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Centrifugal to change to PD PUMP

Centrifugal to change to PD PUMP

Centrifugal to change to PD PUMP

(OP)


Hi all,

As per my simple sketch, we want change Centrifugal PUMP with design shutoff 6 barg to PD air pump with design 45 barg, and this pump handling sulfuric acid . Few of issue i can see here. Need mitigation for that

1. Design pressure alot higher for downstream piping and equipment, is that can lower RV set pressure a per downstream piping design pressure
2. PD pump RV vent to pump suction, however it can backpresure to tank which is design at tank
3. PD pump flow rate is only 1 m3/hr compare Centrifugal pump 3 m3/hr
4. N2 pressure is 3 barg, is that can backpressure, need check valve
5. Any other concern with this design ?

RE: Centrifugal to change to PD PUMP

1. What is the design code for the downstream piping? What are the design P&T?

2. What do you mean a “PD air pump”? Is this an air-operated double diaphragm pump? Typical short-circuiting the pump pressure relief is NOT a good idea.

3. That’s your problem to solve.

4. I don’t even see where the N2 on your sketch is supposed to go. Is it going to the seal?

5. Yes. If the automatic valve is controlling based on flow, your PD pump may cause control issues if it has significant pulsations.

RE: Centrifugal to change to PD PUMP

(OP)
Hi,

Thank you for reply. Downstream piping design for 150 #. This Piston pump air operated but instead of air they want use N2. If not put RV, if a block outlet happen. It will overpressure the Piston pump right.

RE: Centrifugal to change to PD PUMP

Most air-operated pumps operate on a ratio basis (i.e. 1:1, 3:1, etc) where the output deadhead pressure is a ratio of the air supply pressure. You need to determine your pump’s ratio and your air supply pressure to determine the actual deadhead of the pump. The design pressure of the pump simply states the maximum pressure allowable on the pump - it doesn’t mean the pump will actually output that pressure in your installation.

To save on piping, you could put a regulator and then PSV on the air supply side to prevent the pump from ever being capable of running a deadhead pressure above your pipe design pressure.

Oh, also saying the flange class is 150# doesn’t help. 150 class flanges are NOT a design code. ASME B31.3, for example, is a design code. 150# flanges are not.

Also, piston pumps produce a lot of vibration.

RE: Centrifugal to change to PD PUMP

Modifications can be positive or negative depending on would they provide a desired result.
What is the purpose of the modification? What do you want to achieve?

RE: Centrifugal to change to PD PUMP

(OP)
The original pump out for repair, this just temp pump replacement

RE: Centrifugal to change to PD PUMP

Hi,
Going for trouble ! Check whether your truck is equipped or can be equipped with a pump ( call the supplier).
Maintenance seems weak at your place , need spare parts (preventive maintenance) .

If you go for PD , what is the back up plan for membrane rupture , outside the compatibility with Sulfuric acid ?
You also need to be able to manage the flow rate , N2 or air pressure must be equipped with a regulator .
Where are routed the fumes from the tank ? Scrubber or atmosphere ?

Good luck
Pierre


RE: Centrifugal to change to PD PUMP

We pressure off-load our muriatic acid. Talk to your acid supplier.

Good Luck,
Latexman

RE: Centrifugal to change to PD PUMP

Amanda,

I appreciate English may not be your first language, but there are some missing information here, especially about the type of pump you are planning to us. Can you post further details or a link or a photo as your information at the moment doesn't make a lot of sense.

Using Nitrogen as a motive power source sounds like a lot of expensive gas to me being used - why not air?

But this needs a proper MOC system BEFORE you actually do it, reviewed and approved by local experienced engineers.


1. Design pressure a lot higher for downstream piping and equipment, is that can lower RV set pressure a per downstream piping design pressure
Yes, you need to make sure that the downstream pressure does not exceed the design pressure of the piping system.

2. PD pump RV vent to pump suction, however it can backpresure to tank which is design at tank
No it can't because the inlet is the source of the liquid.

3. PD pump flow rate is only 1 m3/hr compare Centrifugal pump 3 m3/hr
Not much you can do about that other than use three pumps.

4. N2 pressure is 3 barg, is that can backpressure, need check valve
Don't understand the question. The nitrogen system is different to the product system. Where is this check valve on your diagram?

5. Any other concern with this design ?
Yes - you don't seem to have a lot of experience or supervision. You need to get this reviewed and checked by suitable personnel in your organisation.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Centrifugal to change to PD PUMP

(OP)
Hi Thanks for feedback

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