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INSTALLATION - COOLING COIL UNITS
9. Failure to obtain a high vacuum is indicative of a great
deal of moisture or a small leak. Break the vacuum with
a charge of dry nitrogen or other suitable gas and recheck
for leaks (soapy water works well). If no leaks are found,
continue vacuuming the coil until the desired vacuum is
reached.
10. All field piping must be self-supporting.
Chilled Fluid Piping
To prevent noise and coil damage from water hammer, an
air vent is necessary to bleed off the accumulated air in the
system. The vent should be located on the top of the inlet
manifold where the air collects. This vent should be opened
twice a year.
The outlet manifold should have a drain installed on the bottom
to allow for periodic flushing of the system to remove sediments
and corrosion products from the cooling coil. This drain
should be opened to allow some fluid to drain twice a year.
Check coloration and viscosity of the effluent for indications of
corrosion in the system. The lines between the unit and the
structure should be insulated to prevent freezing of the water.
1. Once installed, the coil should be pressurized to 100 psig
with dry nitrogen or other suitable gas. The coil should be
left pressurized for a minimum of 10 minutes. If the coil
holds the pressure, the hook-up can be considered leak
free. If the pressure drops by 5 psig or less re-pressurize
the coil and wait another 10 minutes. If the pressure drops
again, there is more than likely one or more small leaks
which should be located and repaired. Pressure losses
greater than 5 psig would indicate a larger leak that should
be isolated and repaired.
2. All field brazing and welding should be performed using
high quality materials and an inert gas purge (such as
nitrogen) to reduce oxidation of the internal surface of
the coil.
3. All field piping must be self supporting. System piping
should be flexible enough to allow for thermal expansion
and contraction of the coil.
4. Fill the coil with water with all air vents open so that air is
eliminated from within the coil circuitry and headers. Verify
that all vents and drains are not obstructed and do discharge
a stream of water.
5. Close all vents and perform a hydrostatic leak test
of all brazed, threaded or flanged joints, valves and
interconnecting piping. Recheck the coil level and correct
if necessary. When the setup is found to be leak free,
discharge and discard initial water charge. It is important that
all grease, oil, flux and sealing compounds present from the
installation be removed.
Figure 19.1 - General Chilled Fluid Piping
Air Vent
Vent Plug
Gate Valve
T ee
Dirt Leg
Cap
Table 19.1 - Cooling Coil Performance Limits
Cooling
Model
Min
Type
Size
CFM
75
688 l
100
802 m
125
937
150
1,125
175
1,312
DX
200
1,500
225
1,687
250
1,875
300
2,250
350
2,625
400
3,000
75
609
100
750
125
937
150
1,125
175
1,312
Chilled
200
1,500
Water
225
1,687
250
1,875
300
2,250
350
2,625
400
3,000
j Based on 550 feet per minute (FPM) coil face velocity.
k Based on 95°F/75°F Entering Dry Bulb/Wet Bulb.
l Model Size 75 minimum CFM for DX Dual Circuit is 621.
m Model Size 100 minimum CFM for DX Dual Circuit is 745.
5-594.10
Drain Plug
Union
Single Circuit
Dual Circuit
Max
Area
Max
Area
(ft 2 )
(ft 2 )
CFM j
CFM j
1,891
3.44
1,707
3.10
2,206
4.01
2,048
3.72
2,521
4.58
2,416
4.39
3,352
6.09
3,165
5.76
3,724
6.77
3,538
6.43
5,214
9.48
4,996
9.08
1,676
3.05
n/a
n/a
2,011
3.66
n/a
n/a
2,372
4.31
n/a
n/a
3,214
5.84
n/a
n/a
3,592
6.53
n/a
n/a
5,073
9.22
n/a
n/a
Max
Cooling
(Tons) k
9.4
11.4
13.4
18.1
20.2
27.3
10.6
12.6
14.8
19.3
21.3
29.3
19
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