JOHNSON CONTROLS
39
SECTION 4 – INSTALLATION
FORM 150.27-NM1
ISSUE DATE: 09/30/2015
4
To ensure a solid column of liquid refrigerant to the ex-
pansion valve, the total liquid line pressure drop should
never exceed 40 PSI (276 kPa). Refrigerant vapor in
the liquid line will measurably reduce valve capacity
and poor system performance can be expected.
To allow adequate oil return to the compressor, dis-
charge risers should be sized for a minimum of 1000
FPM (5.08 m/s) while the system is operating at mini-
mum capacity to ensure oil return up the suction riser.
Chiller Below Condenser
On a system where the chiller is located below the
condenser, the discharge line must be sized for both
pressure drop and oil return. In some cases a double
discharge riser must be installed to ensure reliable oil
return at reduced loads.
Condenser Below Chiller
When the condenser is located below the chiller, the
liquid line must be designed for both friction loss and
static head loss due the vertical rise. The value of static
head loss of 5 PSI/ft. (3.4 kPa/30 cm) must be added
to the friction loss pressure drop in addition to all pres-
sure drops due to driers, valves, etc.
OIL TRAPS
All horizontal discharge lines should be pitched at least
1/4" per foot (2 cm/m) in the direction of the refriger-
ant flow to aid in the return of oil to the chiller. All
discharge lines with a vertical rise exceeding 3 feet (.91
meters) should have a “P” trap at the bottom and top of
the riser. Discharge lines with a vertical rise exceeding
25 feet (7.6 meters) should be trapped every 15 feet
(4.6 meters).
REFRIGERANT CHARGE
The chiller is charged and shipped with a dry nitro-
gen holding charge. The chiller and the remote piping
condenser must be evacuated and the operating charge
for the chiller, remote condenser and refrigerant pip-
ing must be weighed in after all refrigerant piping is
installed, leak checked, and evacuated. A minimum of
70% of the calculated complete system charge must be
installed before attempting to operate a system. Final
adjustment of refrigerant charge should be verified by
Subcooling on Page 97 in SECTION 6 – COMMIS-
).
REFRIGERANT PIPING REFERENCE
R-410A Copper Line Sizing
When selecting pipe diameter and material for remote
condenser piping R-410A systems such as used with
YCRL chillers, it is recommended that ASTM B280
material, type “L” or “K” is used. According to ASME
Standard B31.5-2006 (table 502.3.1), ASTM B280
copper does not require a derate when brazed. By com-
parison, ASTM B88 material does take an annealing
penalty when brazing, which, in some applications,
could reduce the calculated yield strength to a level be-
low the system design.
YCRL Line Sizing Notes
The YCRL chiller has a maximum design working
pressure of 560 psig, a mechanical high pressure cutout
to shut the unit off at 585 psig, and (the unit) is rated at
650 psig. The maximum discharge pipe diameter used
on YCRL is 2-1/8".
ASTM B280, type “L” pipe, 2-1/8" diameter has a
pressure rating of 608 psi per ASME B31.5-2006 sec-
tion 504.1.2, with an additional 20% increase allowed
in section 502.2.3 “Ratings: Allowance for Variations
from Normal Operation” for a maximum allowable
pressure of 730 psi.
Type “K” pipe (thicker wall), per ASME B31.5-2006
section 504.1.2, has a rating of 725 psi before the ad-
ditional 20% allowance is taken.
For more details, refer to
“ASHRAE Refrigeration
Handbook, Chapter 2”, “Tables 2 and 3” in this IOM
and YORK DX Piping Guide “Form 050.40-ES2”
1. Table capacities are in tons of refrigeration.
∆p = Pressure drop due to line friction, PSI per
100 feet equivalent length.
∆t = Change in saturation temperature corre
-
sponding to pressure drop, °F per 100 feet.
2.
Line capacity for other saturation temperatures ∆t
and equivalent lengths.
Actual ∆t
Table ∆t
X
(
(
Table L
e
Actual L
e
(
(
0.55
Line Capacity = Table Capacity X
3.
Saturation temperature ∆t (for other capacities
and equivalent lengths L
e
Actual Capacity
Table Capacity
X
(
Actual L
e
Table L
e
(
1.8
∆t = Table ∆t X
