Piping Gurus

[BassBomb]

Hello,

I have a pipeline (2") which is at pressures between 0-50 psig

I have a sampling outlet which is approximately 1/4" in size

Is there a way to figure out how fast and powerful the stream would shoot out if the 1/4" outlet was opened? Can it be controlled or throttled? Can the flow rate be calculated?

The process fluid is pure ethanol (0.789 relative density)

 

[deadlyapp]

Q(flowrate)=A(area)*V(volume) If you use bernoulli's you can calculate flow based on some simple assumptions.

 

[calvinbiss]

Is there a way to figure out how fast and powerful the stream would shoot out if the 1/4" outlet was opened? Can it be controlled or throttled? Can the flow rate be calculated?

Yes, yes and yes.

 

[BassBomb]

v1^2 / 2 + gz1 + p1/density = v2^2 / 2 + gz2 + p2/density

I assumed v1 = 0, p2 = 0 (outside is at room pressure, assumed 0 gage), z1, z2 = 0 (assumed no gravity force)

p1 = 344 737.865 [kg / m s^2]
v2 = ? [m/s]
density = 789 [kg/m^3]

v2 = 29.56 m/s

q2 = v2 * A2

A2 = (pi) * (0.00635)^2

q2 = 0.00374 [m^3 / s]

OR

q2 = 3.74 [L/s]

Look right? I think my bad assumption here is the Z components are zero, this pipe is vertical and can drain out by gravity

We are talking a bunch of vertical pipe with a 1/4" opening at the bottom.... How does that change things?

z1 = 1.5 m

z2 = 0

v1^2 / 2 + gz1 + p1/density = v2^2 / 2 + gz2 + p2/density

v2 = 10.84 [m/s]

q2 = 0.00137 [m^3 / s]

q2 = 1.37 [L/s]


Why did including the height difference REDUCE my flow?

 

[Howard]

I'm pretty sure something like this is illegal.

 

[BurnItDwn]

I'm pretty sure something like this is illegal.

Are you thinking a still? Or maybe he's trying for home ethanol production (which I believe you can get a permit for?)

 

[Howard]

Are you thinking a still? Or maybe he's trying for home ethanol production (which I believe you can get a permit for?)

Not concerned about that, but from what I've seen, in industrial pure ethanol systems (e.g. non-denatured) you are not allowed easy access to the contents otherwise you can bypass taxation.

 

[CLite]

Why did including the height difference REDUCE my flow?

Height is going to have a minor effect compared to a 50 psig blow-down, it increases your velocity by about 1 m/s.

V2 = SQRT( 2(g*z1+P1/rho)) [be careful with units]

For a ¼” line you will want a simple quarter turn ball valve to drop the pressure down and thereby reduce the flowrate out of the header. This pressure drop occurs if you only partially open the ball valve. You don't want the pressure drop to be so great that the local pressure at the valve drops below vaporization pressure which will lead to cavitation problems. You can put a few quarter turn ball valves in series to slowly drop the pressure down to avoid cavitation problems if the system dynamics require it.

To properly design the sampling line you will need the Cv tables for the ball valves to determine the pressure drop versus flowrate, these can be obtained from the manufacturer. You will also probably want to buy Crane TP-410 so you can actually figure out what you are doing.

In terms of force, if the stream was to jet out the impingment force would be 2*a*(P) where a is the opening size and P is your gauge pressure of the system.

 

[Howard]

Height is going to have a minor effect compared to a 50 psig blow-down, it increases your velocity by about 1 m/s.

V2 = SQRT( 2(g*z1+P1/rho)) [be careful with units]

For a ¼” line you will want a simple quarter turn ball valve to drop the pressure down and thereby reduce the flowrate out of the header. This pressure drop occurs if you only partially open the ball valve. You don't want the pressure drop to be so great that the local pressure at the valve drops below vaporization pressure which will lead to cavitation problems. You can put a few quarter turn ball valves in series to slowly drop the pressure down to avoid cavitation problems if the system dynamics require it.

To properly design the sampling line you will need the Cv tables for the ball valves to determine the pressure drop versus flowrate, these can be obtained from the manufacturer. You will also probably want to buy Crane TP-410 so you can actually figure out what you are doing.

In terms of force, if the stream was to jet out the impingment force would be 2*a*(P) where a is the opening size and P is your gauge pressure of the system.

Easiest way to throttle the flow would be to put in a globe valve.

EDIT: The more I think about it, the more I am convinced you are trying to set up a frat party trick.

 

[BassBomb]

I'll take a picture of the actual application so you get the best idea possible...
What we are trying to avoid is basically an operator taking a sample of the solvent and getting sprayed or too much coming out at once.

The 1/4" sampling valve isn't really a normal valve. It is in fact A Keofitt 850005 with a manual (removable, but not spring return) handle
http://keofitt.dk/products/w9.html

Other issue is the handle could be left open and sample be constantly drained.

 

[BassBomb]

http://i.imgur.com/imsjS.jpg

Flow is from right to left, through filter and down to sampling valve TEE and final control valve.

Final control valve is NC and another valve upstream (not shown) will be NC during sampling. Therefore the line shown could be left at 50PSI pressure.


http://i.imgur.com/b8hrH.jpg

Valve port size (see the gap at fully open is small)

 

[Howard]

I'll take a picture of the actual application so you get the best idea possible...
What we are trying to avoid is basically an operator taking a sample of the solvent and getting sprayed or too much coming out at once.

The 1/4" sampling valve isn't really a normal valve. It is in fact A Keofitt 850005 with a manual (removable, but not spring return) handle
http://keofitt.dk/products/w9.html

Other issue is the handle could be left open and sample be constantly drained.

Well, a simple solution is to put a needle valve on the discharge. I see you have tri-clamp fittings, but alcohol plumbing typically doesn't need CIP cleaning since it isn't supposed to get contaminated, nor will any biofilms form.

As far as trying to prevent leaving the sample valve open, what's your budget? You could use the needle valve to "set" your desired sample flow, and then put a solenoid valve upstream controlled by a pushbutton with timer relay. A small plastic panel would work, probably cost you less than $500 total.

45585K85 on McMaster-Carr would do for the valve. Increase the tube size if your sample size is large.

 

[BassBomb]

Well, a simple solution is to put a needle valve on the discharge. I see you have tri-clamp fittings, but alcohol plumbing typically doesn't need CIP cleaning since it isn't supposed to get contaminated, nor will any biofilms form.

As far as trying to prevent leaving the sample valve open, what's your budget? You could use the needle valve to "set" your desired sample flow, and then put a solenoid valve upstream controlled by a pushbutton with timer relay. A small plastic panel would work, probably cost you less than $500 total.

45585K85 on McMaster-Carr would do for the valve. Increase the tube size if your sample size is large.

No CIP required they will simply spray the outlet with IPA before drawing a sample.

Purely mechanical solution is required... Solenoid, XP (Class 1 Div 2) rated and adding control schemes for this is out of the cards.

The needle valve, would you place it upstream or downstream of the sample valve?

 

[Howard]

No CIP required they will simply spray the outlet with IPA before drawing a sample.

Purely mechanical solution is required... Solenoid, XP (Class 1 Div 2) rated and adding control schemes for this is out of the cards.

The needle valve, would you place it upstream or downstream of the sample valve?

They do make XP solenoid valves, though I suppose adding any electrical would just be a huge pain in the ass. Don't know about there, but here every time we add a new electrical system we have to get the hazloc inspectors to certify it.

I would put the needle valve as the most-downstream item. Essentially the output of the needle valve is where you would collect your sample.

Let me brainstorm about the mechanical solution for timing. I don't suppose you trust your operators enough to shut the valve when finished?

EDIT: Here's what you can do. Put an NC air-actuated valve (5032T11 on McM-C) into the fluid stream and run air tubing to it THROUGH a spring-return manual air control valve (6464K19). What will happen is that the AA valve will open only when the SRMACV is actuated, and since the SRMACV automatically closes upon release, the AA valve will close. Presto, no electrical required, no wasted product (unless your parts break). BTW, if you do this, make sure you install the valve the right way if you choose to use an angle-seat valve; you might end up getting hammering if you do it wrong.

EDIT2: This thread would've been so much less confusing if you had shown us the application right away.

 

[BassBomb]

They do make XP solenoid valves, though I suppose adding any electrical would just be a huge pain in the ass. Don't know about there, but here every time we add a new electrical system we have to get the hazloc inspectors to certify it.

I would put the needle valve as the most-downstream item. Essentially the output of the needle valve is where you would collect your sample.

Let me brainstorm about the mechanical solution for timing. I don't suppose you trust your operators enough to shut the valve when finished?

Our process safety guys don't trust them enough

Right now im juggling the options on adding to this sampling valve, or buying a completely different and safer (closed) solution to sampling

 

[skyking]

I would not want to be "that guy" who is always mentioned in past tense.

 

[Howard]

Our process safety guys don't trust them enough

Right now im juggling the options on adding to this sampling valve, or buying a completely different and safer (closed) solution to sampling

If you route the sampling point to a "safe" location you can take fewer precautions. However, the longer the dead leg off your loop or header, the more flushing you need to do prior to a sampling.

 

[AstroManLuca]

I really thought this thread title was "pimping gurus"

 

[BassBomb]

Lets assume I don't have that sampling port as originally shown:

Lets say I replace it with two spring spring return ball valves in series

System under pressure between 0 to 50 psig

Open valve A, allow the liquid to flow in section A-B and fill completely (design this section to be a specific low volume, ie 50mL).

Close valve A.

Open valve B, draw a fixed volume sample.

If the pressure is very low, will this lock the system and no liquid will flow out?

Do I need some kind of air venting to allow air to enter the system for the sample to flow out?

 

[iGas]

Try using a needle valve to control the flow, other wise a ball valve/gas cock will do in a pinch.

If I'm correct. It sounded like the OP is looking for a vent or some kind of liquid/gas trap, ie. stream trap, gas/liquid separator.

 

[Howard]

You will always get some liquid into this valve trap but it depends on how well the air can be evacuated from it. If it cannot be fully evacuated then the volume of liquid will always vary and you will have a spurt coming out every time you open it (due to the air spring). Also, can your system deal with the ingress of air? I should say no, because the oxygen in it could combust.

Are you just trying to get a fixed sample size from the system without using any electricals?