7 replies to this topic

[raj shekhar]

Hi all,

 

for a high viscosity fluid application, is it possible to install an air operated diaphragm pump at the suction of the lobe pump.

Considerations -

1. Lobe pump location can't be changed.

2. Tank can't be charged with high pressure.

3. With that lobe pump being fixed at a same location, pressure drop in that line is very much high, lobe pump may not be able to pump the liquid.

4. Lobe pump is connected with a hose, taking advantage of that if an AODD pump is placed the suction pressure drop can be halved, and AODD pump will give enough pressure at the lobe pump suction so that it doesn't starve.

5. Discharge pressure is high, AODD Pump will not be able to push the liquid to that far.

I am attaching the pump arrangement with this. Let me know your views.

 

Sketch link -

https://drive.google...iew?usp=sharing

Edited by raj shekhar, 08 June 2020 - 02:07 PM.

[thorium90]

What is this high viscosity fluid?

[raj shekhar]

What is this high viscosity fluid?

It's some kind of Hair gel.

[jayari]

Attachment not included.

[raj shekhar]

Attachment not included.

Sorry, I shared a link, using that you can see the schematic.

[thorium90]

What you are describing is a feeder for the pump.

This is a common method of feeding for high viscosity pumping applications such as the one you describe.

Attached a picture of the feeder that I got from Netzsch pump catalog.

The top picture is more suitable for you. The bottom one is for fluids that can form bridges such as pumping powdery or dry sludge cakes that has very high apparent viscosities.

An AODD may still not be able to meet the NPSH for the lobe pump.

You may also need to change the piping to have much more gentler bends so that the head loss in the suction does not exceed the NPSHr of the pump.

You can calculate the head loss with typical head loss formulas. The high viscosity will give you much higher head loss in your suction pipe, much higher than in low viscosity fluids like water, resulting in insufficient in NPSHa to your lobe pump.

If as you mentioned, the piping is actually all hoses, then I would suggest much larger diameter hoses to reduce the friction loss. PTFE lined hoses may be helpful too.

Attached Files

•  Lobe Pump Feeder.JPG   100.43KB   0 downloads

Edited by thorium90, 09 June 2020 - 06:51 AM.

[thorium90]

If the options above are not feasible due to the existing setup you have or some other restrictions, then I would suggest a more drastic option would be to not use that lobe pump and to change to using a flexible screw conveyor instead.

A link to a vendor webpage and a youtube video describing how it works is below.

 

https://www.flexicon.../Principle.html

 

https://www.youtube....h?v=jx71QjB9NlE

Edited by thorium90, 09 June 2020 - 07:02 AM.

[raj shekhar]

What you are describing is a feeder for the pump.

This is a common method of feeding for high viscosity pumping applications such as the one you describe.

Attached a picture of the feeder that I got from Netzsch pump catalog.

The top picture is more suitable for you. The bottom one is for fluids that can form bridges such as pumping powdery or dry sludge cakes that has very high apparent viscosities.

An AODD may still not be able to meet the NPSH for the lobe pump.

You may also need to change the piping to have much more gentler bends so that the head loss in the suction does not exceed the NPSHr of the pump.

You can calculate the head loss with typical head loss formulas. The high viscosity will give you much higher head loss in your suction pipe, much higher than in low viscosity fluids like water, resulting in insufficient in NPSHa to your lobe pump.

If as you mentioned, the piping is actually all hoses, then I would suggest much larger diameter hoses to reduce the friction loss. PTFE lined hoses may be helpful too.

Hi Thorium,

 

Thank you for your suggestions, very helpful.