Expand Flexibility of Cabinet Coolers with Side Mount Kits

Last week I wrote about the Thermostat Options for Smart Cooling utilizing the EXAIR Cabinet Cooler Systems.  You can see read that blog post here.  Today we will touch base on the Side Mount Kits as an option to expand the flexibility for the installation and operation.

Sometimes there isn’t room above an electrical panel to fit the Cabinet Cooler, even though it takes just 5″ to 7.25″ of space above. In these cases, the Side Mount Kit is available to handle any of the Cabinet Cooler sizes and NEMA ratings. EXAIR offers (6) models of Side Mount Kits –

  • Model 4909 – For NEMA 12 Cabinet Coolers up to 550 BTU.hr (139 Kcal/hr), Aluminum construction
  • Model 4910 – For NEMA 12 Cabinet Coolers , 650 BTU//hr (165 Kcal/hr) and higher, Aluminum construction
  • Model 4906 – For NEMA 4 and 4X Cabinet Coolers up to 550 BTU/hr (139 Kcal/hr), Type 303 Stainless Steel
  • Model 4907 – For NEMA 4 and 4X Cabinet Coolers, 650 BTU/hr (165 Kcal/hr) and higher, Type 303 Stainless Steel
  • Model 4906-316 – For NEMA 4 and 4X Cabinet Coolers up to 550 BTU/hr (139 Kcal/hr), Type 316 Stainless Steel
  • Model 4907-316 – For NEMA 4 and 4X Cabinet Coolers, 650 BTU/hr (165 Kcal/hr) and higher, Type 316 Stainless Steel

side_mounts_new

The NEMA 4 and 4X Cabinet Coolers must be mounted vertically for the unit to properly resist the ingress of liquids and maintain the integrity of the cabinet NEMA rating.

The Side Mount Kits install into a standard electrical knockout (1-1/2 NPS) for easy installation.

If you have any questions about the Side Mount Kits, Cabinet Coolers and/or Thermostat Options or any of the EXAIR Intelligent Compressed Air® Products, feel free to contact EXAIR and myself or one of our Application Engineers can help you determine the best solution.

Brian Bergmann
Application Engineer

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EXAIR Cabinet Cooler System for Electrical Enclosure Cooling

If you watched the Webinar we hosted recently (if not, Watch It here) then you know that the EXAIR Cabinet Cooler System is an intelligent solution for electrical enclosure cooling.  The use of a Thermostat Control system is a key component to a system that provides the needed cooling while keeping compressed air usage to a minimum. There are several choices available, and I will cover those for you today.

The thermostat control systems are the most effective way to operate a Cabinet Cooler. They work by activating the the cooler only when the internal temperature of the enclosure reaches a preset, critical level. Thermostat controlled cooler systems are the best option when a cabinet will experience fluctuating heat loads, caused by operational, environmental, and seasonal changes.

Cabinet Cooler Systems that are ordered from the factory with thermostat control include a solenoid valve and thermostat.  The solenoid valve is available in 110-120VAC, 50/60 Hz, 240VAC, 50/60 Hz, and 24VDC and is UL Listed and CE and RoHS compliant. The thermostat is rated for 24V-240V AC or DC, 50/60 Hz and is UL Recognized and CSA Certified.

Solenoids
Solenoid Valves – 24 VDC, 110 VAC, and 240 VAC Available

 

The thermostat is factory set at 95°F (35°C). It will typically hold an internal cabinet temperature to +/- 2°F (1°C). The thermostat can be adjusted up or down if a different internal temperature is desired by turning the slotted temperature adjusting sleeve, with a 1/16 turn being approximately a 5°F change.

9017_thermoPRINT
Thermostat

 

The solenoid and thermostat components are rated to match and maintain the Cabinet Cooler System and cabinet NEMA rating, and can be NEMA 12, NEMA 4 or NEMA 4X. A Thermostat Control can be added to an existing Continuous Operation Cabinet Cooler System, please consult the factory for help in selecting the right kit.

4825SS
NEMA Type 4X Cabinet Cooler System, which includes the Solenoid Valve and Thermostat

If you have any questions about the Cabinet Coolers and Thermostat Options or any of the EXAIR Intelligent Compressed Air® Products, feel free to contact EXAIR and myself or one of our Application Engineers can help you determine the best solution.

Brian Bergmann
Application Engineer

Send me an email
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Twitter: @EXAIR_BB

Video Blog: Medium Vortex Tube Cooling Kit

EXAIR offers (3) Vortex Tube Cooling Kits, and the video below will provide an overview of the medium size offering, for refrigeration up to 2800 BTU/hr (706 Kcal/hr.)

If you have questions regarding Vortex Tube Cooling Kits or any EXAIR Intelligent Compressed Air® Product, feel free to contact EXAIR and myself or one of our Application Engineers can help you determine the best solution.

Brian Bergmann
Application Engineer

Send me an email
Find us on the Web
Like us on Facebook
Twitter: @EXAIR_BB

Wearing Out Your Sole

3925 Adjustable Spot Cooler
3925 Adjustable Spot Cooler

A shoe manufacturer had a special abrasion test that was required by his customer to test special rubber compounds. The set up was to run a small chain across the bottom of the rubber sole.  The chain was looped to continuously rub against the sole of the shoe.  As they began their wear testing, they noticed that the chain was getting hot from the friction.  The heat would get high enough to change the composition of the rubber and cause a premature failure.  To properly test for wear, they needed to cool the chain.

As they discussed their application with me, they required the chain to be at a specific temperature. I suggested the model 3925 Adjustable Spot Cooler System.  This system comes with a dual point hose kit, a magnetic base, a filter separator, and two additional generators.  The generators of the Adjustable Spot Cooler are a piece which controls the total volume of air through the cooler. They can be switched in and out to produce more or less cooling capacity of the Adjustable Spot Cooler. The main concern was to keep the chain temperature constant.  With a temperature control knob and the additional generators, they could dial in the cooling capacity to keep the chain at the desired temperature.  If the chain was too cold, the sole would not wear properly, and if the chain was too hot, it would change the composition of the rubber material.

They mounted the Adjustable Spot Cooler to the abrasion machine with the dual points blowing on each side of the chain. They quickly noticed that they could keep the chain cooler than the specified temperature.  As a trial, they replaced the generator to the 30 SCFM (850 SLPM) flow rate.  This increased the cooling capacity of the Spot Cooler.  With the higher cooling capacity, they could increase the speed of the abrasion machine to shorten the failure cycle.  This was a great benefit to have as they were testing different rubber compounds to determine the best product; a pronounced advantage in research and development.

If you find out that heat is causing problems in your application, you can contact an Application Engineer at EXAIR for help in finding the correct cooling product. In this instance, friction was the culprit and the Adjustable Spot Cooler was the solution.

John Ball
Application Engineer
Email: johnball@exair.com
Twitter: @EXAIR_jb

The Effect of Back Pressure on a Vortex Tube Part 2, Calculating Btu/Hr.

My previous blog post was about how Vortex Tubes react when there is back pressure due to a restriction on either the hot or cold discharge of the Vortex Tube.  In it I mentioned that there is a formula to calculate what the cooling capacity (Btu/Hr) will be if there is no way to avoid operating the Vortex Tube without back pressure on the discharge. That is the calculation focus of this blog – calculating Btu/hr of a Vortex Tube with back pressure.

To continue with the same example, the calculations from the previous blog are shown below.  Last time the example Vortex Tube was operating at 100 psig inlet pressure, 50% cold fraction, and 10 psi of back pressure. We will need some additional information to determine the Btu/Hr capacity. The additional information needed is the temperature of the supplied compressed air as well as the ambient air temperature desired to maintain.  For the example the inlet compressed air will be 70°F and desired ambient air temperature to maintain will be 90°F.

(100 psig + 14.7 psia) / (10 psig + 14.7 psia) = X / 14.7 psia
4.6437 = X / 14.7
X= 14.7 * 4.6437
X = 68.2628
(Values have been rounded for display purposes)

The calculation above gives the compensated operating pressure (X = 68.2628) which will be needed for the BTU/hr calculation. The rated air consumption value of the Vortex Tube will also need to be known.  A 30 SCFM rated generator will be used for this example, the normal BTU capacity of a Vortex Tube with a 30 SCFM generator is 2,000 BTU/hr.

First, determine the new consumption rate by establishing a ratio of the compensated pressure (68.2628 psi) against the rated pressure (100 psi) at absolute conditions (14.7 psia).

(68.2628 PSIG + 14.7 (atmospheric pressure)) / (100 PSIG (rated pressure) + 14.7) = .7233
.7233 x 30 SCFM  = 21.7 SCFM Input 

Second, the volumetric flow of cold air at the previously mentioned cold fraction (50%) will be calculated.  To do this multiply the cold fraction setting (50%) of the Vortex Tube by the compensated input consumption (21.7 SCFM) of the Vortex Tube.

50% cold fraction x 21.7 SCFM input = 10.85 SCFM of cold air flow

Third, the temperature of air that will be produced by the Vortex Tube will need to be calculated.  For this consult the Vortex Tube performance chart which is shown below. To simplify the example the compensated operating pressure (68.2628 psi) will be rounded to 70 psig and to obtain the 70 psig value the mean between 80 psig and 60 psig performance from the chart will be used.

Cold Fraction
EXAIR Vortex Tube Performance Chart

For the example: A 70 psig inlet pressure at 50% cold fraction will produce approximately an 88°F drop.
Fourth, subtract the temperature drop (88°F) from the temperature of the supplied compressed air temperature (70°F).

70°F Supply air – 88°F drop = -18°F Output Air Temperature

Fifth,  determine the difference between the temperature of the air being produced by the Vortex Tube (-18°F) and the ambient air temperature that is desired (90°F).

90°F ambient – -18°F air generated = 108°F difference.

The sixth and final step in the calculation is to apply the answers obtained above into a refrigeration formula to calculate BTU/hr.

1.0746 (BTU/hr. constant for air) x 10.85 SCFM of cold air flow x 108°F ΔT = 1,259 BTU/hr.

In summary, if a 2,000 BTU/hr. Vortex tube is operated at 100 psig inlet pressure, 50% cold fraction, 70°F inlet air to maintain a 90°F ambient condition with 10 psi of back pressure on the outlets of the Vortex Tube the cooling capacity will be de-rated to 1,259 BTU/hr.  That is a 37% reduction in performance.  If a back pressure cannot be avoided and the cooling capacity needed is known then it is possible to compensate and ensure the cooling capacity can still be achieved.  The ideal scenario for a Vortex Tube to remain at optimal performance is to operate with no back pressure on the cold or hot outlet.

Brian Farno
Application Engineer Manager
BrianFarno@EXAIR.com
@EXAIR_BF

The Effect of Back Pressure on a Vortex Tube

Vortex tubes have been considered a phenomena of Physics and boggled minds for many years.  To give a brief run down of how the Vortex Tube works please refer to Figure 1 below.

How_A_Vortex_Tube_Works
Figure 1

As seen above, the control valve is determining the amount of air allowed to escape the hot end and sets the cold fraction.  A cold fraction is the percentage of air that exits the cold side versus the hot side. The cold fraction and operating pressure sets the temperature drop on the cold end and temperature rise on the hot end, as well as volumetric flow out of both ends. The control valve is not the only variable that can alter the cold fraction of the Vortex Tube though.

In Figure 1 and the performance chart below, there is no restriction on the hot end or the cold end outlets. No restriction means no back pressure and the cold air has the easiest path to the area needing cooling. Back pressure can directly affect the performance of a Vortex Tube.  As little as 3 psig of back pressure can begin to alter the temperature drop or rise on the Vortex Tube.  This is due to the fact that Vortex Tubes operate off an absolute pressure differential.  If the outlets have a restriction on them then they are not discharging at atmospheric pressure, 14.7 psi. What kind of items can cause back pressure and can the performance with a back pressure on the outlet be determined?

Back pressure is created by implementing any form of restriction on the hot or cold outlet. This may be undersized tubing to deliver the cold air or a valve that has been installed to try and control the volume of air being blown onto the process as well as many other possibilities.  The best rule of thumb to eliminate back pressure is to keep the tubing on an outlet the same cross sectional dimension as the outlet on the Vortex Tube and try to keep the tubing as short as possible.

If back pressure cannot be prevented, the performance variance of the Vortex Tube can be calculated and possibly compensated for. The variables that are needed to do so are the inlet air pressure of the vortex tube and the amount of back pressure that is being seen on the outlets. If this is different from the hot end to the cold end both will need to be known.  If these are not known they can be measure by installing a pipe Tee and a pressure gauge. This may need to be a sensitive pressure gauge that measures even relatively low psig. (1-15 psig)

Once these variables are known, we want to look at an absolute pressure differential versus the back pressure differential. For example, the Vortex Tube is a operating at 100 psig inlet pressure, 50% cold fraction and 10 psi of back pressure.  We look at the pressure differentials and can use Algebraic method to determine the inlet pressure supply that the tube will actually perform at.

(100 psig + 14.7 psia) / (10 psig + 14.7 psia) = X / 14.7 psia
4.6437 = X / 14.7
X= 14.7 * 4.6437
X = 68.2628
(Values have been rounded for display purposes)

So if there is a 10 psig back pressure on the outlet of a Vortex tube operating a 100 psig inlet pressure the tube will actually carry performance as if the inlet pressure was ~68 psig.   To showcase the alteration in performance we will look at just the temperature drop out of the cold side of the Vortex Tube. (Keep in mind this is a drop from the incoming compressed air temperature.)

Vortex Tube Performance Data
Vortex Tube Performance Chart

As shown in the performance chart above, if the Vortex Tube was operating at 100 psig inlet pressure and 50% cold fraction the temperature drop would be 100°F.  By applying a 10 psi back pressure on the outlet of the Vortex Tube the temperature will be decreased to ~87°F temperature drop.   This will also decrease the volumetric flow of air exiting the Vortex Tube which can also be calculated in order to determine the cooling capacity of the Vortex Tube at the altered state.  Keep an eye out for a follow up blog coming soon to see that calculation.

Brian Farno
Application Engineer Manager
BrianFarno@EXAIR.com
@EXAIR_BF