setting of hand reg valves

[ecclesk]

What is the correct proceedure for the setting of hand regulaing valves on evaporaors

one of the systems i look after has three evaps and all the hand reg valves are set to 4.5 turns (since commisioning 1987). I have always wondered how they are set up, i presume it must involve taking temps pressures etc and balancing the evaps acordingly.

i'm not having probems with the current settings i would just like to know how its done.

any advice would be greatly appreciated.

[chemi-cool]

Hu ecclesk,

What make are these valves?
It would make it easier to find info.

Chemi

[PobodysNerfect]

Habemus Papam!

If we are talking of hand regulating valves in pump system, then you should calculate how many turns the valve should be open.

Obviously, if you do not circulate enough refrigerant the evap do not function correctly, but, interestingly, neither will it function correctly if you circulate too much refrigerant.

In order to calculate the opening degree, you need some information from the manufacturer.

For instance, in case of Danfoss reg valves you need to know the cone size in the valve (a certain size of valve can be equipped with different cone sizes). Then, from Danfoss catalog or webpage, you can get information about how to calculate / select a reg valve, and also how many turns it should be open if you know the mass (or volume) of refrigerant you need to circulate and the pressure before and after the valve.

In short, you need to know the capacity and the circulation factor (normally 3-4) of the evap, and the pressure drop. Then you look op the characteristic of the valve and calculate the opening degree. Again, in case of Danfoss, you can also use their Dircal program.

Saludos,

Jan

[ecclesk]

it's a pump circulated system using R22, three evaps 96Kw each. Runs a coldstore at around -25.

liquid enters the valves at 4 bar, suction pressure is around 0.5 bar

the valves are Robinet RVDS 25.

[chemi-cool]

Hi ecclesk.
Never heard the name and so is google

I know the Danfoss 6F, manual expention valve,
used in flooded systems and ensures even supply of refrigerant to the evaporator.

you can get more information at : www.danfoss.com

Chemi

[ecclesk]

thanks for the advice chemi, i'll see what i can find out

[PobodysNerfect]

The web site is:

http://www.rff-france.com/

There is not much information, but you can ask for the information required.

j

[Peter_1]

These aren't manual expansion valves I think.
The purpose is to make sure that all evaporators have the same friction/resistance so that the flow is equal through all the evaporators.
They use the same principle in water circulating systems to be sure that all the different coils are fed correctly.
This is especially necessary when 3-way valves or 2-way are used and the valves are closing when the coils has reached the preset temperature. The whole systeme should come otherwise out of balance.
Franck knows the correct name for these valves, he gave it me once.
Some manufacturers have free circular slide rulers.
Click on Balancing valves on http://tacat.tourandersson.com/4/product_frame.htm and some more on http://www.flowdesign.com/