Sizing Back Pressure Valves

[bmw318be]

Hi,

What is the most practical variable to considered when sizing the back pressure valve for the metering pump ?
In most of the cases, the pump process discharge flow is having a bigger size such as 2" port diameter

Given rated flowrates of the pump would allow me to determine max pulsating flow of the back pressure valvr stated in some manufacturer such as Grifco or plasomatic valve.

If based on this parameter the valve selected smaller such as

1. 1" back pressure valve for 2" process discharge pipe.

2.2" back pressure valve for 3" process discharge pipe.

And some I discovered the manufacturer do not manufacture the size matched to the pipe, howver the pulsating flow is sufficient.

Another question, most the curves pulsating flow vs Pressure are based on water,is it important to consider other correction factors such as viscosity and sg to get the correction factors. I have not seen there is such correction factors involved.
Appreciates your advise

 

[gerhardl]

Some questions are best answered by contacting the product supplier directly.

The reason for this is that for any correct valve-dimensioning a large number of details must be known, including in many cases details of the piping layout and all attached equipment, along with full details of all variables of flow and fluid.

At the same geometrical connection size valves of equal type will differ in inner solutions, flow characteristics, and capacity from model to model and producer to producer.

A general answer based on insufficient information may well lead you to a poor or wrong solution.

 

[LittleInch]

I've never seen a back pressure valve able to react fast enough to do anything significant to smooth out a pulsating flow, which is what you seem to be asking? However if the vendors advise it can do that role then you need to talk to them.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[georgeverghese]

You havent said what type of metering pump this is. There is a better chance of a backpressure valve working if the pump is a gear or lobe or vane pump where pulsations in discharge flow are minimal.

For a plunger or recip pump, a lot depends on pulsation attenuation at the discharge end - if you ask me, I wouldnt push my luck on this option anyway.

 

[wagga]

I would think that valve sizing (including relief) is more of the Process Engineer role?

 

[bmw318be]

Hi it is hydraulic dosing pump, normally it is purchased as part of a skid builder scope.

We normally size bassed on pulsating flow as per griffco website

http://www.griffcovalve.com/products/back-pressure-valves/g-series

In most of the time the pump port is larger than the valve despite merting pulsating flow