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Table 28 — Booster Compressor Starting Data
*Based on 1750 rpm with 5F,H compressors. Will vary directly with rpm at other speeds.
CONDENSERS
Condenser Physical Data —
Refer to Table 29. Re-
fer to 5F,H Product Data for information on the current
P701 water-cooled condensers used with the 5F,H water-
cooled condensing units.
Condenser Selection Considerations —
On most
installations the condenser is selected within recommended
conditions specified in ARI Standards. Main consider-
ations are:
1. The water velocity is within a range of 1 to 12 ft per
second (to minimize corrosion and erosion).
2. It is good practice to select condensers on a leaving tem-
perature difference between 6 and 12 degrees. In general,
higher temperature differences are used only where con-
densing water temperature is quite low or where special
conditions make it economical to do so. A high tempera-
ture difference not only makes effect of fouling more
pronounced but since the condenser volume is likely to be
small, the effect on noncondensable gases will be greater.
Table 30 lists maximum water velocities from Carrier
System Design Manual. Limits are above ARI recommended
values but are generally accepted where ARI conformance is
not specified. See Part 5 of the Carrier System Design Manual
for further details.
Table 31 lists condenser water quantities (gpm) for water
velocities from 3 to 12 fps. For higher velocities, use formulas
below Table 31.
Condenser Duty —
The capacity of a given compressor
is greatest at high saturated suction temperatures. Because of
this, the compressor normally requires the largest condenser at
these conditions or for air conditioning duty.
On refrigeration or low temperature applications, the same
compressor displacement results in a lower refrigeration
capacity and, consequently, less heat rejection. Thus, con-
denser size is smaller than would normally be required with the
same compressor on air conditioning duty.
Condenser size is also affected by refrigerant used, since
compressor capacities (and thus heat rejection) differ with
Refrigerants 12, 22, and 502.
Pulldown —
Condensers for systems subject to pulldown
periods, especially low temperature or multistage systems,
should be oversized beyond the capacity required at the final
balanced load condition. The condenser must adequately
handle load during the first stages of pulldown, when system
capacity is substantially greater than at final condition.
If pulldown load is sizable, as in most water or brine cooling
applications, check the condenser performance when it is
handling total heat rejection at maximum rated suction temper-
ature (50 F for most compressors). Condenser size and water
quantity must be adequate to handle this start-up load without
resulting in excessive head pressure or excessive water pres-
sure drop. As a rough guide, the selected condenser should
have a maximum total heat rejection rating that is equal to
or greater than the compressor heat rejection at pulldown
conditions.
If this pulldown occurs infrequently, it may be possible to
select a condenser for design conditions and on each start-up
limit compressor capacity by manually throttling suction gas
flow. This can be done by partially closing suction valve but
this will extend time required to reach design conditions.
If the pulldown is of short duration, such as on a direct
expansion coil, suction temperature will drop very rapidly and
more than likely design conditions will be reached before the
compressor would cut out on high pressure. No oversizing of
the condenser would be required.
Whenever possible, the selected condenser should never be
of a larger size than the largest condenser that will match the
compressor used and still be a standard combination. This
should be considered especially when the condensers are to be
used with 5F,H series open reciprocating compressors.
Fouling and Fouling Factors —
Fouling in con-
denser tubes is result of a build-up of scale within tubes
because of impurities in water. As a result, heat transfer is
adversely affected. Fouling factors are a means of identifying
degree of fouling.
Condensers should not be selected for less than 0.0005 foul-
ing factor, even when high quality water is available. For lower
quality water, use larger fouling factors from the condenser
ratings, but temper factor according to operating conditions.
The following affect magnitude of fouling factor selected:
• Percentage of yearly operating time.
• Frequency of tube cleaning.
• Condensing temperature.
• Type of water treatment.
For instance, reduce fouling factor when the operating time
is less than 4000 hours per year, when frequent cleaning of
tubes takes place, or when low condensing temperatures exist.
COMPR
SIZE
UNLOADING
DURING
STARTING
MAX COMPR STARTING TORQUE (lb-ft) RECOMMENDED MIN MOTOR SIZE HP
FRICTION
HP*
(fhp)
R-12 R-22 or R-502 R-12 R-22 or R-502
Saturated Discharge Temperature (F)
High
Torque
Normal
Torque
High
Torque
Normal
Torque
10 F 30 F 10 F 30 F
5F20
None 91315 21— 233.67
5F30
None101516243355.91
5F40
75%812131933551.15
5F60
66
2
/
3
%10151624 3 5 57
1
/
2
1.64
5H40
75%192830 45 57
1
/
2
7
1
/
2
10 2.25
5H46
75%243538 567
1
/
2
10 10 15 2.25
5H60
66
2
/
3
%233437 547
1
/
2
10 10 15 3.07
5H66
66
2
/
3
%294346 68101515203.07
5H80
75%263841 60101520203.82
5H86
75%334851 75152020303.82
5H120
66
2
/
3
%416065 94152020305.25
5H126
66
2
/
3
% 51 75 81 118 20 30 30 40 5.25