Richard L

iTrader: (5)

This is very an interest aspect for the boost related PPS system. It looks the PPS system suit your application perfectly. I think it will also suit the positive displacement SC well on the surface.

The Centrifugal surcharge obeys the square law - boost is not strictly linear to RPM rise - hence it rarely see much boost at low RPM.

If we discussing the WAI flow matching the power curve, it will also need match the fuel demand. For this to work well, we have to take account of the specific fuel consumption of the set up. More fuel is needed to supply the added load imposed by the supercharger - If you base the WIA flow relative to boost and and not fuel flow, you need to make some adjustment on your fuel map to compensate the non-linearity between the two flows - fuel=3D and PPS=2D.

It will not going be a simple "bolt-on and go" affair - but pretty close.

Whoosh

iTrader: (19)

Each different type of medium that you flow through a specific type of conduit will record a different reading at the measured point. Viscosity of the medium and frictional factors of the specific material of the conduit will contribute to the variance in your collected data. Gasses, obviously, will not give you the same values as liquids, but for the test you propose, air would give a relative recordable value.
First of all it is not theory, the information I passed along is based on engineering constants. As to your question, yes if the pressure was equal on both sides of the check valve the spring would not open. But, that is not the case in an injection system. You have a constant pressure on the upstream side of the valve and when that meets or exceeds the spring value, naturally the valve opens. The difference is that you have an open orifice (the spray nozzle) that is very much open. Because of this, the pressure passes through the valve to the nozzle and into your device (or I/C pipe in our case). Petro/Chemical plants all over the world use similar set-ups for chemical injection in cooling towers, lube oil systems etc. The more critical the system the more sophisticated the pressure control device becomes.

Richard L

iTrader: (5)

If the pressure drop is small than 20psi, the valve should close by definition?

I am be able to explain why you think this is the case. If you have any open ended checkvalve, you will not see any pressure at all.

Mass flow generates pressure = keeps the valve open - agreed 100%.

But if you have a restriction downstream (water jet), the flow will no longer able to keep the valve open, 20psi differential remains true.

Whoosh

iTrader: (19)

No, because you have a constant upstream psi value.

cpoevo

iTrader: (1)

Let me clarify here. These numbers are just for explanation purposes. The checkvalve has a cracking pressure of 20 psi. So the pump will discharge 20 psi and open the valve. There will be a small pressure drop across the valve due to flow restrictions, lets say 1 psi. So the outlet side will have 19psi going to the nozzle. Now the nozzle creates a restriction which will create back pressure on the valve, but the pump discharge pressure will increase as well. Pump are rated at a certain psi and flowrate.

Every bend, valve, fitting, or anything else installed in the line will create pressure loss. The size of the hose or pipe will also effect the pressure of the pump. The loss usually will not be noticeable on a gauge though.

I understand basic fluid theory and know how to apply it, I just suck at explaining it.

SlowCar

iTrader: (4)

isnt this easy to prove if the checkvalve is a source of restriction...

constant pressure source - 125psig

A - pressure source/pump -> nozzle

B - pressure source/pump -> checkvalve -> nozzle

the difference in volume output of injectant will indicate if the CV is a source of restriction

A - B = 0, no restriction
A - B >0, there is restriction from checkvalve

or is this too simplified?

Richard L

iTrader: (5)

This is getting to become a good discussion. I think I'd better set up the simple test and than we can discuss the result.

It looks pretty 50/50 for the time being. I will do it with air first and if time permit, I set up with water with a 22psi checkvalve.

dubbleugly01

iTrader: (24)

why is it that everyone has to throw their pedigree around when a different opinion is posted?

I've only been in the chemical industry (chemical engineer) for 20 yrs, graduated in 87, so you have me on experience. Yes, I have a Crane manual right behind me, in my book case, haven't cracked it open for probably 10 yrs or so. Haven't needed to.

If you need an engineering type example..... say you have a boiler that makes 150# steam, and you let down 150# steam across a pressure regulator (pretty darn close to the ball/spring design Richard showed) to control another header at 50#, you're saying that regulator is only going to take a 1-4# drop? Last time I checked, that's 100#'s. The cross sectional area for flow will change based on flow demands, but the pressure drop across the regulator remains constant at 100#'s.

Richard L

iTrader: (5)

It is difficult to set this up with pump with pulses, even with damper etc. The checkvalve react with peak pressure rather average pressure. I normally test prototype with air than water. I will get myself with a pressure vessel so I can get pressurise water with little or no ripple.

Your test is simple and will get result. Didn't you once set something up similar a months or twos ago with a digital weighing machine. For I could remember, the test with two checkvalves flows less than one with one checkvalve. It will be interesting to do the same with no checkvalve at all and plot the three - three points are very useful.

Do you still have the link?

Richard L

iTrader: (5)

I have no experience in those industries. I just keep to simple logic, sometime I guessed right and sometime I guessed wrong. All we need is a simple set up I am about to do and if slowcar has the video clips, it also helps on the practical side.

If A(CV) - B(no CV)=0 than I will correct the text and apologise.

SlowCar

iTrader: (4)

i think the hosting site erased those files because they were huge.

i'll redo the 3 experiment today after work:

A - pump -> nozzle
B - pump -> checkvalve -> nozzle
C - pump -> checkvalve<->checkvalve -> nozzle

Pump = pulsing on-demand shurflo
Time for injectant collection = 60secs
Checkvalve = swagelok 25psig crack

dubbleugly01

iTrader: (24)

do you have the plot of flow vs. pressure for that nozzle? If so, you can get exactly what the dp is for the checkvalve.

SlowCar

iTrader: (4)

i'll be using Hago nozzle
http://www.hagonozzles.com/documents...M%20&%20MW.pdf

nozzle = M5

Whoosh

iTrader: (19)

In no way did I intend to belittle you or to throw around my "pedigree". If you are in engineering then you know that you must substantiate any statement or finding. The flaw in your thinking comes from trying to equate a regulator with a spring check. The regulator sole purpose, as you stated, is to reduce downstream pressure and hold it at a constant. A spring check serves two functions a) as a backflow preventer and b) to limit low pressure pulses from traveling downstream. Once opened (or cracked) the upstream pressure can rise to any set value and the resultant downstream pressure will be equal to that pressure minus the sum of pressure drop across the valve and line losses.
Richard, because I'm **** by nature and wanted to get a second opinion on your testing methods, I asked our Sr. Process Engineer what would be the most accurate testing device and set-up. Here is what we concluded:

Air as your medium would be acceptable (not totally accurate, but acceptable).
You will need a regulated air source. (compressor w/ regulator).
All connected piping should be hard piped for repeatability (any bends or kinks will change your readings).
Install one (1) pressure gauge upstream of the check.
Install a centrally located check valve with a known spring pressure.
Hard pipe to a spray nozzle installed in a larger diameter sealed tube (say 2-3 ft. long).
Install a pressure gauge in the end of the sealed tube.

To test, merely turn on your air source with a regulated starting pressure below the spring pressure. Open the regulator up untill you read 30# on the gauge in the sealed tube. At that point, read the pressure on the gauge in the upstream gauge. Subtract the downstream gauge from the one upstream and this will give you your pressure drop for the total system.

dubbleugly01

iTrader: (24)

the upstream and downstream pressure across a spring loaded ball check can never get closer than the spring rating, or else the ball will check. In this case, it's 20#'s. The pressure drop across the checkvalve can be more than 20#'s I agree, but never less, or the ball is gonna check! It's gonna open/close just enough to cause a 20# pressure drop until flow exceeds the systems capabilities to control at 20#'s, then it can be more.


No worries about belittling me, I love a good debate. I've been wrong before, I'm sure I'll be wrong some time soon again. Just not this time