fan airflow, in or out of back panel.

[philpridd]

Hello all,I have just fitted a fan out of an arc welder to my Clark en 90. The fan works fine, but it is pulling air into the welder,a friend has a Clark 105 turbo,on which the fan is pushing the air out of the welder. Should I re wire my fan so it is pushing the air out, as on my mates welder, I would have thought it was better to be drawing cool air in than pushing it out,but as the 105 has a fan factory fitted,then I assume that the air should be pushed out.Any advice/comments? Thanks ,Phil.

 

[rtbcomp]

Fans on all the larger computer equipment I've ever worked on blew air in through a filter. This also pressurises the cabinet slightly to help keep dust out. Also by blowing in you can direct the airflow more easily to the parts that get hot.

If it's a two-wire fan you won't be able to reverse it electrically anyway.

 

[philpridd]

fan airflow

Thanks for that,yes it is a 2 wire fan,so I assume it must have been meant to work that way on the arc welder I took it out of,as long as it does the job,I dont care which way it blows,in or out,time will tell, it was suprisingly easy to fit,though only one mounting hole lines up with the original,but to look at it ,you would think it had been factory fitted,probably because it cae out of another welder, Thanks ,Phil.

 

[Tin Can]

The fans in computers are reversible - their is an arrow showing the direction of flow, if their isnt and you connect it up and its blowing the wrong way you simply unscrew it and turn it round. As you said its a fan from another welder it may not have the dual flange fittings that allow the flow to be 'flipped round' - As an aside our gas oven gave up last year and whilst it was out on the drive waiting for a trip up to the local tip i noticed a small 240v fan and thought 'eureka - extra cooling fan for my mig' - yet to fit it but other than 240v as compared to the 12v jobbies in the computers they are virtually identical - Mark

 

[Robotstar5]

All our welders at work draw air out of the set, the intake grille is at the front so air is drawn over transformer & rectifier. The difference is all the controls/electronics are in a seperate sealed(ish) compartment above.

 

[voipio]

It depends on the design of the welder, particularly where the components likely to get hot are situated. Air coming out of something has a stronger directionality to it than air being sucked in to something. Think of the airflow around a vacuum cleaner nozzle with the vacuum cleaner set to "suck". It's only when things get close that they experience a significant force. If the vacuum cleaner has an exhaust port and the hose is connected to it, the air coming out will have quite a strong flow (and force) in line with the nozzle. The same is true of the inlet and exit sides of a fan, be it axial or centrifugal.

I'm not familiar with the Clarke EN90, but it looks like it's a transformer type device, and the parts likely to get hottest are the transformer itself and the rectifier/heatsink assembly, so it would be best to point the outlet of the fan directly towards these components. If, on the other hand, it's a switched mode (inverter) device and the heatsinks with lots of transistors on them are located close to ventilation grilles, then having the fan pull air out of the cabinet might be best, since the airflow coming in through the grilles will have some directionality towards the heat sinks. If the power semiconductors and heatsink are located in the core of the welder, then having the fan blowing towards that will produce the strongest cooling effect.

 

[Bristolbulldog]

Cannibalise a dell or something, and use the shroud to direct airflow over the case.

If you have just one fan, it's better to direct the airflow in a pressurised case, than cause a general vacume. 95% of servers work in this manner.