|
Cabinet
Cooler Selection
|
Selecting the
Right Cabinet Cooler
EXAIR
Cabinet Coolers are available with or without thermostat
control. The continuous coolers (Model 4200 and 4700 series)
are recommended when constant cooling and a constant positive
purge are desirable. The thermostatically controlled systems
(Model 4300 and 4800 series) save air by activating the
cooler only when internal temperatures approach critical
levels. The adjustable thermostat is factory set at 95°F
(35°C). Thermostatic systems are recommended where heat
load fluctuates and continual purge is not required.
All
EXAIR Cabinet Cooler Systems contain a 5 micron Automatic
Drain Filter for the compressed air supply and a Cold Air
Distribution Kit to circulate the cold air throughout the
enclosure.
| Special
Cabinet Coolers |
|
| EXAIR
manufactures special NEMA 4, 4X and 12 Cabinet Coolers
suited to specific environmental requirements: |
High
Temperature Cabinet Coolers
for
ambients of 125° to 200°F (52° to 93°C) are available.
Internal components can withstand high temperatures
(like those near furnaces, ovens, etc.). |
|
 |
Non-Hazardous
Purge
Cabinet Cooler
are ideal for dirty areas where contaminants
might normally pass through small holes or conduits.
Under normal conditions the NHP Cabinet Cooler System
provides a slight positive pressure in the enclosure
by passing 1 SCFM (28 SLPM) of air through the cooler.
When the thermostat detects high temperature, it
energizes the solenoid valve to pass full line pressure
to the Cabinet Cooler, giving it full cooling capability.
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| |
| Cabinet
Cooler Systems with a 2800 Btu/hr. (706 Kcal/hr.) capacity
are available. They are ideal for applications
where the heat load is extremely high.
If
you have special requirements, please contact an Application
Engineer to discuss the application.
Environmental
Considerations
NEMA
12 Cabinet
Coolers (dust-tight, oil-tight) are ideal for general
industrial environments where no liquids or corrosives
are present.
NEMA
4 Cabinet Coolers (dust-tight,
oil-tight, splash resistant, indoor/outdoor service)
incorporate a low pressure relief valve for both the
vortex tube and cabinet air exhaust. This valve closes
and seals when the cooler is not operating, to
maintain the integrity of a NEMA 4 enclosure.
NEMA
4X Cabinet Coolers offer the same protection
as NEMA 4, but is constructed of 304 stainless
steel for service in corrosive environments.
|
|
Specifications
| Cabinet
Cooler Specifications |
NEMA
12
(Dust, oil resistant) |
Model
# |
Capacity
Btu/hr. |
Capacity
Kcal/hr. |
Thermostat
Control |
| 4208 |
550 |
139 |
No |
| 4225 |
1700 |
428 |
No |
| 4230 |
2000 |
504 |
No |
| 4308 |
550 |
139 |
Yes |
| 4325 |
1700 |
428 |
Yes |
| 4330 |
2000 |
504 |
Yes |
NEMA
4
(Splash resistant) |
4708 |
550 |
139 |
No |
| 4725 |
1700 |
428 |
No |
| 4730 |
2000 |
504 |
No |
| 4808 |
550 |
139 |
Yes |
| 4825 |
1700 |
428 |
Yes |
| 4830 |
2000 |
504 |
Yes |
NEMA
4X
(Corrosion resistant) |
4708SS |
550 |
139 |
No |
| 4725SS |
1700 |
428 |
No |
| 4730SS |
2000 |
504
|
No |
| 4808SS |
550 |
139
|
Yes |
| 4825SS |
1700 |
428
|
Yes |
| 4830SS |
2000 |
504
|
Yes |
|
| |
How to Calculate Heat Load for your Enclosure
| To
determine the correct model for your application, it
is first necessary to determine the total heat load
to which the control panel is subjected. This total
heat load is the combination of two factors — heat
dissipated within the enclosure and heat transfer from
outside into the enclosure.
To
Calculate Btu/hr.
- First,
determine the approximate watts of heat generated
within the enclosure. Watts x 3.41 = Btu/hr.
- Then,
calculate outside heat transfer as follows:
| a. |
Determine
the area in square feet exposed to the air,
ignoring the top of the cabinet. |
| b. |
Determine
the temperature differential between maximum
surrounding temperature and desired internal
temperature. Then, using the Temperature Conversion
Table (below), determine the Btu/hr./ft.2
for that differential. Multiplying the cabinet
surface area times Btu/hr./ft.2
provides external heat transfer in Btu/hr. |
- Add
internal and external heat loads for total heat
load.
|
| Temperature
Conversion Table |
Temperature
Differential °F |
Btu/hr./ft2 |
| 5 |
1.5 |
| 10 |
3.3 |
| 15 |
5.1 |
| 20 |
7.1 |
| 25 |
9.1 |
| 30 |
11.3 |
| 35 |
13.8 |
| 40 |
16.2 |
|
Example:
|
Internal
heat dissipation: 471 Watts or 1606 Btu/hr.
|
|
Cabinet
area: 40 ft.2
|
|
Maximum
outside temperature: 110°F
|
|
Desired
internal temperature: 95°F
|
The
conversion table (above) shows that a 15°F temperature
differential inputs 5.1 Btu/hr./ft.2
40
sq. ft. x 5.1 Btu/hr./ft.2 = 204 Btu/hr.
external heat load.
Therefore,
204 Btu/hr. external heat load plus 1606 Btu/hr. internal
heat load = 1810 Btu/hr. total heat load or Btu/hr.
refrigeration required to maintain desired temperature.
In
this example, the correct choice is a 2000 Btu/hr.
Cabinet Cooler System. Choose a Cabinet Cooler model
by determining the NEMA rating of the enclosure (type
of environment), and with or without thermostat control.
|
| |
|
Need
Help Sizing EXAIR Cabinet Coolers?
Fill
out our online Cabinet
Cooler Sizing Guide Form and we'll
contact you with our recommendation right away
- OR
-
For
answers NOW, call our Tech Sales at (416) 410-1313
|
| |
To
Calculate Kcal/hr.
- First,
determine the approximate watts of heat generated
within the enclosure. Watts x .86 = Kcal/hr.
- Then,
calculate outside heat transfer as follows:
| a. |
Determine
the area in square meters exposed to the air,
ignoring the top of the cabinet. |
| b. |
Determine
the temperature differential between maximum
surrounding temperature and desired internal
temperature. Then, using the Metric Temperature
Conversion Table (below), determine the Kcal/hr./m2
for that differential. Multiplying the cabinet
surface area times Kcal/hr./m2
provides external heat transfer in Kcal/hr. |
- Add
internal and external heat loads for total heat
load.
|
Temperature
Conversion Table
(METRIC) |
Temperature
Differential °C |
Kcal/hr./m2 |
| 3 |
4.5 |
| 6 |
9.7 |
| 9 |
15.1 |
| 12 |
21 |
| 15 |
27 |
| 18 |
34 |
| 21 |
41 |
|
Example:
|
Internal
heat dissipation: 471 Watts or 405 Kcal/hr.
|
|
Cabinet
area: 3.7m2
|
|
Maximum
outside temperature: 44°C
|
|
Desired
internal temperature: 35°C
|
The
conversion table (above) shows that a 9°C temperature
differential inputs 15.1 Kcal/hr./m 2 .
3.7m
2 x 15.1 Kcal/hr./m 2 =56 Kcal/hr. external heat load.
Therefore,
56 Kcal/hr. external heat load plus 405 Kcal/hr. internal
heat load = 461 Kcal/hr. total heat load or Kcal/hr.
refrigeration required to maintain desired temperature.
In
this example, the correct choice is a 504 Kcal/hr.
Cabinet Cooler System. Choose a Cabinet Cooler model
by determining the NEMA rating of the enclosure (type
of environment), and with or without thermostat control.
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| |
| Dimensions
|
| |
|
|
NEMA
4, 4X and 12 Cabinet Coolers are available in many
cooling capacities for
large and small control panels. |
|
|
Other
Factors
|
Filtration:
EXAlR
Cabinet Cooler Systems include a 5 micron automatic
drain water and dirt filter. This filter is critical
for protection of electronics from water in
the compressed air line. If oil is present in the
compressed air supply, the addition of a coalescing
(oil removal) filter, such as EXAlR Model 9005,
is recommended.
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|
|
|
Systems
for continuous operation include a Cabinet Cooler,
distribution kit and filter.
|
|
 |
Cold
Air Distribution Kit:
The
kit includes a length of flexible vinyl tubing used
to direct the cold air for circulation, or to hot
spots. Tubing connectors and adhesive backed clips
to hold the tubing in place are provided. |
Humidity:
For
a continuous operating Cabinet Cooler, relative humidity
inside the enclosure stabilizes at 45%. No moisture
condenses inside the enclosure. (The enclosure must
be sealed to prevent condensation.) |
Inlet
Air Temperature:
Cabinet
Cooler Systems provide a 50°F (28°C) temperature drop
from supply air temperature when the inlet pressure
is 100 PSlG (6.9 BAR). Elevated inlet temperature will
produce a corresponding rise in cold air temperature
and reduction in cooling capacity. Low air pressures
will also reduce the cooling capacity. |
Mounting:
The
Cabinet Cooler mounts to the enclosure through a drilled
hole or electrical knockout. The NEMA 12 Cabinet Coolers
may be mounted on the top or side of the panel. NEMA
4 and 4X Cabinet Coolers must be mounted on the
top of the panel. |
 |
Solenoid
Valve and Thermostat:
Cabinet
Cooler Systems with thermostat control include a solenoid
valve and thermostat that limit the flow of compressed
air to only when cooling is needed. The solenoid valve
is rated 120V, 60 Hz or 110V, 50 Hz. It is UL Listed,
CSA Certified. |
The
thermostat is factory set at 95°F
(35°C). It will normally hold ±2°F
(1°C) inside the cabinet. It is rated 120V, 50/60
Hz and is UL Recognized, CSA Certified. |
|
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