5 replies to this topic

[Elvin Alishov]

Why control valve is preferred over ARV (Automatic Recirculation Valve) when pump curve is not flat ?

[fallah]

Why control valve is preferred over ARV (Automatic Recirculation Valve) when pump curve is not flat ?

 

Elvin,

 

It's really vice versa...!

 

A pump with a flat curve won't provide a situation for an ARV application as it won't lead to significant change in differential head over a wide range of flows, and even though it's supposed the ARV senses flow to activate; it is really functioned due to sensing the change in discharge pressure which, in turn, is a result of total differential head variation.

[Elvin Alishov]

 

Why control valve is preferred over ARV (Automatic Recirculation Valve) when pump curve is not flat ?

 

Elvin,

 

It's really vice versa...!

 

A pump with a flat curve won't provide a situation for an ARV application as it won't lead to significant change in differential head over a wide range of flows, and even though it's supposed the ARV senses flow to activate; it is really functioned due to sensing the change in discharge pressure which, in turn, is a result of total differential head variation.

 

Fallah,

 

Thanks for your response !

 

From control valve selection point of view, your reply is satisfactory.

But in terms of ARV working principle... In pump curve minimum flow corresponds to maximum generated differential head. If ARV working principle is due to pressure and not due to flow, how ARV will open the bypass line at minimum flow with maximum generated differential head ?

[fallah]

 

But in terms of ARV working principle... In pump curve minimum flow corresponds to maximum generated differential head. If ARV working principle is due to pressure and not due to flow, how ARV will open the bypass line at minimum flow with maximum generated differential head ?

 

 

Elvin,

 

The reason relates to the ARV operational characteristics. 

When there is no process flow in the main line i.e.the main flow sensing check valve disc senses zero flow corresponding to the high differential head, the recirculation flow through a orifice inside the disc stem going out to the by pass line and at this time the by pass is fully open. An increase in flow causes the disc will lift and the by pass flow orifice will reduce the recirculation flow. When the disc is at full lift position the orifice inside the disc stem hence the by pass line will be fully closed.

[RGS]

Why control valve is preferred over ARV (Automatic Recirculation Valve) when pump curve is not flat ?

Automatic Re-circulation Valve (non-modulating type) is not a suitable design for the following operating condition.

1. High efficiency pump (i.e flat pump curve) and drastic flow variation on pump discharge side.

Since ARV is operating based on discharge flow rate rather than discharge pressure, any variations on discharge end user flow rate (i.e flow ramp-up or flow ramp down) causes the non-modulating type ARV to open or close on by-pass side with respect to flow ramp-up or ramp down on user side. This shall generate a pressure surge inside discharge pipe line. Either to select a modulating type ARV or Self Actuated Pressure Regulating Valve for this kind of application.

 

Hope this shall make you to understand clear about the ARV working principle and it's process application.

[breizh]

https://www.pumpindu...ump-protection/

 

To support your work.

Breizh