How long to fill a specific volume to a specific pressure? 1

[borobam182]

Morning!

I've been asked to confirm how long it would take to fill a 445,000 litre volume to a pressure of 1.2kPa using a air source that provides 130 litres a second of air at a pressure of 620kPa.

Firstly, this seems like a very low pressure to set the volume to (1.2kPa). But' I've calculated it would take almost 7 seconds to fill this volume to 1.2kPa using this air supply.

Would that sound about right do we think??

Cheers

Craig

 

[borobam182]

LittleInch - That was a number I was given from our sales team, which came from our site team - through a few pairs of hands, it could have been misread somewhere along the line, but the instruction I have referenced 130 l/s.

As you may have gathered - this area of engineering isnt a strong point of mine, hence me approaching the group. I dont even know the diameter of the delivery hose so cant even determine if its is a realistic value.

.....Give me a pipework design problem any day.....

 

[LittleInch]

Well it is a fairly crucial piece of info so fairly dramatically affects the answer to the question you're being asked...

It could even be that the air supply CAN supply UP TO 130 l/sec, but whether it can or not is the question to be asked. It implies a pretty large air supply line and air system which may be correct, but if they think it is going to take hours then there seems to be a rather big disconnect here - perhaps they are looking a small air compressor and thinking this is going to take hours..... Who knows - we don't.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[zdas04]

If the answer you are looking for is "should it take overnight, a few hours, or a few minutes to fill?" has been answered from about 5 different approaches. If it is still filling in 5 minutes I'd be checking to make sure that gauges were on line. Sounds like your field guys will be happy with that level of precision.

David Simpson, PE
MuleShoe Engineering

In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual. Galileo Galilei, Italian Physicist

 

[borobam182]

Yes I agree - thank you for your help.

 

[racookpe1978]

Yeah, but you have a different problem as well. Might be small, because gases do mix over time, but they also mix slowly.

Smoke test, right? So the tank starts out dirty, then you are adding clean gas to dilute the smoke if I understand your statement?

So how are you going to assume the original and final "smoke" is well-distributed? That is, if you air adding the diluting ((clean ?) compressed gas into the 15715 ft3 (443 cubic meter) tank from just one nozzle very slowly, are you sure the final gas + diluting clean air is going to be mixed thoroughly? If there's a difference in density, the mixing will be even less.