Blast Freezer Cooling / Heating Times

[selbstar81]

Hi there,

First post so go easy on me.

I keep neing being asked by white wall contractors for max cooling / heating times to cool / heat a room in order for them to size the pressure relief valves to gaurd against walls collapsing / doors not easily opened. Now I thought I would be able to work this out quite simply but am really struggling to put an equation together. Has anyone got some form of equation that might help me here or any suggestions? It would be greatly appreciated.

[Brian_UK]

How is the time involved related to air pressure generation within the room?

Surely your blast freezer is recirculating the air within the space.

[smpsmp45]

Yes time has an important role. The faster the cooling faster is the vacuum creation. I have few charts on this. But send me a PMS then only I can send the file. I have exhausted all the slots for uploading.

[powell]

Interesting question. I did some searching and it seems each manufacturer has different specs. Here's a link to Kason's site which list how to size their pressure relief vents.

http://www.kasonind.com/images/stories/kason_accu-flow_broch_06.web.pdf

[selbstar81]

How do I send you a PMS?

[Brian_UK]

How do I send you a PMS?If you click on the members name you will see the option to send a PM.

[nevgee]

The problem occurs when the bfreezer door is closed and the freezing process is started. The warm air within the chamber cools very quickly causing a negative pressure within the chamber. If a releif device is not built into the structure of the chamber then a risk of collapse can occur. On smaller chambers usually the doors are pulled tight on their seals and become difficult to open, on large stores the whole structure can collapse.

Fermod used to make pressure reliefs and would offer a selection proceedure.

We used to cut a hole into the roof of the chamber to allow for pressure relieve ... this might not be acceptable today.