8 replies to this topic

[Narnia]

Dear all,

I have performed the line sizing and pressure calculations of DOW vapors,its vent & drain line and also of Virgin EG.Please guide me about recommended velocity & pressure drop limits for these chemicals and how their sizing will be performed.

is there some calculations available,please provide.

also guide me about the recommended velocity limits of Chilled water and instrument air.

Thanks

[ankur2061]

Narnia,

Refer the link provided below:

http://www.cheresour...1897#entry51897

Regards,
Ankur.

[Narnia]

Dear Ankhur,

but this post din't reflect my answer,i want how to calculate line size of EG and DOW vapors,what are their velocity limits,
also of chilled water

thanks

[ankur2061]

Narnia,

There is nothing special about EG and Dowtherm vapors if they are saturated vapors. Saturated vapor velocities are provided in the spreadsheet attachment with the link provided in my earlier post. Also don't forget the allowable pressure drop for your system when using high vapor velocities.

For more information on Dowtherm A or Therminol VP-1 (DP:DPO eutectic mixture) you can visit the websittes of Dow or Solutia. These provide properties related information.

Regards,
Ankur.

[Narnia]

whats about the chilled water

[GS81Process]

It probably doesn't hurt to contact DOW. They have good engineering information available and may even be able to recommend to you appropriate line velocities and pressure drops.

For chilled water I would allow a maximum of 3.5 m/s and 30 kPa/100m for pump discharge lines. This is a rule of thumb only though and you should consider the specifics of your application.

Edited by GS81Process, 11 January 2012 - 09:44 AM.

[Rahmady]

i usually do line sizing for oil and gas industry, but i think it has same rule of thumb for the sizing criteria. (CMIIW)

for liquid:
Pressure drop shall be less than 0.5 psi/100ft
liquid velocity shall be less than velocity of erosion
velocity erosion = 100/(liquid density)^0.5
liquid velocity shall less than 15 ft/s

at suction line (pump) --> still for liquid
pressure drop shall less than 0.1 - 0.4 psi/100ft
liquid velocity shall less than 5 ft/s

at discharge line (pump) --> still for liquid
pressure drop shall less than 4 psi

hope it useful.

[kkala]

The post by Rahmady can be a useful contribution to general line sizing criteria, reported in the last posts of http://www.cheresour...id-line-sizing/. I write parts of the post here below, with some clarifications requested for easy use. Reply is really welcomed. The data concerns liquid line sizing mainly for oil and gas industry (CMIIW).

Pressure drop shall be less than 0.5 psi/100ft (where, at pump discharge?)
liquid velocity shall be less than velocity of erosion
velocity erosion = 100/(liquid density)^0.5 (velocity of erosion in ft/s? liquid density in lb/ft3?)
liquid velocity shall less than 15 ft/s

at suction line (pump)
pressure drop shall less than 0.1 - 0.4 psi/100ft
liquid velocity shall less than 5 ft/s

at discharge line (pump)
pressure drop shall less than 4 psi (4 psi/100 ft? it looks on the high side for general use).

[Narnia]

I need to know Dowtherm vapors line recommeded velocity limit,is it above 20 mtr per sec or in range of < 10 m/sec. pls guide
is it any limit for pressure drop,
looking for good information on this,thanks