Priority valve tune up

[Hoosier]

How to tune up (adjust) a flow rate on a priority valve?



The priority valve is being sold only with three main categories, pressure range, max. flow rate, and a thread size.


For example,

1/4" FPT Inlet x (2) 1/4" FPT Outlets
Flow Capacity: 2-50 SCFM, 5000 psi service



If I need to get 10 SCFM flow rate at 2,200 psi for my chamber, how can I adjust this off the shelf priority valve.


I guess a key component is a proper sized restrictor (orifice) though. There is a linear relationship between a set up pressure and flow rate, for example, 50 SCFM at 5,000 psi and 25 SCFM at 2,500 psi?




Any expertise?


Thanks in advance!

 

[Jimmer]

I could be totally off the mark here, but I thought pressure maintaining valve simply held a set pressure and didn't control flow rate at all. The way I would interpret that information, is that the valve can handle flow rates up to 50 cfm and can be adjusted to restrict pressure up to 5000psi.

 

[Waterskier1]

I could be totally off the mark here, but I thought pressure maintaining valve simply held a set pressure and didn't control flow rate at all. The way I would interpret that information, is that the valve can handle flow rates up to 50 cfm and can be adjusted to restrict pressure up to 5000psi.

I think Jimmer is correct. the flow capacity is spec'd so that if you remain in that range, the insertion loss (restriction) is negligble. Too low, and it may not maintain pressure reliably, too high a flow, and it will become restrictive. It's a pressure maintaining valve, not a flow regulator.

 

[cool_hardware52]

How to tune up (adjust) a flow rate on a priority valve?



The priority valve is being sold only with three main categories, pressure range, max. flow rate, and a thread size.


For example,

1/4" FPT Inlet x (2) 1/4" FPT Outlets
Flow Capacity: 2-50 SCFM, 5000 psi service



If I need to get 10 SCFM flow rate at 2,200 psi for my chamber, how can I adjust this off the shelf priority valve.


I guess a key component is a proper sized restrictor (orifice) though. There is a linear relationship between a set up pressure and flow rate, for example, 50 SCFM at 5,000 psi and 25 SCFM at 2,500 psi?




Any expertise?


Thanks in advance!

You cannot control the flow rate with a Priority Valve. The PV only controls the pressure the of the filters up stream of it.

Flow control is a more difficult thing. A fixed orifice will have a flow that varies with the pressure drop across it.

If you want to limit the flow through a filter bank you can use an orifice (or needle valve) at the outlet and set this orifice (or needle valve) to limit the CFM at or near the max pressure you expect to have in the system.

I have a bank of Hyperfilters that need to be limited to no more than 9 cfm. The problem is how to determine flow across an orifice with a 5000 psi differential.

Here's how I did it. With no filters cartridges installed I estimated the internal volume of my Hyperfilter towers, just measure the ID and internal length.

This will give you a volume. Calculate the volume of the filters at the pressure you will operate them at. That gives you a total cu ft for the tower(s)

Calculate the CF/ PSI. With the towers pumped up to pressure, and the compressor off, you can time how long it takes to drop XX psi through your needle valve. I used 400 psi, and started 200 psi above my target pressure, and timed how long it takes to drain to 200 psi below my target pressure. That way the average pressure drop across the orifice was pretty close to the 3200 psi target I was aiming for.

It is a "cut and try" process, but it works. Took me about 4 tries.

I also use a slow opening valve between my primary filters and the hyper filters. Remember if you put the orifice at the outlet of the hyperfilter it will not limit how fast the hyperfilters will initially charge with gas from the primary filters / compresor / or Grade E air banks if any. I did not want to hit my hyper filter carts with 100+ cfm.

Good luck,

Tobin

 

[pescador775]

Rather than feed us a bunch of unverifiable data why not just provide a source for the information? A priority valve is not a back pressure valve and how or why some dive equipment vendors came up with that name is unfathomable. What did you do, google up "priority valve" and get confused? I ask because what you have described sounds like a real priority valve and not a backpressure valve. What exactly are you trying to buy?

 

[cool_hardware52]

Rather than feed us a bunch of unverifiable data why not just provide a source for the information? A priority valve is not a back pressure valve and how or why some dive equipment vendors came up with that name is unfathomable. What did you do, google up "priority valve" and get confused? I ask because what you have described sounds like a real priority valve and not a backpressure valve. What exactly are you trying to buy?

Pescador,

Why the attitude? Has anybody participating in this thread said anything that justifies your response?

Look here http://www.aquaenvironment.com/om/0550_OM_211_020906R.pdf

"Model 211 Back Pressure Regulator"

"Also know as a Priority Valve......"

If Aquaenvironment finds it fit to refer to a back pressure regulator as a priority valve then there is a good chance that term is in the common vernacular.

One of the specifications of "Back Pressure Valves" is a range of CFM flows, i.e. 1-10 cfm, 2-50 etc. It's pretty easy to see how one might interpret this to mean the flow is adjustable.

You are a smart guy with a lot of compressor experience. Might I suggest a little Dale Carnegie training?

Tobin

 

[Hoosier]

You cannot control the flow rate with a Priority Valve. The PV only controls the pressure the of the filters up stream of it.

Flow control is a more difficult thing. A fixed orifice will have a flow that varies with the pressure drop across it.

If you want to limit the flow through a filter bank you can use an orifice (or needle valve) at the outlet and set this orifice (or needle valve) to limit the CFM at or near the max pressure you expect to have in the system.

I have a bank of Hyperfilters that need to be limited to no more than 9 cfm. The problem is how to determine flow across an orifice with a 5000 psi differential.

Here's how I did it. With no filters cartridges installed I estimated the internal volume of my Hyperfilter towers, just measure the ID and internal length.

This will give you a volume. Calculate the volume of the filters at the pressure you will operate them at. That gives you a total cu ft for the tower(s)

Calculate the CF/ PSI. With the towers pumped up to pressure, and the compressor off, you can time how long it takes to drop XX psi through your needle valve. I used 400 psi, and started 200 psi above my target pressure, and timed how long it takes to drain to 200 psi below my target pressure. That way the average pressure drop across the orifice was pretty close to the 3200 psi target I was aiming for.

It is a "cut and try" process, but it works. Took me about 4 tries.

I also use a slow opening valve between my primary filters and the hyper filters. Remember if you put the orifice at the outlet of the hyperfilter it will not limit how fast the hyperfilters will initially charge with gas from the primary filters / compresor / or Grade E air banks if any. I did not want to hit my hyper filter carts with 100+ cfm.

Good luck,

Tobin

I fully understand what priority valve is and its function. However, I was told that LF priority valves on the Hyper Filter Appliance has an orifice (restrictor) built in.


Tobin actually hit the nail on the head. You must be psychic, Tobin.
It is a good tip....

For the cascade system, it is a “must have” item for the Hyper Filter Appliance to secure an appropriate dwell time. In the same reason, for a direct compressor hook up, the compressor max. capacity should be lower than one on the appliance.

 

[cool_hardware52]

I fully understand what priority valve is and its function. However, I was told that LF priority valves on the Hyper Filter Appliance has an orifice (restrictor) built in.

True, LF includes a flow restricting orifice at the outlet of their Hyperfilters.

Tobin actually hit the nail on the head. You must be psychic, Tobin.
It is a good tip....

Not psychic, just been there, done that.

Tobin

 

[Waterskier1]

True, LF includes a flow restricting orifice at the outlet of their Hyperfilters.

Does this flow restricting orifice maintain pressure in the appliance after it is shut down? Is it adjustable? I would think the only way it would be "adjustable" is by replacing the orifice with another with a different size orifice which would allow a different preset flow, which really isn't "adjustable".

 

[cool_hardware52]

Does this flow restricting orifice maintain pressure in the appliance after it is shut down?

No, an orifice is just a hole, how could that maintain pressure? If you shut off the outlet and have a check valve on the inlet, and no leaks you can maintain pressure in the appliance.

Is it adjustable?

LF furnishes a fixed orifice that limits flow at a particular pressure drop across the orifice.

If you need an adjustable "orifice" you need a needle valve.

Tobin