line is sufficient to move oil along with gas to the compressor. Where
equipment location requires vertical risers, line shall be sized to
maintain sufficient velocity to lift oil at minimum system loading and
corresponding reduction of gas volume. Install a double riser when excess
velocity and pressure drop would result from full system loading. Larger
riser shall have a trap, of minimum volume, obtained by use of 90- and
45-degree ells. Arrange small riser with inlet close to bottom of
horizontal line, and connect to top of upper horizontal line. Do not
install valves in risers.
3.2.4
Refrigerant Driers, Sight Glass Indicators, and Strainers
Provide refrigerant driers, sight glass liquid indicators, and strainers in
refrigerant piping in accordance with [FS OO-A-373] [FS OO-A-374] [FS
A-A-50502] when not furnished by the manufacturer as part of the equipment.
Install driers in liquid line with service valves and valved bypass line
the same size as liquid line in which dryer is installed. Size of driers
shall be determined by piping and installation of the unit on location.
Install dryers of 820 mL 50 cubic inches and larger vertically with the
cover for removing cartridge at the bottom. Install moisture indicators in
the liquid line downstream of the drier. Indicator connections shall be
the same size as the liquid line in which it is installed.
3.2.5
Strainer Locations and Installation
Locate strainers close to equipment they are to protect. Provide a
strainer in common refrigerant liquid supply to two or more thermal valves
in parallel when each thermal valve has a built-in strainer. Install
strainers with screen down and in direction of flow as indicated on
strainer's body.
3.2.6
Solenoid Valve Installation
Install solenoid valves in horizontal lines with stem vertical and with
flow in direction indicated on valve. If not incorporated as integral part
of the valve, provide a strainer upstream of the solenoid valve. Provide
service valves upstream of the solenoid valve, upstream of the strainer,
and downstream of the solenoid valve. Remove the internal parts of the
solenoid valve when brazing the valve.
3.3
AUXILIARY DRAIN PANS, DRAIN CONNECTIONS, AND DRAIN LINES
Provide auxiliary drain pans under units located above finished ceilings or
over mechanical or electrical equipment where condensate overflow will
cause damage to ceilings, piping, and equipment below. Provide separate
drain lines for the unit drain and auxiliary drain pans. Trap drain pans
from the bottom to ensure complete pan drainage. Provide drain lines full
size of drain opening. Traps and piping to drainage disposal points shall
conform to Section 15400 PLUMBING SYSTEMS.
3.4
ACCESS PANELS
Provide access panels for concealed valves, controls, dampers, and other
fittings requiring inspection and maintenance.
3.5
AIR FILTERS
Allow access space for servicing filters.
Install filters with suitable
sealing to prevent bypassing of air.
SECTION 15730N
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