Hydraulic diagram interpretation

[21121956]

Hello everybody:

In the diagram, at the entrance of the filters "A" the flow delivered by the pump is 105 liters/min. If we follow the branch up to the point 1, we can see that after the flow control valve, the available flow is 26,7 liters/min but, after the flow meter, that flow becomes 33,3 liters/min.

I wonder, where does that additional oil come from?

I would appreciate your comments. Thanks in advance.

El que no puede andar, se sienta.

 

[HPost]

There is no more oil. Just because there is reference to a higher oil flow rate, doesn't mean that more oil will be present. The 26.7 Ltrs/min is setting on the flow control valve, whereas the flow meter will measure the flow, possibly up to a maximum of 33.3 ltrs/min. There is a switch shown by the flow meters, the 33.3 ltrs/min could be the setting on that switch.

It could also be a typo. The system is certainly not generating oil.

Cheers

HPost
CEng MIMechE

 

[21121956]

Hello everybody:

Thank you very much HPost for your input. I beg your pardon but, I can not help but wonder, why it is indicated the setting of the control valve, 26,7 ltrs/min, if in the end what matters is that the flow meter gives the indication that through the branch 1, are passing 33,3 ltrs/min?

Any idea about this?

El que no puede andar, se sienta.

 

[MikeHalloran]

In some outfits, there would be a column in the bill of materials for each item, showing specific data such as maximum flow rating for the flowmeter, set point for the flow switch, and nominal setting for the flow control valve.

What you have provided appears to have been cut from a larger drawing. Perhaps there are notes or a table that explain what the numbers mean. There may even be a separate system calculation document that explains everything.

We can only conjecture what the numbers _might_ mean.



Mike Halloran
Pembroke Pines, FL, USA

 

[HPost]

It's important to note that this is just a drawing, it may not represent the actual way in which the system works.

It is pure conjecture at this stage as there could be many reasons why there is a difference. I would say however that the 26.7 ltrs per minute is the required setting of the flow control valve, while the 33.3 ltrs/min is the trip point on the flow meter that would/could trigger another event within the system.

It's only a best guess though...

what does the system actually do? Do you know that???

Regards

HPost
CEng MIMeche

 

[kcj]

Several possible interpretations:
-The flow controls could be a maximum limiting flow in that branch. 0-5-10-20 is normal, but 26.7 is the maximum wanted.
-None of the circuits operate together at 26.7, but maybe together at say 8 for the total of 33
-33 could be the maximum scale on the flow meter
-33 could be the normal reading on the meter

As others already say, the answers depend on larger context or what other tables or notes there are.

I know the ISO/NFPA schematic goal is all information conveyed via symbols and numbers, not language, but I always try to go beyond the bare minimum. More information is usually better. My preference if possible is, for each component, in a separate notes table, to list the known, fixed, characteristics of the part (in3/rev, bore, stroke, rpm, etc), the best possible output (33 lpm at 1750 rpm at 100% efficiency, maximum psi, 100-3000 adjustment range, maximum temperature, scale range, etc), the expected maximum output (30 lpm at 1750 rpm at 95% efficiency), and the expected operation steady state condition (5 lpm at 1500 psi)
This gives the technical info on the device, a maximum and a reasonable output for testing, and a 'normal' reading the operator should expect to see.

kcj

 

[kcj]

Oops, rereading, the 33 is after the flow control, not before.
Don't know, is it a maximum over limit condition? Same comments though, the overall context of informations somewhere else should clarify. If not,slap the drafter/engineer who drew the schematic.

k

 

[21121956]

Hello everybody:

Thanks to all of you for your invaluable comments. Here I am sending the complete hydraulic diagram.

El que no puede andar, se sienta.

 

[HPost]

It's still ambiguous. It seems that whoever drew the this schematic has just divided the total pump capacity by 4. 99.9 across 3 legs and remainder across the last.

Still can't see why the flow control valves show the lower figure though???

 

[21121956]

Hello everybody:

Now that we have the scheme available, I think is the moment to ask a couple of questions: when one of the pumps (15.2L or 15.1L) is in normal operation, what is going on with the fixed flow control valve (11L) and the check valves (10L and 8.3L)? What is the function of these devices?

Why in that return line has been installed that check valve 8.3L instead to permit the free flow of the returning oil to the sump tank?

Once again, thanks to everyone of you.

El que no puede andar, se sienta.

 

[LittleInch]

The fized control valve looks like an orifice of 1mm to me and is a fixed flow recycle line. Check valves are there to prevent backflow through the pump from the inlet lines to the mechanical pump. When the mechanical pump is going flat out in "normal" mode, it appears to supply all the oil that is required with the electric pump oil going via 22L back into the tank and seemingly being used as a back up to continually supply lube oil in all conditions, wheterh running or not

It's interesting that the total volume of oil going back to the tank via flows 5 and 6 totals 110 l/min and the oil in totals 105 l/min... Looks like no one did a proper check on this drawing (no Note 6 for instance)

You need to read an operating manual to find out things like what does switch 20L do? Turn on the electric pumps? alarm?, turn something off?

Heat to de disapted from the bearings normally - 40 KW???? what sort of machine is this? - Ditto "overspeed" - 90kW??

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[21121956]

Hello everybody:

Thanks LittleInch for your observations and comments.

This machine is a synchronous hydro generator which is coupled to a small Francis turbine.
As you suggest, it is required to ask for the operation manual in order to understand (interpret) the function of the equipments as a whole.

El que no puede andar, se sienta.