OKAY. Appreciate the indepth perspectives and I do apologize for not being a licensed HVAC engineer. Evidently the USDA inspectors are unclear at times what the building requirements are, as they initiate and authorize changes that are clearly fixes and not radical redesigns of the facility. I was not in on the design and build of the facility, and many modifications and fixes have been made. The plant maintains a category 2 cleanliness which is excellent for a small plant. The fixes have worked well so far, and the inspectors are diligent and watching out for sources of problems.

i have insulated the pipes which supply cold wash water to the process, and yes, they should not have been routed overhead in the process space without insulation or other considerations, but again those were the inspector's directions before I got involved.....there they were.

Re: Post #8. I agree, not very clear at times what is the rationale for some of the decisions.

Re: post #13. Troll? Who'd got time for that nonsense....what you read is all there is.

Anyways, I'm done here. If you guys want to pull hair with each other, have at it. I've seen high level professional concern here and some snarky stuff. Like every other forum.

Thanks for the heads-up on how this forum works.

 

Glad you got your problem taken care of. :cheers:

 

It looks like the original poster may have departed but I worked in the ammonia refrigeration/food processing industry for 20+ years, so I figured I would chime in anyway.

Most of the USDA & other food industry rules stem from the HAACP and GMP programs. In some facilities (like beef), any condensation dripping is forbidden while in other areas it is tolerated. Like anything else, it can depend on the mood of the inspector or their interpretation of the industry's rules.

While the idea of placing gutters under the dripping areas is a decent idea, unless they are made of stainless steel and there is a documented procedure to clean them on a periodic basis, most inspectors will demand they be ripped down. They don't like catch basins where mold can grow unseen.

In most cases, insulation to the proper thickness is the industry standard. ASHRAE's Refrigeration Handbook (Chapter 10 of the 2018 version) has a number of tables giving insulation thickness for piping at various temps to prevent condensation under some worst case scenarios. Most of these values are based on thermal conductivity values from ASTM, but those are constantly changing. The easiest is to go to the insulation manufacturer with the temperature of the fluid in the pipe, the air temperature and the dewpoint/relative humidity and let them calculate the thickness required. In Post #7, someone put up a picture of a standard piping insulation cross section. The only thing I would add is a layer of paint, RG-2400 or other coating if that pipe is carbon steel or anything else that corrodes with water. Too much of my time was spent looking for rusty pipe (corrosion under insulation) when the insulation failed and water got in.

The other option is to drop the dewpoint of the space below the coldest surface temperature. The OP mentioned they had dehumidfiers, but not what type. In a 55F space, most mechanical (vapor compression) units are going to have very little capacity. The answer there is a desiccant dehumidifier. It is not impacted as much by temperature.

Wayne3298 mentioned pressure imbalance issues. That often is the source of excess moisture in a room, but sometimes it exists because HAACP rules often require airflow to go from the finished good back to the start. In other words, when you eviscerate a steer, you don't want the plant airflow to carry anything nasty and deposit on some hamburger about to get wrapped.

 

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DehuDan I'm glad you decided to post. You have some excellent points that should be considered. One problem I saw doing air balance in these facilities was all too often the basic building construct wasn't compatible with establishing the building pressure profile desired and needed. Surprisingly enough some design engineers and plant managers had no idea what the magnitude of pressure should be. One plant manager told me he wanted a building positive pressure of 2 inches. He got pissed when I told him that would shatter the windows. The exhaust fans were also in disrepair. I didn't get the jobs (there were several plants that needed done). The reason I was given for not being awarded the work was they found a better value. They ended up with cross contamination that cost them heavily. I have always wondered if they really got a better value.00 I'm thinking you have the answer to that.

 

If they skimped on their mechanicals, they probably skimped on their system for tracking lots for recalls...which means they lost their shirt.

2 inches...that's around 500 pascals. About 10x's what those blower door tests require to identify air leakage. Holy crap. The other guy probably told him he was getting 2 inches and installed something realistic.

 

Dan you got too many zeroes on the pressure. Most commercial blower door tests are at 75 Pascals with resi at 50 Pascals. The cross contamination happened more than once but to be fair I never found out the reason. Because of my preliminary survey there I am convinced the terrible building pressure profile I observed was a factor. I spent an entire day figuring out where they were vulnerable and found a lot of problems. The big dog didn't much like what I told him so I was probably better off they got someone else. Their losses were needless to say were in the millions.

 

The OP may have departed, but it’s his loss. This happens a lot on this site. Someone posts with an expectation of validation of their point of view. When that expectation isn’t reached, there is a feeling of personal offense.

Dan, thanks for posting on this thread. Professionals like yourself make this site the great place that it is!

 

71CHOPS :cheers: