Moisture Eliminator/Exh. Louver Sizing-Offshore application

[biddu]

Dear Friends

Could someone please advice that what kind face velocities are generally considered for sizing Exhaust Louvers and Moisture Eliminators at air intakes

Iam concerned about Noise and pressure drop. Is 6 m/s face velocity is good enough.

Any information about any supplier specific website with noise and pressure drop data would be higly appreciated

We have follow Norsok S-002 with very strict noise requirements

 

[AbbyNormal]

The louvers will have charts of free area and then pressure drop, water carry etc based on the velocity thorugh the free area.

Not familiar with your standards, but the more resistant to water the more resticitive.

Take the "V" out of HVAC and you are left with a HAC(k) job.

 

[imok2]

500 ft/min for OSA intakes and 700 ft/min for exhaust of free area

 

[ChasBean1]

A couple links:

http://www.greenheck.com/products/louvers/

http://www.ruskin.com/louvers/

6 m/s velocity at an intake louver is more than twice what I would want to see. At an exhaust louver it may not be so bad.

 

[biddu]

Thanks Chasbean1 and Abbynormal. We dont have Louvers at intake. We are putting marine grade Moisture Eliminators only at the air inlet which are sufficient to stop water ingress and take out salt also.

I have further investigated this matter and to my surprise that in few of the old offshore projects specifically drill ships, designers have considered upto 8m/s.

My main concern is Noise. For offshore projects there are some very strict noise requirements from norwegian authorities. Are there some graphs or charts avaialble where we can see relation between velocities and noise. Pressure drop is not a problem.

 

[MikeHalloran]

I have no idea where to get them, but I have been in a few yacht engine rooms equipped with noise suppressors that resemble coarse grills or louvers, apparently made of foam. The openings will pass serious amounts of air, or a wrench, i.e. there is a straight visual path through the bulkhead, but they are amazingly effective at suppressing Diesel noise.




Mike Halloran
Pembroke Pines, FL, USA

 

[AbbyNormal]

ChasBean1 (Mechanical) 13 Oct 06 14:26
A couple links:

http://www.greenheck.com/products/louvers/

http://www.ruskin.com/louvers/

6 m/s velocity at an intake louver is more than twice what I would want to see. At an exhaust louver it may not be so bad.

Those are my favourite manufacturers chas, the most common louver I use is Ruskin's EME6625D, it is Dade County approved for 'large misslie impact' and it somewhat resistant to wind driven rain, but if there is a hurricane all bets are off, it becomes blowing steam and a lot of water gets through.

The ruskin submittal is

http://www.ruskin.com/catalog/servefile.aspx?id=404

and it shows the free areas of the various louver sizes as well as the pressure drop based on the velocity through the free area. The larger louvers are about 42% free area, the smaller ones less than say 24x24 are much more restrictive as the back side is braced with angles to strengthen it up for passing the missile impact test. A 12x12 louver will have an open slot on the back that is about 8"x2" and that is the free area.

Just trying to emphasize to the Original Poster that it is important to verify how louvers are rated, and to look at the free area of the louver and not just a face velocity. The free area velocity will be a lot higher than the face velocity.

Greenheck makes a vertical blade louver that is more resistant to wind driven moisture than the EME 6625D however to the best of my knowledge it is not certified to the large missile impact test I need down here.

The test is to with stand three consecutive hits of a 2x4 at 35 mph. I always hear the rumour that at 55 mph, a 2x4 will penetrate concrete block.

Greenheck is a first class company in my opinion and if the local representative ever offers you a factory tour in Wisconsin, it is well worth the trip. I found their kitchen ventilation demonstration to be quite informative.


Take the "V" out of HVAC and you are left with a HAC(k) job.

 

[AbbyNormal]

The "Kynar 500" type of finishes are the popular finish here for louvers and archtiectural metals exposed to the ambient air.

If you have dissimilar metals exposed to that air you will get corrosion. There are many coatings for heat transfer coils but they ultimately fail.

The most successful type of coil that I have seen here is the all aluminum spinefin coil, originally used by GE and since incorporated into the small American Standard and Trane line of air cooled condensers. Be 6 tons and smaller nominal capacity only, I wish larger equipment was made with spinefin.

Seen copper tubes/copper fin coils fail miserably as well however I suspect a slightly different grade of metal used in the fins compared to the tubes as well as the proximity of a 'bad' over head electrical service.

Example of a Bronz Glow coating that did fairly well, they have since revised the paint they used to stencil on their logo.

Take the "V" out of HVAC and you are left with a HAC(k) job.

 

[biddu]

Dear AbbyNormal

Thanks for the valuable information. I tried to search Ruskin Website for Moisture eliminators but It seems it is not in their product range.

Do you have any similar information for Moisture Eliminator with a Coalescer Pad. We have only moisture Eliminators with a Coalscing pad at inlet.

 

[AbbyNormal]

No,I have only seen moisture eliminators as an option with built up central station air handlers

Take the "V" out of HVAC and you are left with a HAC(k) job.

 

[stanlsimon]

Trane used to offer a moisture eliminator for air handlers. It was a series of thin metal plates formed into sine wave shapes and set closely together. If you have oil money they can build one for you I'm sure. Would you like gold or silver plating?