6 replies to this topic

[DARK_STALKER]

Can someone please tell me if there is an average value to use for resistance coefficient in a Y strainer I have searched product catalogs but only seem to find Cv or Kv values. I am working on an assignment to calculate major and minor losses in a pipe system and there is a 15mm strainer with 0.8mm screen in a section of pipe and using Darcys equation for minor losses i need the K value to solve.

Cant seem to find this information anywhere

Any help would be greatly appreciated

[ankur2061]

Dark Stalker,

I wouldn't know the K -value for Y-strainer but Fig. 17-4 in the GPSA Engineering Databook, Section 17 - Fluid Flow & Pumping gives a value of the equivalent length of Y-strainers as:

L_eq = 250*D

where:

L_eq = equivalent length

D = Nominal Pipe diameter

use consistent units

Hope this helps.

Regards,
Ankur.

[DARK_STALKER]

Thanks Ankur

So then for a 15mm pipe

250*0.015 = 3.75

I found one product specification document that show k for a similar size pipe to be 3

I have also found information that states that K will vary with time as the strainer becomes blocked and the way to model this would be to use the max dp for a clogged strainer

Regards

[ankur2061]

Dark Stalker,

Generally for any hydraulic calculations involving a Y-strainer I consider a pressure drop of 0.1 bar (1.5 psi) and be done with it unless I have other supporting data. This generally proves to be conservative enough for any pipe hydraulic calculations.

Hope this helps.

Regards,
Ankur.

[DARK_STALKER]

Is there a way to factor this pressure drop into the Darcy equation for a minor loss

I can find the major loss and because this strainer is a minor loss element I need to be able to factor it in to my original darcys equation.

Would I be correct in saying to convert the pressure drop into head loss

I found a pressure drop formula in a product specification sheet delta P = (q/Cv)^2 this gives a pressure drop of 0.6 psi

If i use the L equivalent you suggested do i just use it in darcys equation as a length of staright pipe so in the major loss section.

Thanks again you seem to be the only person helping

[breizh]

Hi ,

let you try this resource :

http://www.pressure-....mobi/1107.html,

more available using Google .

For a strainer consider 0.1 Bar as a maximum for delta P .

Hope this helps

Breizh

[latexman]

This is from my binder of "Handy Dandy Reference Materials". A long time ago I used Armstrong's Y-type strainer catalog and calculated that K_clean ~ 2. I use K_dirty = 10 for design.