Is it possible to program this onto a Click PLC? If so, I need help anyway.

I assume it's double acting, there is no way it can be anything else. Nowhere on the site does it say this but we can assume it is because of the single piston inside. In the catalog on page 9 under key features it says that the drive pressure can be 3-100 psi so I assume that minimum 3psi from the I/P will still turn the pump. In that case the dump valve needs to be between the pump and the air regulator, correct? (A-E in my diagram) This valve will only be used when depressurizing I think, from my assumptions the pump will stop once the I/p reaches it's set psig value. When we want to depressurize, we energize the 3/2 dump valve which will cut off the main air supply to the pump and also release all air pressure from the pump, while at the same time we open the second dump valve for the water side right? After a couple seconds the system will be depressurized. Is there a specific way I should do this? Should I open both the water side and the air side at the same time, or do they have to be in certain order to not damage anything?

It also says for this pump on the catalog page there can be modifications on it, one of the modifications says "Allows user to regulate drive air to as low as 3 psi (.2 bar)". So I am not sure if the pump can or cannot cycle at 3psi. It says it can do 3psig on the key features but then in the modifications it says it allows 3psi air drive. So, I am not sure if my specific pump has this modification, not sure why its a modification if one of the key features of the pump is 3-100 psi drive pressure. Not I am not sure what to do, I guess test the pump out manually if it can cycle off 3psig air drive.

Edit: After thinking about it more and more there is no need for an air dump valve I think, if the air supply valve is closed and the pump is stopped there is still pressure between the pump and air supply valve. When we want to depressurize the system, we simply open the water side dump valve and the remaining air in between the pump and shutoff valve will be used and then spit out by the pump.

As the water side loses pressure can the pump still cycle or take in air? If this is the case then the dump valve is not needed and the problem I thought I had is gone.

Also @drbitboy in your program the step for starting the pump in subroutine 40 rung #1 says it says to get the HMI setpoint and divide it by 16, then this value is sent to the I/P. This is not starting the pump, right? Also we want to slowly increase the I/P pressure from the start point, not straight to the sp and then increase, I am not sure if the pump can handle an almost instant change in pressure. Would we also want a constant number for this as the start pressure will be the same for each test. Is there a rung I am missing hidden in another subroutine that starts the pump?

Aljubovic said:

I assume it's double acting, there is no way it can be anything else. Nowhere on the site does it say this but we can assume it is because of the single piston inside. In the catalog on page 9 under key features it says that the drive pressure can be 3-100 psi so I assume that minimum 3psi from the I/P will still turn the pump. In that case the dump valve needs to be between the pump and the air regulator, correct? (A-E in my diagram) This valve will only be used when depressurizing I think, from my assumptions the pump will stop once the I/p reaches it's set psig value. When we want to depressurize, we energize the 3/2 dump valve which will cut off the main air supply to the pump and also release all air pressure from the pump, while at the same time we open the second dump valve for the water side right? After a couple seconds the system will be depressurized. Is there a specific way I should do this? Should I open both the water side and the air side at the same time or do they have to be in certain order to not damage anything?

Click to expand...

I don't think the order matters.

I think the pump is single-acting. I just re-read page 7, and the 225cycle/minute limit is for continuous service. So maybe it's okay to run 475+ cycle/minute to get 428 cuin/minute for non-continuous service. That is quick though.

I will not use the dump valve. It's way simpler to just have one valve on the water side depressurize the whole system. The only thing I am worried about is if the pump can cycle 3psig. If it can then the pump will cycle the remaining air left when the water dump valve is opened. If not then nothing will happen. I am trying to think what is the best way to do this now. I can replace the air supply valve with the 3/2 valve that you mentioned, but this will add more steps inside the program since now we need to signal the 3/2 valve.
I will just use a basic 2 way solenoid valve for the air supply valve.

One question if I am using the 3/2 valve will the pump still keep pressure when this is energized? Once the setpoint is reached the air should be shutoff to the pump and a constant psi from the I/P will keep the pump stalled and at a constant pressure. If the 3/2 valve was used it would shut off the air and relief the remaining air in the pump, seems like this will make the system lose pressure if the air-driven pressure reaches 0.

Aljubovic said:

I will not use the dump valve. It's way simpler to just have one valve on the water side depressurize the whole system. The only thing I am worried about is if the pump can cycle 3psig. If it can then the pump will cycle the remaining air left when the water dump valve is opened. If not then nothing will happen. I am trying to think what is the best way to do this now. I can replace the air supply valve with the 3/2 valve that you mentioned, but this will add more steps inside the program since now we need to signal the 3/2 valve.
I will just use a basic 2 way solenoid valve for the air supply valve.

Click to expand...

1) It does not add anything to the program because that one discrete output, which is 1 when trying to pressurize and 0 otherwise, can probably be used for everything. Even if one output cannot drive two items, the internal discrete bit (C11), can trivially drive two or more outputs.

2) Also, if we use the 3/2 valve, then it could be argued that we do not need the valve upstream of the F.R.L., and we only need to control the 3/2 valve. So when the pressurization is done, the 3/2 valve does two things:

1. opens up, and depressurizes, the air volume from the 3/2 valve to the air inlet of the pump. Note that this will not affect the pump water discharge pressure (see below);
2. blocks off the air volume from the regulator output downstream to the 3/2 valve. While this does leaves air pressure in that section of line, it will not affect the pump until the next pressurization starts on the next test, when we will want to re-pressurize this volume anyway.

Aljubovic said:

One question if I am using the 3/2 valve will the pump still keep pressure when this is energized? Once the setpoint is reached the air should be shutoff to the pump and a constant psi from the I/P will keep the pump stalled and at a constant pressure. If the 3/2 valve was used it would shut off the air and relief the remaining air in the pump, seems like this will make the system lose pressure if the air-driven pressure reaches 0.

Click to expand...

The water discharge side of the pump has a ball check valve, which looks like this -<o- in the diagram. That is what will hold the pressure in the test part. If you leave the regulator pressure on the pump, then if the part and the ball check valve leak, the any pressure left in the air inlet side of the pump might compensate for that leak and so you would not detect a bad part or test apparatus.

It might even be worth putting a second ball check valve downstream of the pump water discharge, to minimize the probability that a leaky check valve is causing test failures on good parts.

Aljubovic said:

I will not use the dump valve. It's way simpler to just have one valve on the water side depressurize the whole system.

Click to expand...

That will not work, because one valve on the water side will not depressurize the whole system.

LOooking at your diagram I don't think it will work, for example when you fit a test hose we assume the whole thing will be filled with air at atmospheric, when you close the dump valve that air will be trapped in there, so adding water will increase the pressure but it will compress the air also, I suggest you re-think this, either move the water dump valve to the other end or have a second small valve to drain the air when water is added, so the scenario is add water with drain open to purge the air, close the valve once air is removed, bring up to pressure & so on.
If the test is with water I assume you will not want air in the system ?.
The only other thing if the dump valve is on top so air bleeds out but that would leave a slug of water after the test.

@parky @drbitboy Why not? I thought to relief pressure this is what needs to be done. Once the PLC is ready to relief pressure it will close the Pump Air Supply Valve and also close the fluid supply valve. Then simply all we do is open the fluid pressure relief valve and the pressure will be relieved in the pump.

This is how the operator does it manually. First closes the fluid supply valve, then the air supply valve, and then opens the fluid pressure relief valve.

Another thing to note, the fluid supply comes in at 80psig (I did not mark it on the diagram, so if pump is off and the fluid supply valve is open can connected to a test part, we can do minimum of 80psi tests) already so that's another thing I have to take into account when calculating how to get to the setpoint. Do I just minus 80psig from the hmi setpoint before converting it to the I/P transducer?

parky said:

LOooking at your diagram I don't think it will work, for example when you fit a test hose we assume the whole thing will be filled with air at atmospheric, when you close the dump valve that air will be trapped in there,

Click to expand...

Good point. For full automation the bleed valve should also be controlled by the PLC, which wpuld then also need a way to detect when water is coming out. Or could the bleed valve be a ball check valve where the ball falls due to gravity when air is passing at low pressure but floats and stops flow when water reaches it?

There is also the issue of anelastic strain. If the test duration is many minutes or even several hours, then the test part may "relax" against the stress (pressure), and expand its volume, which will result in a drop in pressure. With a bulk modulus for water of 3E5psi, that drop could be interpreted as a leak.

Aljubovic said:

@parky @drbitboy Why not?
...
Then simply all we do is open the fluid pressure relief valve and the [air] pressure will be relieved in the pump.

Click to expand...

Maybe.

The air pressure will be relieved through the pump. Any residual pressure on the air side will drive the air piston on its way to atmosphere, which will move a little water through the pump and out the water dump value.

By the same token, before the test is over, that residual pressure on the air side may add water to the test part, possibly masking a leak.

But that approach still requires an automated air valve between the FRL and the pump.

The 3/2 valve on the outlet of the regulator makes automating the air supply valve (on the inlet to the FRL) unnecessary. The operator opens that manual air supply valve at the start of the shift and closes it at the end. Only the 3/2 valve needs to be automated.

@ DR: thay's over complicating things just open the bleed valve for a time enough to expell the air no need for complicated things, even if it was left open for longer would not matter it is a simple way, arrange for the dump to be where air would be expelled, this would also serve as the dump at end of the cycle it's not NASA....

drbitboy said:

Maybe.

The air pressure will be relieved through the pump. Any residual pressure on the air side will drive the air piston on its way to atmosphere, which will move a little water through the pump and out the water dump value.

By the same token, before the test is over, that residual pressure on the air side may add water to the test part, possibly masking a leak.

But that approach still requires an automated air valve between the FRL and the pump.

The 3/2 valve on the outlet of the regulator makes automating the air supply valve (on the inlet to the FRL) unnecessary. The operator opens that manual air supply valve at the start of the shift and closes it at the end. Only the 3/2 valve needs to be automated.

Click to expand...

What if before we open the fluid pressure relief valve we open/close the 3/2 valve ( close or open forgot which one is the bypass) so that the air supply is stopped and then the air pressure in the line to the pump is reliefed. Therefore there will be no more residual pressure on the air side and won't cause water to go in the pump.

If the operator does this manually and has no problems I don't see why automating it would be a problem. If pressure got through the pump during this time then it would not do much since the fluid pressure relief valve is open.

parky said:

@ DR: thay's over complicating things just open the bleed valve for a time enough to expell the air no need for complicated things, even if it was left open for longer would not matter it is a simple way, arrange for the dump to be where air would be expelled, this would also serve as the dump at end of the cycle it's not NASA....

Click to expand...

I think this will only be used for the end of the test. Before I was going to close the air supply valve once the pump reached setpoint to not let the pump run anymore. I am pretty sure that this pump will not cycle at 3psig. I found another website that says minimum air drive is 25psig. So I think I will just keep the i/p at a constant pressure untill the end of the test, then the air supply valve will close along with the fluid supply valve. Then the fluid pressure relief valve will open.

Here is the website.

https://airlinemedia.airlinehyd.com/Literature/Manufacturer_Catalogs/Haskel/OM-16_E.pdf

On page 7 it says provide 25 psi minimum air pressure so I will have to start the pump at 25 psi and then pump slowly to sp.

Aljubovic said:

What if before we open the fluid pressure relief valve we open/close the 3/2 valve ( close or open forgot which one is the bypass) so that the air supply is stopped and then the air pressure in the line to the pump is reliefed. Therefore there will be no more residual pressure on the air side and won't cause water to go in the pump.

Click to expand...

Yes, that is the way to depressure the air inlet side of the pump.

Open/closed refers to the connection of the regulated pressure supply port 1(P) to the working outlet 2(A).

In our case the working outlet is the driving air going to the pump.

The valve in the image below in its Normally Closed position:

• "Closed" because the supply air 1(P) is blocked from 2(A), and
• "Normally" because the solenoid on the left is de-energized, so the spring on the right has pushed the block to the left, which blocks the supply air allows the working outlet (pump air) to vent to the exhaust 3(R).

And this next image is what it would look like in the Open state, with the solenoid energized, shifting the block to the right, compressing the spring, and air 1(P) from the regulator going to the pump air inlet 2(A):

I think you mis-read my post or perhaps I did not explain it, when I talk about bleed or dump I was refering to the water, forget about the air, once it is shut off by the air feed valve any residue air will disipate on probably a one cycle of the pump, a few psi left is no problem.
What I was actually going on about is your diagram shows the water dump valve halfway between the pump & the test piece, I think it should really go at the end of the test piece but that's just my opinion, because the test piece & the pipework to it will initially be full of air if you close the water dump valve then all you will do is compress the air with the water, as air compresses better than water you will end up with a bubble of air (quite large) in the test piece & pipework, assuming water should be test medium you need to purge the air out i.e. an extra step like so
10 Open Air to I/P, pump for x seconds (this removes the air from the test)

Step 20 Close Water dump valve (this then pressurises the system)
Step 30 & so on.
So lets make this clear as I can.
Fit test part.
Press start
Air solenoid feeding I/P opens & a signal (4-20ma) given to the pump (this will require enough to drive the pump).
The water enters the test, pushes air out of the test piece until water appears back in the water sump i.e. no more air in test piece.
Close the water dump valve.
Get to required test pressure.

Run the test.
Pass or fail.
Release water (dump valve to water sump)
& so on.