Emerson Liebert Xtreme Density Specifikace stáhnout pdf (Strana 23)

Designing a Liebert XD Solution

3.9 Liebert XD Coolant™

The coolant used in the XD system is HFC-134a (1,1,1,2-tetrafluoroethane), made by a number of

manufacturers. The amount of coolant used by the XD system may be significantly higher than typi-

cal DX cooling systems.

All the major components of an XD system must be installed in a space with a volume of at least

1,000 ft

(28.3m

) for each 16 pounds of coolant in that system from Table 1, ASHRAE Standard 15-

2001, Safety Standard for Refrigeration Systems. If the XDP/XDC is placed in a separate area, such as

a machine room, then this area must also meet the volume requirement. Inside the critical space, this

includes the space under the raised floor, and the space between the top of the raised floor and the

bottom of a suspended ceiling. If the suspended ceiling is all open grates, then this additional space,

up to the overhead deck, would also be included.

Example

A space is 5,000 square feet, with an 18" raised floor and an 8' 6" suspended ceiling. XDOs and an

XDP are to be placed in this raised floor area.

The volume of the space is (1.5 + 8.5) x 5,000 or 50,000 cubic feet.

The maximum amount of R-134a coolant that can be used in a single XDP/XDC/XDO/XDV system

within this space is 16 * (50000/1000) = 16 * 50 = 800 lb.

Multiple XD systems can be installed in this space, as long as the amount of R-134a coolant in any

one system does not exceed 800 lb.

3.10 Liebert XD Piping System Design

All piping must be ASTM (American Society for Testing and Materials) Type L copper pipe. The typi-

cal maximum operating pressure in the system is 90 psi (620kPa).

Piping for the XD system is arranged in a manner similar to piping for a chilled water system. XDOs

or XDVs are connected in parallel between main return and supply pipes going to and from the XDP/

XDC. Figure 18 represents a typical configuration. The guidelines provided for pipe size must

be strictly followed. Failure to size the main lines and connection lines adequately may

result in reduced cooling capacity. The critical aspects of pipe sizing are related to coolant vol-

ume and pressure drop. Both must be minimized.

Figure 18 Piping for XDP/XDC used with XDO or XDV units

CAUTION

The XD pumped R-134a refrigerant circuits do not use refrigerant oil.

Do NOT put oil in the R-134a system.

NOTE

Local codes might permit exceeding the maximum refrigerant limit stated above if refrigerant

detector and an exhaust system are installed. As an alternative, oxygen sensors may be

installed to meet some local codes.

SLOPE—The main supply and return lines to and from the XDP/XDC must be

sloped downward toward the XDP/XDC at a rate of 1" per 20 feet (25mm per 6m) of

pipe run. Horizontal connector lines should also be sloped downward from the

cooling modules toward the main supply and return lines.

XDP/

XDC

XDO/XDV XDO/XDV XDO/XDV XDO/XDV XDO/XDV

1 2 ... 18 19 20 21 22 23 24 25 26 27 28 ... 51 52

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