23 25 00 HVAC Water Treatment

Water treatment and sampling is a critical component in optimizing efficiency of HVAC (heat transfer) systems, as well as the primary tool for monitoring equipment and piping condition. A cooling tower that can supply condensing water at one degree lower temperature can increase the efficiency of the chiller by two to three percent, which represents significant utility savings.

23 25 10 Water Treatment Program Goals & Guidance

Water treatment systems shall be planned, designed, and procured to meet water usage and pollutant reduction goals. ES521’s goal is to have process water treatment in all CSD facilities be chemical-free by the beginning of fiscal year 2019.

In the majority of industrial and process facilities since WWII, chemical treatment has been the primary accepted method of water treatment for cooling, heating, and other process water applications. Acids are used to remove salts and other scale materials from the metal surfaces. Biocides are used to kill organic life in the water. Corrosion inhibitors are used to retard the corrosive elements in the water. Until recently (circa 2000), these have been the only proven, reliable ways to maintain clean process water and the heat transfer surfaces necessary for efficient operation of HVAC equipment.

The negative environmental impacts of chemical water treatment include the disposal of chemicals into the atmosphere and municipal water/sewage systems and increased make-up water usage requirements.

The water treatment for all hydronic systems, including humidification systems, shall be designed by a qualified specialist. The design system shall address the three aspects of water treatment: biological growth, dissolved solids and scaling, and corrosion protection.

Each individual location will require a different water treatment program based on local water, and installed equipment type, size, and construction materials. UFC 3- 240-13FN, “Industrial Water Treatment Operation and Maintenance,” shall be used in development and for gauging performance effectiveness of water treatment programs. Specific guidance for design target parameters and frequencies of service required on cooling towers and other treated systems are covered in detail in TIM, the Enterprise Operations & Maintenance Management Services Standard (DISA CSI 360-95-3A).

23 25 20 Chemical-Free Water Treatment Systems

When HVAC system upgrades (including but not limited to chiller or cooling tower replacements) and new HVAC system installations are programmed for CSD datacenters, chemical-free treatment systems shall be installed in lieu of chemical- based systems.

DISA has a corporate goal (strengthen environmental & energy management) supporting Executive Order 13423, “Strengthening Federal Environmental, Energy, and Transportation Management.” In accordance with guidance from Executive Order 13423 § VI(A)(7), ES521 intends to reduce the enterprise impact through reduced water consumption intensity (13423 sections 2(a) & 3(a)(iii)) and reduction of toxic or hazardous chemical usage (13423 sections 2(e)(i) & 3(a)(vi).

Industry estimates for installation of chemical-free systems include 1,000 gallons of water usage saved per ton of used condensing capacity, a decrease of 40% of blowdown, and a decrease of 15% of makeup water usage.

Blowdown water shall be recycled for other facility non-potable water uses. Designs for water treatment systems shall include provisions to divert (chemical-free) blowdown water for non-potable reuse. Options may include storage for makeup water feeds, maintenance use, or landscaping.

23 25 30 Chemical-Free Water Treatment System Specification

These technical requirements designate the salient characteristics of a non-chemical water treatment system for open cooling towers of evaporative condensers and all components (filtration system, conductivity meters, blow down actuators, et cetera) necessary for a completely automated stand-alone system.

A. No specific technologies are specified. Proposed systems shall be reviewed by ES521 for technical acceptability prior to purchase or installation in a CSD datacenter facility.

B. The system shall be capable of effectively controlling scale, corrosion, and bacteria in open cooling towers and evaporative condensers without the use of chemicals. The system blow down shall contain no added chemicals and shall conform to all sewer discharge regulations.

C. The system shall maintain the following re-circulated water parameters:

i. Conductivity range of 300 to 5,000 µS/cm. (Note: This is a general conductivity range. A more specific operational range for each installation shall be determined through an examination of the chemistry of the source water during planning and installation.)

ii. pH range of 7.2 to 9.4.

iii. Total bacteria count (TBC) of less than 10,000 CFUs/ml.

D. The system shall have the following electrical and control characteristics:

i. Operate on 480V 3-phase input as standard.

ii. Meet UL specifications for electrical components.

iii. Controls are enclosed in a water-resistant shell and be provided with indicator lights that signify the system is on and operational.

iv. Automation controls for monitoring the system’s operation and performance, and for controlling the treatment process shall be provided with the system. Automation controls shall be MODBUS and meet all current requirements of the specified DISA-standard Building Automation System (BAS) specification (see section 25 10 00).

v. Automation controls, meters, and monitors for monitoring the treated water loop’s performance, including metered make-up and blow-down water metering, system temperature, and automatic water condition sensors for monitoring re-circulated water parameters noted above. Automation controls shall be MODBUS and meet all current requirements of the specified DISA- standard Building Automation System (BAS) specification (see section 25 10 00).

E. The system shall have the following physical (construction) characteristics:

i. Electrical panel is in a NEMA 4X enclosure.

ii. The treatment system shall consist of a water treatment unit, filtration element(s), and related control elements.

iii. Filtration units shall be accessible, cleanable, user-maintainable, user- replaceable, and of long life (>1 year of operation). A five (5) year supply of replaceable filters, if needed, shall be provided with the unit.

F. The system shall provide physical water treatment by:

i. Controlling scale formation on all heat transfer surfaces (including fill, coils, pipes, heat exhangers, valves, and other components in the system).

ii. Controlling the population of microorganisms such as bacteria to 10,000 CFU/ml or below when measured using plate count agar at 35°C.

G. The system shall provide for reduced water consumption through the reduction of blow down due to increased cycles of concentration while adequately controlling scale, corrosion, and bacteria levels within the system.

H. Factory-trained representative shall provide installation support as follows:

i. Supervise customer personnel in all piping and electrical hook-ups associated with the treatment program and give direction to sampling, monitoring, blow down, and passivation required to ensure acceptable water chemistry of the system (training).

ii. Immediately after hydrostatic testing of piping is completed, drain, flush, clean and passivate, and refill with clean water prior to system being placed into operation.

iii. Monitor performance of the system not less than monthly for the first twelve months of operation with checks including the following:

instrumentation related to blow down

performed within 90 days of installation and every 60 days subsequent

• Conduct trend analysis on water treatment results

iv. Provide monthly maintenance support services over the lifetime of the equipment to include:

Chemical Water Treatment Systems)

Service Provider (or Facility Manager) for condition recording and trend analysis.

I. Warranty. The system and all components shall be fully warranted to function as designed for the water conditions at the installation location for not less than two (2) years from date of commissioning and acceptance by the Government. Replaceable filter elements shall be warranted and pro-rated for their promised lifecycles. The warranty shall include onsite technical support to diagnose and repair as necessary the system to working condition, at the vendor’s cost. Travel costs (including per diem) for warranty work shall be paid by the Government in accordance with the Joint Travel Regulation.

23 25 50 Legacy Chemical Water Treatment Systems

The performance of chemical water treatment systems shall produce, as a minimum, the following characteristics; hardness: 0.00; iron content: 0.00; dissolved solids:

1,500 to 1,750 ppm; silica: 610 ppm or less; and a PH of 10.5 or above. The system shall operate with an injection pump transferring chemicals from solution tank(s) as required to maintain the conditions described. The chemical feed system shall have self-contained controls that can be integrated with the building automation system (BAS) for monitoring and control.

Required tests and frequencies cannot be stated for all possible conditions. The following are the minimum that are anticipated to be tested for and reported upon by a reliable water treatment vendor.

Boilers Cooling Towers Closed Loop Systems

Conductivity of soft water

Make up water conductivity

Conductivity

Hardness of soft water

Molybdenum

Feed water conductivity pH pH

Feed water hardness

Conductivity/TDS

Neutralized conductivity

ATP

P-alkalinity

Corrosion coupon monitoring

Sulfite

M- alkalinity

Calcium hardness

Condensate conductivity

Inhibitor

Condensate hardness

Condensate pH

23 26 00 Leak (Water) Detection Systems

The current baseline for design and installation shall be or of equivalent capability to a TraceTek TTDM-128, controller/module and TT1000-50FT-PC water sensing cable. Consult ES521 for varying design.

System Description

A centrally monitored water detection system shall be installed in all raised floor computer rooms. Multiple independent monitors, non- locating monitors (i.e.: local alarms) and/or non- reporting monitors are not acceptable. Only one device shall monitor all raised floor per site. If maximum linear distance is exceeded with proper installation, use of zone feature of the device and components is acceptable. The system shall detect presence of water underneath raised floor areas in case of emergencies. Liquid cooled/cooling or liquid heated/heating devices and distribution lines in the computer rooms shall be monitored at the subfloor base of the raised floor computer room. Do not interconnect multi-manufacturer cables. Use only the same type of sensing cable throughout the system.

Control Module

A central monitor shall receive all alarms/warnings of any detected water under the raised floor and provide an accurate location resolution of ± 10 ft. Do not install in hazard locations, battery rooms or unmonitored areas (see installation, subsequent section). Use 120V, 1Ph, and 60Hz power not supplied by Critical Bus UPS. Device shall be capable of monitoring 5000 ft of cable. Control module shall have an audible alarm (switchable), digital readout for distance/location of detected leak/alarm on physical floor space, data logging, a control panel for acknowledgement and alarm-reset function.

Communication

The central monitoring device (Control Module) shall be capable of communicating the alarm/warning to a Building Automation Systems BAS, host computer, PLC devices, dial-out and paging. RS232/RS485 interface is preferred.

Installation

The central monitoring unit shall be located within the DISA facility of 24x7x365 occupancy. This is typically addressed if installed within an Operations/Help Desk area. The sensing cable shall be installed and secured atop structural floor surface. Other items in the raised floor void shall rest above the sensing cable. Installation acceptance and system operation shall be commissioned by manufacturer-certified installer to include testing and distance/map location calibration at end of each cable length. Prevent excess movement and vibration of sensing cables. Secure to subfloor with tie-down clips at a minimum of every 6 feet of straight distances, and before and after change of direction and/or elevation. False alarms: False alarms may be caused by dirt and dust. Raised floor subfloors should be cleaned.

Sensing Cable

Do not run power and sensing cable in the same conduit. Do not use sensing cables in excess of 50 feet. Install leader cables from monitoring device to the first sensing cable. Locating measurement of sensing cable shall begin within the raised floor area. Use jumper cables where the sensing cable would penetrate between floors, cable chase (enclosures), inter-room or unmonitored areas. This maintains distance/location calibration in close proximity to the cable lengths and ease of troubleshooting and alarm verification. A serial sensing cable topology shall be preferred over star or parallel configuration (see note, this section). Lay sensing cable first along the room perimeter then circumferentially at each device that use any type of process fluid, i.e.: CRACs, humidifiers, supply & return, condensate and drain piping, heaters, etc.

Location/Labeling

Tag and label each end of sensing cable at connector to next cable (approximately every 50 feet). Do not rely on cable length as locator. Measure actual cable length with manufacturer’s test portable device.

Documentation

Provide a location drawing referenced in a separate layer in Aperture, with actual reporting distances at connection points. Layer shall include monitoring device, sensing cables and other components downstream to the monitoring device. Contact ES521 for additional guidelines.

Inventory and Supplies

Site shall maintain 5% of total used sensing cable lengths and associated supplies. A test device shall also be maintained in order to troubleshoot, identify and isolate a particular section in the cable string.

Inspection and Maintenance

Each site shall perform inspection annually and maintenance as required. Inspection: follow manufacturer specification for troubleshooting and inspection.

23 30 00 HVAC AIR DISTRIBUTION

Computer Room Temperature and Humidity Control

The supply temperature to the computer room should be maintained within the range of 72 ± 2 °F. Relative room humidity should be maintained within the range of 50 ± 5% RH (45-55 RH).

This temperature range satisfies most IT equipment manufacturer’s recommendations. Relative humidity below 45 percent can cause electrostatic discharge (ESD) resulting in possible damage of integrated circuit boards and data loss within. Relative humidity above 55 percent can cause water condensation on IT equipment. These ranges should be used as maximum operating ranges. Narrower ranges should be specified for optimal environmental reliability. A temperature range of 70º to 74º F and a relative humidity range of 45% to 55% will allow for a much greater operational buffer in case of environmental support equipment downtime or other unexpected influences.

Provide a comprehensive room monitoring system, that appropriate conditions are being maintained throughout the entire room, and that the room is not being judged by the averages of its conditions, or by a single location. The subfloor pressure differential is an important aspect of conditioned air distribution, and air conditioning placement and capacity should consider this factor. It is necessary to continually balance room air conditioning with the changing heat load configuration to maintain appropriate conditions throughout.

23 30 05 Computer Room (Class I) Temperature and Humidity Control

The environmental conditions in DISA datacenters shall be maintained in accordance with ASHRAE TC9.9 recommendations. The datacenter environment is specifically designed and intended to support the IT equipment, and the environment shall not be conditioned for personnel comfort.

Datacenter temperature and humidity conditions shall be measured at the air intake to the IT equipment, rather than measuring the ambient or average condition(s) throughout the datacenter. For the purposes of this standard, measurements shall be taken at 48” height above the access floor, at the exterior of the closed perforated IT equipment rack door.

Comparison of 2004 and 2008 recommended operating envelope

Previous 2004 Version Current (2008 Version) Standard

Other enter environmental measurements may be recorded, but are not subject to this specification. For other purposes environmental measurements at those locations may be of some value. Some of those other measures may include:

⊗ Ambient or average datacenter temperature, at any height;

⊗ CRAC air returns;

⊗ Supply air at perforated access floor tiles; or, ⊗ In hot (exhaust) aisles.

Class I Datacenter Environmental Envelope plotted on standard psychrometric chart. See attached file “Environmental Envelope Psychrometric Chart.PDF” for a full-size, detailed working copy of this chart.

For simplicity, make the assumption that the atmospheric pressure is sea level at 101.04 kPa (29.921 inches of mercury), so that a standard psychrometric chart can be used. Except for significant elevation differences, the differentials between charts are generally not so significant that their use would alter the results of measurements or the implementation of these standards significantly.

The standard for the environmental envelope in DISA datacenters (all raised access flooring computer areas in DISA DECC facilities) is the 2008 ASHRAE TC9.9 recommended environmental envelope, primarily based upon dry bulb temperatures and (calculated) dew points from measured relative humidity.

For datacenter locations located at significant altitude (above 3,000ft ASL), derate the dry bulb temperature by 1.1°C (2 °F) per additional 1,000ft. Therefore, if a correctly measured dry bulb temperature at a datacenter in the mountain west of CONUS at 4,700ft ASL reads 26.1°C (79.0 °F), derate by (((4,700-3,000)/1000)*1.1 =) 1.9°C (3.4 °F) and therefore use a temperature of 24.2°C (75.6 °F) for calculation of the dew point or determining compliance with the environmental envelope on the psychrometric chart. (Air at higher altitude

DISA Computing Services CD521 Facilities Engineering

Datacenter Dewpoint Calculator

Dry Bulb Temperature °F 80.0 °F

Dry Bulb Temperature °C 26.7 °C

Relative Humidity (%) Elevation ASL 40% feet ASL

Elevation Above 3,000ft ASL 1700 feet Derated Dry Bulb Temperature °C 24.8 °C Normal Atmospheric Pressure (kPa) 101.04 kPa Saturation Vapor Pressure (kPa) 3.13 kPa Actual Vapor Pressure (kPa) 1.25 kPa Dewpoint Temperature °C 10.3 °C

Dewpoint Temperature °F 50.5 °F

Derived from methods presented on pp176-7 of Jensen, M.E., R.D. Burman, and R.G. Allen (ed). 1990. “Evapotranspiration and Irrigation Water Requirements.” ASCE Manual and Report on Engineering Practice No. 70, New York, 332 p.

ES521 has created the above Datacenter Dewpoint Calculator for use in generating dewpoints from dry bulb temperature and relative humidity measurements to allow users to accurately determine whether measurement points are within the prescribed datacenter environmental envelope. See attached file “Dewpoint Calculator.xlsx” for a full working copy of this tool.

has a lower capacity to hold moisture.)

While the entire area inside the defined envelope is technically acceptable for the datacenter environment (as measured at the IT equipment air intake), the lowest energy usage for environmental support equipment such as chillers generally occurs on the right side of the envelope, at higher temperatures. Based on energy-reduction guidelines discussed in depth in CSI 360- 95-3A (TIM, the Enterprise Operations & Maintenance Services Standard), DISA datacenters should be maintained at an inlet temperature of between 74 °F and 80 °F where possible.

23 32 00 Air Plenums and Chases

23 32 13 Fabricated, Metal Air Plenums

23 32 33 Air-Distribution Ceiling Plenums

23 32 36 Air-Distribution Floor Plenums

Design static pressure for access (raised) floor plenums is 0.15” of H20 water column (WC), which should yield approximately 900CFM of airflow through perforated tiles. This design pressure will sustain approximately 3500W (1 ton) of cooling through each perforated tile (citation: www.datacentresols.com/news/webnews-full.php?newsid=5682).

The governing equation is BTU/h (amount of cooling) = 1.081 * CFM * ΔT, where ΔT is the temperature rise (through the servers, at the CRAC cooling coils, et cetera).

12,000BTU/h is one ton (3,514W). At a 900CFM design flow rate, a standard 27° F temperature rise yields 26,268BTU/h (2.19 tons).

At a more realistic .025” WC expected in the datacenter due to non-engineered openings and pressure losses through these, we expect a 390CFM flow, supporting 11,383BTU/h (0.95 tons) per floor tile.

23 40 00 HVAC AIR CLEANING DEVICES

23 41 00 Particulate Air Filtration

Computer room air conditioning (CRAC unit) filters will be designed to remove particles larger than 20 microns. Filters shall be checked at least monthly and changed as necessary. Mechanical air filters must be rated at a minimum initial atmospheric dust-spot efficiency of 40 percent. Electrostatic air filters are designed to operate at 85 to 90 percent efficiency at a given face velocity, depending on equipment and conditions in the datacenter.

Centralized air supply systems for both administrative and datacenter spaces shall have HEPA air filtration systems (capable of removing at least 99.97% of airborne particles

0.3 micrometers (µm) in diameter, with higher efficiencies for larger and smaller particles) and ultraviolet antimicrobial lighting systems (fully operational when any vents, fans, or pressure differentials that could move air through the ductwork are in operation). These systems shall be inspected and maintained on a weekly basis with replaceable media/components being changed out per OEM recommendations.

Existing central HVAC systems shall be retrofitted with these systems to improve indoor air quality (IAQ) when and where practicable.

Special air filtration is necessary where installations are exposed to unusual dirt or dust conditions. Consider self-contained ambient air nuisance dust package units for ducted supply and return usage.

23 50 00 CENTRAL HEATING EQUIPMENT

23 60 00 CENTRAL COOLING EQUIPMENT

Chillers, cooling towers and pumps that provide cooling for IT equipment shall be configured to provide 100% redundancy (minimum 2N level) such that a loss of any system component does not significantly affect overall system performance or mission accomplishment.

The most efficient and cost-effective centralized cooling systems shall be chosen for installation to support DISA datacenter facilities. Careful and complete engineering assessments shall be made of future-technology systems prior to implementation, even in test cases – and this includes both central cooling and point-of-development solutions (for example, chip-based cooling). All solutions shall be evaluated for their impact both on cooling and on other systems, such as electrical usage and system efficiency.

Chiller Design

Chiller configuration should be such that requirements can be staged as required. There will be a backup capability. A connected load of 500 tons supported by three 300-ton units (N+1) would satisfy this requirement (although not mandatory 2N redundancy requirements). This configuration allows normal full load with 100-ton surge/spare capacity and one complete system to accommodate maintenance requirements. Each chilled water unit should have individual supporting pump units and manual isolation valves. The system shall be capable of producing 42 °F chill water continuously.

The chilled water system shall conform to the EPA requirements for hydro-chlorofluorocarbons (CFCs).

Water Treatment

Water used in chilled water systems and boilers must be regularly tested and treated. Provide a water meter on the make up water supply line to help evaluate the treatment process. Water testing and treatment will be conducted and documented on all systems, both open and closed.

Metering and Gauges

Provide a robust amount of meters and gauges in every system to facilitate troubleshooting, maintenance and system performance evaluations, and to allow baselining of HVAC system usage and efficiency.

Condenser Water Heating

Provide capability to heat condenser water to prevent the water temperature from going too low thus causing the chiller to shut itself down.

Control System Failures

This includes all Direct Digital Control (DDC) and pneumatic systems. Ensure that equipment is commanded to the appropriate state in case of power failure. Normally this means control valves will not move in the case of a control system failure. They will typically remain in the same position as before the power failed

23 61 00 Refrigerant Compressors

DISA does not specify any particular chiller system – rotary, centrifugal, scroll, or other for producing chilling fluid to cool the datacenter. Both chilled water and glycol chilled water solutions are both appropriate for the regular datacenter cooling solution. This is not meant to state that alternative systems, fluids, or other are unsuitable for the datacenter environment. Ozone-Depleting Refrigerants Installation of refrigeration systems, i.e. chillers, using the refrigerants, R-11, R-12, R-113, R-114, R-115, or R-500 will not be permitted at DISA Enterprise Services sites. Refrigerants in new chillers shall have an Ozone Depletion Factor (ODF) of 0.05 or less. The ODF shall be in accordance with the Montreal Protocol On Substances That Deplete the Ozone Layer, September 1987, sponsored by the United Nations Environment Program.

Flammable refrigerants

Chillers that employ the HFC 123, 124, and 132 series refrigerants will be separated from flame producing devices in accordance with ASHRAE 15.

Low Probability Systems

Design and install refrigeration with the classification of a Low Probability System. A low probability system is defined by ASHRAE 15-1994 as any system in which the basic design, or location of the components, is such that leakage of refrigerant from a failed connection, seal, or component cannot enter the occupied space.

High Probability Systems

High Probability Systems are defined by ASHRAE 15 as any system in which the basic design, or location of components, is such that leakage of refrigerant from a failed connection, seal, or component will enter the occupied area. A typical high probability system is the packaged chiller systems placed directly on the computer room floor to provide cooling to chilled water cooled mainframes. High probability systems shall be installed only as a last option and specifically approved by ES521 before installation occurs.

Changes

A change in the type of refrigerant in a system shall not be made without the notification of the authority having jurisdiction (AHJ), the user, and due observation of safety requirements. The refrigerant being considered shall be evaluated for suitability.

Signs

In accordance with ASHRAE 15, each refrigeration system erected on the premises shall be provided with a legible permanent sign, securely attached and easily accessible indicating: the name and address of the installer, the refrigerant number and amount of refrigerant, the lubricant identity and amount, and the field test pressure applied.

Note: When the kind of refrigerant or lubricant is changed as provided above, there shall be new signs installed to identify the changes in accordance with ASHRAE 15.

Service Containers

No service containers shall be left connected to a refrigeration system except while charging or withdrawing refrigerant. Transfer withdrawn refrigerants to approved containers only. Except for discharge of pressure-relief devices and fusible plugs, incidental releases due to leaks, non-condensable purging, draining oil, and other routine operating or maintenance procedures, no refrigerant shall be discharged to the atmosphere or to locations such as sewer, river, stream, or lake.

Stored Quantities

The total amount of refrigerant stored in a mechanical room in all containers not provided with relief valves and piping IAW ASHRAE 15 shall not exceed 330 lbs (150 kg). Refrigerant shall be stored in containers that comply with the U.S. Department of Transportation Code of Federal Regulations 49, Chapter I, Subpart A, §173.306.

No refrigerants shall be stored in non-plant areas, even when operational systems are located in other areas.

23 62 00 Packaged Compressor and Condenser Units

Direct Exchange (DX) unit packages are appropriate for DISA facilities so long as they are designed using a 2(N+C) or higher redundancy model in an integrated design. Individual installations to increase single-system redundancy are not prohibited, but are strongly discouraged as they go against the model intended for overall system redundancy.

23 64 00 Packaged Water Chillers

Automatic Restart

Each chilled water system will have the capability to restart automatically one time after an unprogrammed shutdown, and will automatically notify the computer control center or Building Automation System of the outage and restart.

Eddy Current Testing

Eddy current testing shall be performed on chillers on a bi-annual basis. During this test, inspect the chiller rupture disk for integrity.

Variable Speed/Frequency Drives

All Variable Speed/Frequency Drives (VSDs) must comply with IEEE 519 for total harmonic distortion and provide a power factor greater than 0.98. Install VFDs on all chiller equipment during upgrade or lifecycle replacement projects to increase unit efficiency.

Portable/Emergency Chiller Hookups

Provide a permanently installed chiller system pipe manifold to a logical exterior location for use in hooking up portable/emergency chiller units. Provide an appropriate permanent hardwired electrical hookup for the portable/emergency chiller. This hookup will allow temporary installation of portable air-cooled chiller to stand in for the existing permanent chillers should there be a need to maintain or replace the permanent chillers.

23 65 00 Cooling Towers

Cooling Towers

Cooling Towers shall conform to NFPA 214, Water Cooling Towers. Condenser Water Towers Condenser water towers will be sized for staging in the same manner as the chillers (minimum N+1 staging, not defining overall system redundancy). Condenser water towers will have water level indicators that are readily visible from the outside and also water level indicators on system control panels.

Filters and Meters

Condenser water systems will have strainers/filters in line and be clearly marked as such. Condenser water systems will incorporate flow rate metering and appropriate alarms.

23 80 00 DECENTRALIZED HVAC EQUIPMENT

23 81 00 Decentralized Unitary HVAC Equipment

23 81 13 Packaged Terminal Air Conditioners

23 81 16 Room Air Conditioners

23 81 19 Self-Contained Air Conditioners

23 81 19.13 Small-Capacity Self-Contained Air Conditioners

23 81 19.16 Large-Capacity Self-Contained Air Conditioners

23 81 23 Computer Room Air Conditioners (CRAC Units)

Self-contained, computer room air conditioning units (CRACs) shall be installed on the access floor to properly control the computer room temperature in legacy datacenters. Liebert FH series or equivalent, as specified in the above document, shall be used as a design basis for the underfloor cooling distribution model.

Room Envelope

The room should be well insulated and must have a sealed vapor barrier. The vapor barrier in the ceiling can be a polyethylene film type. Doors shall not be undercut or have grilles in them. Doors with gaps shall be retrofit with sweep seals or brushes to minimize air exchange. Minimize outside air infiltration into CRAC-supported access floor. Use filtered outside air to maintain maximum 5% of positive pressure in the room.

Installation

CRACs shall be supported from structural flooring (access floor-mounted CRACs are not permitted). Use manufacturer-specified, seismic rated pedestals for support, independent of the access floor. Provide minimum 36-in service access & clearances in front and/or per manufacturer specification at other faces, which ever provides better access.

Waivers for point and row cooling units (ceiling mounted and rack-form factor units may be waived from these installation requirements.

Supply and Return Piping

CRAC unit cooling unit piping shall not interfere with other underfloor equipment distribution. All chilled water piping should be laid outside of operational datacenter zones when possible.

Maintenance.

The absolute minimum maintenance standards for CRAC units are not suitable for DISA operations. The following are minimum standard procedures that are expanded upon in TIM, the Enterprise Operations & Maintenance Management Services Standard (DISA CSI 360-95-3A). Follow guidance in that document to conduct full O&M on CRAC units.

Daily – Exterior check for proper operation. Maintain log of each unit, date or record, temperature & humidity.

Monthly – Interior inspection of belts, humidifier condition. Replace as required.

Quarterly – Inspect/replace filters.

Annually – Recalibrate temperature & humidity & dirty filter sensors.

Humidity settings are only for units that have humidification controls, where a central humidification system has not yet been installed at the datacenter (see section 23 84 00). Where central humidification is available, do not use CRAC-based humidification.

23 81 26 Split-System Air-Conditioners

23 84 00 Humidity Control Equipment

Datacenter humidity control equipment is required to be stand-alone and redundant.

Humidity control through reheat on CRAC units is only permitted on legacy equipment while stand-alone humidity control systems are installed. Requirements for datacenter environment humidity are listed in section 23 30 00.

23 84 13 Humidifiers

Stand-alone ultrasonic humidifiers shall be used in DISA datacenter facilities. These units are cleaner, control humidity more effectively, and are significantly more energy efficient than other types of systems.

Use stainless steel or plastic piping to supply water to the humidifiers. Copper pipe water distribution is prohibited. Use a reverse osmosis system to completely purify the water supply to the humidifiers. Do not use chemically treated water.

23 84 16 Dehumidifiers image2.png image3.jpeg image4.jpeg image4.png image5.png image1.jpeg