BA Duration Tables

[Sara Whitehead]

Hiya, I was wondering if someone could point me in the direction of BA duration tables?  I would also like a good example of as BA tally board - any suggestions, Thanks SJ

[terry martin]

can't send a link but if you email me i can forward you what you need.

bear in mind though that different Brigades use different equipment so,

the boards will vary, as will the duration times.

it might be usefull to know why you need the info.

also

[Mike Buckley]

Try www.vass.co.uk they may have some old BA Boards for sale.

As far as calculating the duration goes, there were two types either a straight duration table where the times were given for different pressures or the 'Dorset' calculator which is a round disk where you match the pressure in the set against the time in and you cane read the time of whistle from the dial.

The only thing that will differ between brigades is the capacity of the cylinder. The duration of the set is worked out from the volume of air in the cylinder and an estimated usage of 40 l per min.

The formula is the contents of the cylinder divided by 40 and subtract 10 (time of whistle). You get the contents of the cylinder by working with the pressure. A 2250 litre cylinder holds 2250 litres at 200 bar. hence if the pressure is 190 bar the contents will be 190 divided by 200 multiplied by 2250.

Oh happy days at Moreton!

[Sara Whitehead]

Thank you gentlemen for your answers,  I will look up the suggestions. As for Terry's question on what I will need it for, I am the safety officer on a vessel, I have a 4 man fire team, we have 2 different types of BA kit, we have the Draeger PA90+ and the Draeger PAS Marine both which are used with a 300 bar tank.  
In the event of an offshore emergency our own response team comes into play, we are not professional fire-fighters we are trained crew members.  I hope this answers your question.  Thank you both again. SJ

[Mike Buckley]

The make of set will not make any difference to the duration tables provided they are the same type ie compressed air. What will make a difference is the capacity of the cylinder but it sounds to me like you use the same size of cylinder for both sets.

You say the tanks are 300 bar, the thing to check is that their capacity at that pressure ie how many litres of air they hold. All the tanks should have the same capacity.

If they don't have the same capacity then you have problems, as the duration tables will differ for the different tank capacities. Basically a tank holding 1800 litres of air will run out faster than a tank holding 2250 litres.

[nearlythere]

Thank you gentlemen for your answers,  I will look up the suggestions. As for Terry's question on what I will need it for, I am the safety officer on a vessel, I have a 4 man fire team, we have 2 different types of BA kit, we have the Draeger PA90+ and the Draeger PAS Marine both which are used with a 300 bar tank.  
In the event of an offshore emergency our own response team comes into play, we are not professional fire-fighters we are trained crew members.  I hope this answers your question.  Thank you both again. SJ

I would not have thought it a good idea to have different sets unless maybe they have the same working and emergency reserve durations. If not you should not send in fire or rescue crews in different sets. My advice would be to standardise sets.

[Mike Buckley]

I would agree it is not a good idea to have two different types of sets but only from the servicing and maintenance point of view as you would be doubling up on parts.

As far as the duration of the set goes the type of set makes no difference. The BA Control Boards used by the brigades are standard, all using the same duration tables. When I was in the service neighbouring brigades not only had different models of sets but they had totally different manufacturers as well. The FSC BA school has a variety of makes of set so that students can use the set they are accustomed to in their brigade.

The set should have the whistle set so it will start to work when there is 10 minutes of air left in the set.

The critical factor for duration is not the set but the amount of air in the cylinder.

The duration tables work on the assumption that the person using the set will use 40 litres of air per minute. This is an assumption as it will vary on the amount of work the person is doing as well as their size and fitness etc. I personnally have emptied a cylinder which should have lasted 50 minutes in less than 20 minutes. On the other hand I have also worn a set, trying to conserve air, and gone far over the estimated duration of the set with at least half of the cylinder contents left.