Carrier 16JB - Manual (Page 7)

VALVE SIZING — The hot water capacity control
valve CV2, should be sized to handle full design
flow on machine sizes 010-068. Valves CV2 and
CVS on machine sizes 077-124 are each sized at
one-half design flow. The pressure drop and sizing
formula used in sizing the valve(s) should be
consistent with valve manufacturer’s recommenda­
tions. The three-way diverting valve should be sized
to handle the design supply of high-temperature
hot water (HTHW) and must be suitable for high
temperature duty.
Methods Other Than Recirculation to lower supply
hot water temperature to acceptable levels (300 F
max) are:
1. A water-to-water heat exchanger
2. A hot water-to-steam converter
Rupture Disc — All 16JB hot water machines are
provided with a rupture disc on the generator shell
for safety reasons. A generator tube failure could
subject the shell to hot water supply working
pressure.
RELIEF PIPING — Some apphcations have relief
piping installed from the rupture disc discharge to
a location where high-temperature steam and
lithium bromide will not cause damage or injury.
Relief piping must include access to the rupture
disc, allowing replacement in case of failure. Piping
must be supported independent of the machine.
Hot Water Inlet Pressure — It is necessary to ensure
that generator hot water pressure is higher than
saturation pressure corresponding to the inlet hot
water temperature.
Minimum pressures are approximately equal to
10 psi plus the saturation pressure corresponding
to inlet water temperature. Using a recommended
minimum pressure will ensure that hot water inlet
pressure drops will not cause the pressure in the
lines to drop below saturation pressure. This could
cause flashing and water hammer.
CONDENSING WATER TEMP CONTROL
If the absorption machine is to be applied
under conditions where the condensing water
temperature can fall below 55 F, condensing water
temperature control is required. This can be
accomplished by:
1. Fan Cycling — On a single-cell coohng tower,
the tower fan can be shut off when the
temperature of the water reaches 55 F. This
allows the temperature of the tower water to
warm up using the heat rejected from the
machine. In order to ensure against rapid fan
cycling, which can cause fan motor problems, it
is recommended that the cooling tower water
temperature be allowed to rise to design
temperature before fan operation is resumed.
2. Multiple-Cell Tower — The temperature of a
multiple-cell tower can be controlled by
shutting off the number of operating cells. This
creates an effect similar to shutting the fan off
in a single-cell tower. The controls should be
adjusted to shut off in stages to 55 F and come
on again in predetermined stages.
3. Winter Operation — If the absorption machine
is to be applied under winter operating
conditions, an indoor cooling tower sump
should be provided to protect the cooling tower
water from freezing.
GENERAL INFORMATION
Insulation — Machine cold surfaces, subject to
sweating and corrosion, are factory insulated.
Refer to Fig. 8 and Table 2 for details.
d> 6 é
¡S3 FACTORY INSULATION
LEGEND
1 — Refrigeract Pump Housing
2 — EvaporaTor Shell
3 — Refrigerant Suction Piping
Fig. 8 — Machine Cold Surfaces
Table 2 — Insulation For Cold Surfaces
UNIT
16JB
EVAP
SHELL
(ft2)
REFRIG
PUMP(S)
(ft 2)
REFRIG
Suction
(ft2)
LINES
2 in.
Disch
COOLER
WATER BOXES
AND COVERS*
(ft2)
TTlff“
012
014 75 3 6 10 ft 9
018
021
96 3 6 11 ft 12
024
028
114 3 6 12 ft 15
032
036
147 3 6 12 ft 17
041
047
177 4 6 12 ft 20
“054~
057
188 4 9 15 ft 21
061
068
216 4 10 13 ft 24
w
084
275 8 16 48 ft 21
097
107
328 8 17 60 ft 24
115
124
360 8 19 60 ft 27
^Quantity of insulation specified is adequate to cover cooler water
boxes and covers on both ends of machine