Air doors/curtains

[US Iceman]

I'm researching information on air curtains and doors. Does anyone have some comments on these for cold storage warehouses (freezers especially)?


What has your experience been? Good and bad...

Do they work?

Are the generally maintenance free?

I would appreciate hearing the types of problems and successes you have personally seen.

Thanks.

[smpsmp45]

Are you looking at Doors as well as Aircurtains or only air curtains?

We can share a lot based on our experience.

[US Iceman]

I'm specifically interested in air curtains and their benefits and problems. Frost prevention on cold surfaces, load reduciton, cost of operation, etc.

Thanks for your interest...

[Samarjit Sen]

We have used Air Curtains for air conditioning areas. It is quite effective. But in couple of our projects our clients insisted for air curtains in Cold Rooms. It has been a total failure. It is much better to use pvc curtains, they are very effective in Cold Storages.

[US Iceman]

But in couple of our projects our clients insisted for Air curtains in Cold Rooms. It has been a total failure.

OK, but what failed and why? Details please.

[Samarjit Sen]

The cold room air were just blowing out and was unable to hold the temperature inside the cold Room. After we removed the air curtains and provided the pvc curtains there were hardly any leaks and the cold room were holding there temperatures.

[US Iceman]

The cold room air were just blowing out and was unable to hold the temperature inside the cold Room.

Was this a fault of the air curtain though?

The plastic strips are more effective, but most people do not like them.

The reason for posting this thread was to start a discussion on the problems with air infiltration into freezers.

I have seen some air curtains on freezers that were terrible. I have also looked at some that were very promising.

At the moment this investigation is for a client who has frost problems at both of his facilities. The issue becomes one of solving the problem in a retrofit situation (of course for very little expense, but I doubt this will be the case).

[frank]

Hi Iceman

Have a look at the following website - one of the leading air curtain companies in the UK.

http://www.thermoscreens.com/en/index.html

Click on the 'Latest news' tab and view the 8th June info - about Cold Rooms (called Ambient Air Curtains here)

Frank

[US Iceman]

Thanks Frank. I will look into those more carefully later this evening. After a quick look, those air curtains appeared to be similar to a Mars unit. Although, the link you provided seems much better with the high velocity nozzles.

Here is a link to the air curtain I have been looking at:
http://www.hcr-inc.com/

Oh, BTW.... The Spice Girls are getting back together! That should make your day.

[frank]

Oh, BTW.... The Spice Girls are getting back together!

You cheeky Bu**er.

http://news.bbc.co.uk/2/hi/entertainment/6246448.stm

Looks like the States gets 3 venues but we only get one (even that's one too MANY)

[US Iceman]

You cheeky Bu**er.

That sound you heard was me falling out of the chair laughing.

Sorry, I could not resist. If you missed them the first time, I could share my daughters copy of their CD's and movie with you. Just in case you want to reminisce.


.... still laughing.... exit stage left.

[Samarjit Sen]

An air curtain should have high velocity and properly selected. While it keeps out the flies and insects, it can not, or rather I am yet to see keep out the infiltration. In our country the available air curtains are not effective.

I have found that the pvc strip curtains with 50% overlapping, much more effective as well as cost effective.

[US Iceman]

This problem has been going on since the freezer was first built. The warm moist air entering the freezer flows through the top half of the door when the door is open.

A lot of frost collects on the inside of the door, racks, and product. The air curtain link I posted seems to take care of this without using a desiccant dehumidifier on the dock area.

At this time I'm still investigating...

[Andy P]

Hi Iceman,

We had a fairly poor experience with air curtains about 10 years back. I came to the conclusion that for a room with only one door where there would be very little pressure difference across the opening the ymight be useful, but where there are two or more openings into the room they were pretty well useless. The thing that amused me about them was that the manufacturers quoted "efficiencies" - eg "our air curtain is 95% efficient", which sounded fine until you realised that the benchmark was a (permanent) hole in the wall, not a door. In other words an air curtain that was 95% efficient would only let in 5% of the moisture that a permanent hole the same size would let in.

I also found one on a site where the dehumidifier had got stuck permanently in defrost mode. This was quite obvious because there was warm air coming out the door nozzles, but nobody noticed for days (or possibly weeks).

I tihnk there's no substitute for rapid roll doors backed by solid panels

cheers

Andy P

[US Iceman]

In other words an Air curtain that was 95% efficient would only let in 5% of the moisture that a permanent hole the same size would let in.

I think you hit on one of the topics the marketing departments don't want us to realize. When you ask questions about quoted performance figures, you sometimes get a lot of feet shuffling and sideways glances.

I also get enjoy hearing these stories and claims when someone says 95% efficient or high efficiency.

My standard question is: Compared to what?

[smpsmp45]

Dear US ICeman, What is the conclusion?

[US Iceman]

Well, I suppose we have not really reached one yet. You were the first one to post again in this thread for some time. And to be honest I have not followed up on this topic lately.

This is going to come up again on a project we are currently investigating, so we shall see...

[Samarjit Sen]

Hello Mike,

The link that you gave for the air curtains seems to be quite different. I have sent a mail to them to let me know more details, as if it is effective, I might be able to use it in my projects.

[US Iceman]

Hi Samarjit,

This is the only air curtain I have seen that seems to make sense. The design of the air flow appears to correct some of the problems associated with "other" air curtains.

I have actually seen some of the curtains shown in the link, and I was quite impressed with their operation.

One of the RE members here (nh3wizard) has some of these in one of his facilities I and think he is happy with their operation.

Sales literature is always interesting, but the real proof comes from happy owners!

[Samarjit Sen]

yes Mike I saw Nh3 wizards comments on the air curtains. That is why I have sent a mail to them. You are right, the literatures promises a lot but the fact is something else.

[smpsmp45]

Dear US ICeman,

We had seen in Germany, the Doorless cold stores & infact I had posted a link to that company. Your link of US doors is similar to that concept. The client using those curtains with no doors was happy on the performance.
We tried to get that one in India, but they were reluctant as they said they can not service only One door as in India this product has no much market.

[US Iceman]

Hi smpsmp45,

I reviewed this thread quickly and could not find a link posted by you. Was it in a different thread?

Could you post it in this thread please? That would be helpful to future viewers of the thread also.

Thanks.

[TXiceman]

Mike, have you looked at the Thermo Shutter from Mycom. Seems to be pretty nice. They had one at RETA in Dallas.

But with any air curtain, you will still need a hard door for positive shut of the two temperature areas. The air curtains only reduce the infiltration to a small amount instead of a large amount.

Ken

[US Iceman]

HI Ken,

Nope didn't see the Mycom product.

This problem with air curtains pertains to those facilities where there is a lot of traffic so as you know the "hard" doors are kept open.

As you've stated my main concern is trying to minimize the effects of the door being open. Nothing is 100% effective (except a closed door ), but I do want to look at keeping the infiltration to the lowest possible level.

[TXiceman]

The hard door is a back up for when the box does not have traffic...like at night or part of the day. You don't want to be banging the door open and closed on every traffic.

I can't find my link to the product. Call your local Mycom rep. He will have to get you in touch with there expert in California.

Ken

[aawood1]

Hi Iceman, We also had a bad time with a Air curtains. But some of this could be down to the way the coldstore was built with a door each side about 400 feet apart. ( store size about 600 feet X 200 X 35 feet hight.) They even tryed to make it work by fitting an air lock tunnel 15 feet long with soft pvc flaps after the air curtain point. How it was ment to work was you opened the main doors and then used the air curtain until you had loaded up the lorries. We are now back on just the main auto doors. But have a mate with a small coldstore about 150 feet X 50 feet X 12 feet high and only one door and that seems to work OK with an air curtain.
Arthur.

[US Iceman]

Hi Arthur,

But some of this could be down to the way the coldstore was built with a door each side about 400 feet apart.

If both doors are open at the same time, I would not expect air curtains to offer any positive effect for that facility. Cross flow infiltration is the absolute worse problem to solve.

In effect, the cold store ends up becoming a wind tunnel between the two doors and the infiltration and frost problems become major headaches.

As a rule, doors on opposite sides should never be done.

[fridge tiff]

Our main cold rooms were originally fitted with an air curtain which wasn't too bad, the main problem was during large storing operations when the stores guys would wedge a piece of wood in the switch to turn the curtain off. They didn't like the cold air flow (poor sensitive little bunnies.) We fitted plastic curtains instead which don't give the level of frosting the air curtain did (especially when the ship is in humid climates) and seem to work better. Of course, some people still tie them back...

[smpsmp45]

http://www.refrigeration-engineer.co...ead.php?t=8295

Dear Us ICeman this was the thread. The company is Biddle . They have a site as well

[aawood1]

Hi Iceman,

(As a rule, doors on opposite sides should never be done.)

This is what we said when the management of the day said that this is what they wanted fitting after talking to the coldstore door makers. We just had to pick up the bit's after they left site and did not want to come back. What they said was that as one door was inside the factory it would work and save money.
( all it comes down to is what do we know)
All the best Arthur.

[US Iceman]

Hi Arthur,

I thought you already knew the problems associated with the doors, but I threw that in for others reading the thread later.

It's really very sad when owners/management trust salesman rather than their own people. I see this happen all too often...

The best fun is reminding the boss of their infamous decisions every chance you get.

[aawood1]

Hi Iceman,

The best fun is reminding the boss of their infamous decisions every chance you get.[/QUOTE]

I wish I could but they seem to be moved on before you can say anything 3 factory managers in the last 2 years.
Arthur

[TXiceman]

It's really very sad when owners/management trust salesman rather than their own people. I see this happen all too often...>>>>>

Hey Mike, watch it. I am a salesman here.

Ken

[US Iceman]

Sorry Ken, I made that sound as if all salesman were bad. They're not...

It's like everything else, there are people who deliver and others that take.

I've seen this work both ways. Sometimes the right salesman helps, sometimes the wrong salesman wins the order on false or incomplete promises. I think you would consider that a fair statement

[Samarjit Sen]

Sorry Ken, I made that sound as if all salesman were bad. They're not...

It's like everything else, there are people who deliver and others that take.

I've seen this work both ways. Sometimes the right salesman helps, sometimes the wrong salesman wins the order on false or incomplete promises. I think you would consider that a fair statement

Mike you are absolutely correct. It is the wrong salesman/salesengineer who wins the orders with false promises. I have seen it too manu times.

I am sure Ken does not come in this category.

[US Iceman]

Samarjit,

When I was writing that comment Ken did not even cross my mind as one of the "bad" ones. It's easy to tell who the bad salesmen are; ask them a question and see what kind of answer you receive!

[Samarjit Sen]

Dear Mike,

Last evening I had gone to a store. They had installed an air curtain at the entrance to the door. The length of the air curtain must have been at least 6" short at both ends than the door openings. Due you think that this air curtain would work.

When you open the door there is a gush of hot air entering the store which is air conditioned.

[US Iceman]

Samarjit,

I think you answered the question for me.

Due you think that this Air curtain would work?

When you open the door there is a gush of hot Air entering the store which is Air conditioned.

I know some of the casinos, etc. use these air doors to allow free flow of traffic. Even if the curtains are 20% effective, that is 80% of the infiltration air that does not have to be air conditioned.

That might be OK for HVAC purposes, but for refrigeration I do not think these curtains provide sufficient restriction to warm air flow infiltration for coolers or freezers.

The thing to be careful of is as Andy_P pointed out earlier...What is the % effective rating based on?

[Samarjit Sen]

Dear Mike,

These Air Curtains are not effective. What I found yesterday that even with the air curtains on, there is a great deal of warm air infiltration. If you talk in terms of % of efficiency , then I feel that the air curtains are 40% efficient in the case of HVAC and 0% in refrigeration. To avoid infiltration, I feel the best would be to have a small Ante Room. This will limit the infiltration .

[Samarjit Sen]

Dear Mike,

Yesterday the Export Manager of Dan Doors from Denmark came to meet me. We were discussing about the various options of the doors available with him. He told me that they have recently come up with a flexible canvas door with pvc window for see through. These doors rolls up as you approach and then it rolls down. As it is a new product, he did not have the relevant brochures. However I have asked him to send me the details in pdf form so that I can mail it to you. I was thinking that this might be a good replacement of air curtains.

[frank]

Dear Mike,

Yesterday the Export Manager of Dan Doors from Denmark came to meet me. We were discussing about the various options of the doors available with him. He told me that they have recently come up with a flexible canvas door with pvc window for see through. These doors rolls up as you approach and then it rolls down. As it is a new product, he did not have the relevant brochures. However I have asked him to send me the details in pdf form so that I can mail it to you. I was thinking that this might be a good replacement of air curtains.

They are not new here in the UK Samarjit. Have a look here or type 'high speed door' in Google

[Samarjit Sen]

Thank you frank for the link. I feel that these type of high speed doors can be a good alternative to strip curtains in Cold Rooms in addition to the regular swign or sliding doors.

[smpsmp45]

Vertical rapid doors for cold stores is very problematic as water drops down after the curtain rolls up. That gets iced up in the door pathway. Recently, we have installed Horizontal rpaid doors & those are wonderful. The water does not get in door path & the door manufacturer has provided water drain system with heaters etc & they work very very good

[smpsmp45]

These doors were imported from Sweeden. The vertical Rapid doors work well in production facilities & packing areas.

Ofcourse these doors are used for high movement cold stores & the insulated door is manual operation & this rapid door is motorised.

[Josip]

Hi,

not easy to answer, but...

for me the best will be to install a small ante room with automatic doors and air curtain...and within the freezer room another "doors" with silicone curtains..

Curtains will kept cold air within freezer room not allow the warmer air to get in...on outside wall of ante room we have automatic doors and air curtain keeping "warmer" air within manipulation corridor...

See attached pdf drawing...

Freezer room-ante room- corridor.pdf

This system is installed in one cold store in Saudi Arabia to prevent intake of warm/hot and humid air into freezer room..

Also evaporators 3 in room (custom made)

Evaporator with cover 1.JPGEvaporator with cover 2.JPG

are equipped with counterweight plastic covers at air outlet to minimize escape of water fog during defrosting, possible to defrost one by one while other two are working...unfortunately defrosting system is only with water and need some longer time (old Samifi design...still working)..

I do not know now but I think they stop other two evaporators during defrosting...

Hope this is of some help

Best regards, Josip

[unclejackieboy]

Do they work? Not in every application. What problem are you trying to solve? What size door openings? Temp inside and out? Frequency of passage through curtains. What kind of "traffic" - fork trucks, pallets jacks, people???

[Psychro]

Hi Iceman

The modern method of reducing ingress of moisture into cold stores is to use very dry air from a desiccant dehumidifier. A number of leading UK supermarket chains are now using this method in their cold storage depots The dry airduct outlet is designed to produce a curtain of dry air down across the face of the doors (on the warm side). I have recently supplied a number of desiccant dehumidifiers for use in supermarket cold stores where the DH units supply air at minus 25°Cdp. This system dramatically reduces ice build up on door frames, ceilings and floors (health & safety) and also improves efficiency of dx cooling coils (reduced latent load and defrost cycles). If the dehumidifiers are located in the loading area (2-5°C) then these areas also benefit from a much reduced humidity.

[US Iceman]

Hi Psychro,

Welcome back. It's been awhile since I have seen you here.

I agree with what you are saying. Based on what I have been seeing there are essentially two methods for dealing with this issue; moisture removal or moisture containment.

I suppose what I will have to do is analyze the equipment and operating cost of the two methods to see where the best benefit is to be found.

Of course the desiccant system is more straightforward than the air curtain, as the air curtain has more unknown factors than the desiccant.

Thanks for your input.

[Psychro]

Thanks Iceman

Nice to be back - but even nicer being missed.

Regards
Psychro

[IceMan_4000]

Thermo-Shutter videos

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Running http://video.google.ca/videoplay?doc...45768&hl=en-CA