Appendix I - CRAC part 1.pdf

CRAC Specifications

APPENDIX I

Excerpt from CSI 360-95-3, Facilities Standards

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. Settings:

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

Parameter Unit Set Point Tolerance (±) High/Low Alarm

Temperature °F 72 2 78/66

Humidity %RH 50 5 65/45

-This specification shall be followed for selection of units to be installed.