2 replies to this topic

[bhaskaran]

In sizing of pressure safety valve ulimately we are finding the orifice area .Orifice area was chosen as per the ASME section VIII guidance( D,E,L,M)

The orifice area for L = 2.853 SQ.Inches & size (in x out) = 3 x 4

dia of orifice from the above orifice area comes to 1.9 inches only (arriving dia from Pi/4*d2 = 2.853 in2)

i have following clarification
i)In safety valve orifice area represents what?
ii)Orifice dia comes only 1.9" whereas inlet safety valve flange size was 3"?

Kindly clarify

Regards,
Bhaskaran.r

[djack77494]

Bhaskaran,
First let me suggest that you choose more carefully which forum to post questions to. You would likely achieve a better response if this were posted to the relief valve forum where the experts in this sort of matter reside.

Refering to a safety valve orifice area is a bit of a misnomer since a PSV more closely resembles an isentropic nozzle rather than an isenthalpic orifice. Nonetheless, the term is widely used. It represents the minimum cross-sectional flow area available for flluid flow. Since "the orifice" is a restriction internal to the PSV, I don't understand why you are surprised that the orifice diameter is smaller than the flange. It takes some space to put all "the workings" of the PSV inside the valve body.

[bhaskaran]

Bhaskaran,
First let me suggest that you choose more carefully which forum to post questions to. You would likely achieve a better response if this were posted to the relief valve forum where the experts in this sort of matter reside.

Refering to a safety valve orifice area is a bit of a misnomer since a PSV more closely resembles an isentropic nozzle rather than an isenthalpic orifice. Nonetheless, the term is widely used. It represents the minimum cross-sectional flow area available for flluid flow. Since "the orifice" is a restriction internal to the PSV, I don't understand why you are surprised that the orifice diameter is smaller than the flange. It takes some space to put all "the workings" of the PSV inside the valve body.

Thanks jack for your reply.Hereafter i will be careful in putting questions in right forum.Thanx for your advice