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Anonymous Poster

Confined Space

02/27/2008 2:14 PM

When working in a confined space, opening only on one end what is best to do to move stale air ?
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phoenix911
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#1

Re: confined space

02/27/2008 2:37 PM

Assuming you have training to work in a confine space.

We use a blower with flexible tubing running inside aerate the area.

Size of blower will differ with the cubic ft. of area the has aeration.

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Anonymous Hero
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#2

Re: Confined Space

02/27/2008 4:49 PM

That would be our company's men's room.

All you can do is hold your breath.
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Vulcan
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#3

Re: Confined Space

02/27/2008 11:34 PM

You use a blower along with a flexible pipe to push good air (blue) into the space at the far end which pushes the bad air (black) out the opening. As mentioned already, you have to size the blower and pipe for the size of the space.

Oh, and make sure the blower is sufficiently far enough away from the opening so that it doesn't push the bad air back into the space. Should go without saying but people sometimes don't see this.

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Sparkstation
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#4
In reply to #3

Re: Confined Space

02/28/2008 12:50 AM

Hello Vulcan

You gave nice diagram, plus satisfactory explanation.

This earned you a "Good Answer Mark", also.

Kind Regards....

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#7
In reply to #4

Re: Confined Space

02/28/2008 2:18 AM

Thanks Sparks!

We've got these things in our factory since suffocation is a real danger when going inside the tanks. We had one guy who just peeked inside the tank and fainted. He was hanging half-in and half-out of the manhole. Fortunately, one of our rules is to also have someone else stand by (buddy system). He got the guy out pretty quick.

He called in sick the next day saying he had a huge headache! Could have been worse. Hard lesson to learn.

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phoenix911
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#10
In reply to #3

Re: Confined Space

02/28/2008 9:57 AM

Should go without saying but people sometimes don't see this.

Always worth saying.....

nice diagram.

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csoulpro
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#5

Re: Confined Space

02/28/2008 1:19 AM

To me, there's only two types of air flow in that situation. Hot (warm) air circulation, and fresh - stale air recirculate. If you can tap into any fresh air source (window, hallway) you can use this ingenious tubing that I use to circulate air and hvac systems. It even has absorbers, so I can limit the noise coming from any fan or AC unit. The beauty is it's made to fit in a 4" standard stud. It can get very complicated, and it depends on your structure, etc. I have always found solutions using this product whether it was an install or retro fit. Go to http://csoulpro.com/HVAC_Systems.html and contact for further information.

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TerryChng
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#6

Re: Confined Space

02/28/2008 1:31 AM

It depends on what process you are doing inside the confine space. If you are performing welding, it would be better to 'suck' the fumes out rather than blow air into the confine space.
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dragonbreath
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#8

Re: Confined Space

02/28/2008 7:31 AM

go to this link for what you need to know about confined spaces

http://www.hse.gov.uk/pubns/indg258.pdf

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user-deleted-9
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#9

Re: Confined Space

02/28/2008 8:10 AM

There are several risks.

One is lack of oxygen in the confined space. The atmosphere should contain 20 percent. Blowing air into the space will help. Make sure the volume of air blown into the space is sufficient for 30 air changes per hour.

The next problem is hazardous fumes. These pose health risks as toxic or explosive. Examples are methane, hydrogen sulfide, and many others.Blowing air into the space may help but remember that these gases may be heavier than "air". In this case, the hose needs to go deep into the bottom of the space for purging of the whole space.

Blowing air into the space will not always work. Sometimes you will need to supply breathing air in an external tank (i.e. SCUBA). Welding is an example.

We don't allow confined space entry by one man. A second person must be on standby outside the space to assist the entry person if trouble develops.

There are meters to test the oxygen content and exposive gases in the confined space before entry. Sort of like a high-tech version of the coal-mine canary. The instrument measures for o2 and LEL (lower explosion limit). If the atmosphere is not suitable for entry, the space is vented using blowers and tested again. Only after the space is safe, can the entry be made. Fresh air is blown into the space throughout the work. The meter can even be taken into the space by the worker for real time monitoring in the space while the work is underway.

I can provide more information on this if the interest is there in the CR4 forum.
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Johan van Niekerk
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#11

Re: Confined Space

02/29/2008 2:21 AM

I would agree with Vulcan on forcing new air into the space but I want to stress that in the case of the entrance on the top, like a manhole, the poisonous gases may be heavier than air and may remain inside.

In all cases a safety line should be used with a buddy at the entrance.

An air supply to the person in the space would be the safest.

Safety hoods are available that covers the face and provide air to the user.

Where is the old Davies safety lamp? This could give an indication of the condition of the air inside .

A suction system is seldom efficient as it tends to remove the air in the vicinity of the suction pipe or fan only and never reaches the extremities, whilst blowing in air has a bigger effect on putting the whole body of air into motion.

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Anonymous Hero (1); csoulpro (1); dragonbreath (1); Johan van Niekerk (1); phoenix911 (2); Sparkstation (1); TerryChng (1); user-deleted-9 (1); Vulcan (2)

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