4 replies to this topic

[Sridhar P]

Dear Sir,

Pl. clarify the following.

It is the normal practice to connect the drain line of tanks after isolation valve to the overflow line. (as in the attachment case-1)

But few clients are against this concept and asking for seperate lines for drain and overflow lines.(as in the attachment case-2)


Is there any problem envisaged for the case 1 for clean liquids.

Pl. guide us.

Thanks and Regards,
P.Sridhar

Attached Files

•  Drain_and_Vent.xls   40KB   205 downloads

[Qalander (Chem)]

Dear
I will prefer Case 2 indeed! brief reasons

1)If for any reason(s) drain gets plugged/chocked no danger to overflow safety measures

2) The size of joined drain pipeline segment downstream of the junction point has to be increased ensuring no resistance back pressure for overflowing stream's safe disposal

hope this helps in way forward.

[Sridhar P]

Dear Sir,

Thanks.

[Art Montemayor]

I fully endorse Qalander's response and comments. Not only is he taking a firm stance on a potential safety issue, he is also bring out the practical fact that the scope of the quality of the two drains is entirely different due to the type of location and the knowledge of what gravity can cause in any process.

Empirically, one will almost always find that should there exist any solids or heavy components in the tank or reactor, they will most certainly gravitate to the lowest part of the vessel - the drain valve. And conversely, the lighter and cleaner liquids will rise to the top and exit through the overflow.

Experienced field engineers inherently know that it is very unwise to rely on a single, common drain system design to handle both type of liquids. The heavier and probably solids-contaminated drain will require a totally different type of piping and drain design and should not be allowed to jeoparize the effective draining of the overflow liquids. That would be asking for trouble.

[Qalander (Chem)]

Thanks! I do feel honored Art.