How do enter a pressure regulator into the database?

[Samantha]

Hi yall,

I'm having to enter a few pressure regulators into our database. I've attached an example of the information for this product (Part # PRM10HFM). On page 33, there is a chart and i'm not sure which pressures/flow to add-do i add the psi for the discharge? or the inlet? I'd use the H=KQ^n +C. An help would be much appreciated.



Thanks,

Sam

[jovivier]

Hi Samantha,

Firstly some general tips about PRVs and IRRICAD:

- The downstream pressure for the PRV is entered when placed in the design.

- PRVs regulate the pressure when placed inline on pipes.

- Do not place PRVs in loops.

- PRVs are specified in the database in a particular way - enter PRV into the "Fitting Type" field in the database in the Other Hydrualics component group.

- The required information for the curve fitting is pressure loss vs. flow (when the PRV is not regulating which shows the friction loss through the item). The Pressure loss discharge is only used to ensure there is enough pressure to regulate.

- Pressure loss vs. flow is commonly depicted in a graph as seen below for a Bermad PRV:

PRVPressureLoss.png

- If you are able to obtain pressure loss information for the regulators you wish to use, as a check when calculating the constant and index with the curve fitting utility, the index for a valve or Misc.Hydraulic item should be in the vicinity of 2.

- Also see Help|Help Topics User Manual > Entering Information into IRRICAD > Using Misc Hydraulic Items.



Secondly in your particular situation the PRVs you wish to use have an approximate fixed downstream pressure. To model this in IRRICAD you will still need to enter the fixed pressure when placing the PRV on the design.

Tips are:

- Include the specific downstream pressure in the description to remind you what value to enter when using in a design.

- Because the downstream pressure is not 100% fixed you could use the flow limits (min and max) in the database to help keep you within ranges where the downstream pressure is 10psi (i.e. in this way you will receive messages when higher or lower flows are outside this range which therefore produce a different discharge pressure according to the product tables).

- If you cannot obtain pressure loss data you can make a guess at the pressure loss and enter this as the C value (leave the K and n as 0). This means that regardless of the flow the regulator will require at least the C value entered in order to regulate in your design (i.e., does not have a dynamic relationship). You may also wish to reduce the flow limits as above for the item so that your 'guess' is not used for higher flows where the unregulated friction loss may be greater.


Where are you planning to use these PRVs? Note that PRVs will only regulate when placed inline on pipes in the design. If the PRV is added as part of an assembly the assembly is not regulated unless it is a PRV assembly.

Regards,


Jo