steam mains air removing 1

[kszyho100]

Hi

At the end of steam mains which works periodic (8 hrs per day) thermostatic air vent is installed.
I wonder if there should be fitted check valve after thermostatic air vent to prevent air to come back when steam line is cold.
What do you think?

 

[Compositepro]

If you do not have air in the line what will be there instead? Vacuum? Condensate? Choose what you want and design to assure it. Air seems a good choice in many cases.

 

[bimr]

If the steam line only works periodically, then you pull a vacuum when the steam cools. Most of these air vents also function as vacuum breakers.

Does the equipment that the steam line services have a vacuum rating?

http://www.tlv.com/global_pdf/tii/e-pamphlet-12-hp.pdf

http://www2.spiraxsarco.com/us/pdfs/IM/im-4-105-us.pdf

 

[kszyho100]

Steam line has no vacuum rating. I think i will leave open end of air vent to the atmosphere.

Thank you for your help.

 

[zdas04]

Now you see the reason that we don't use steam for pneumatic controls. The condensing thing can be a really big deal.

David Simpson, PE
MuleShoe Engineering

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

 

[ccfowler]

zdas04,

YES! But in addition, use of thoroughly dry air is almost always a necessity for good pneumatic systems--particularly where freezing temperatures can be anticipated.

Valuable advice from a professor many years ago: First, design for graceful failure. Everything we build will eventually fail, so we must strive to avoid injuries or secondary damage when that failure occurs. Only then can practicality and economics be properly considered.

 

[LittleInch]

process gas at low pressure can also create water drop out and freeze....

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way