Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here


Suction pressure of centrifugal compressor to be lowered

Suction pressure of centrifugal compressor to be lowered

Suction pressure of centrifugal compressor to be lowered

We have centrifugal compressor of 8.0barg suction pressure (15.0barg discharge pressure), we want to change its suction pressure to 5.0barg (New operating pressure), What are the guidlines to follow in order to know if it's possible or no? please give me help.

Many Thanks

RE: Suction pressure of centrifugal compressor to be lowered

Centrifugal compressors are fixed head, variable flow machines. Reducing suction pressure as much as 30% or more and increasing compression ratio from 1.8 to 2.7 does not look even theoretically possible.
Without knowing any other detail, I can advise to get in touch with the OEM (original equipment manufacturer) and seek their advice.

Process Engineer, MSChE

RE: Suction pressure of centrifugal compressor to be lowered

Hi EmmanuelTop

We are not going to change compression ratio, but theoretically what about flow, I mean, sizing : suction line, impellers of compressor and so on.

Many thanks for your replying

RE: Suction pressure of centrifugal compressor to be lowered


Not enough data, but clearly at lower pressure, your density decreases and hence overall flow capacity will almost certainly suffer as velocities inside the compressor increase.

However if compressor speed is variable / able to be changed, you might not suffer as much flow reduction as you would for a fixed speed unit, but max flow will reduce.

your compression ratio may well change as well for the worse.

on the other hand power decreases....

what are the guidelines? - Contact the vendor.

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

RE: Suction pressure of centrifugal compressor to be lowered

Why is your discharge 15barg? What can you do to lower it?

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

RE: Suction pressure of centrifugal compressor to be lowered

I think the guideline is to contact the OEM (or an upgrade specialist) and ask for feasibility study.

RE: Suction pressure of centrifugal compressor to be lowered

With regards to compression ratio - bear in mind that if you lower your discharge pressure the same as you inlet pressure - then you still change your compression ratio:

R1= 16/9=1.8 (have to use abs no.)
R2= 13/6=2.2

That may or may not be feasible but for a fixed speed compressor you should expect a serios reduction in capacity. Since you also have an increase in absolute flow rate (assuming that your mass/molar flow is kept constant this just makes it worse.

I gues that what you will have to do is to set up a simulation. Review the data with the compressor curve, feed the data to your manufactor and make them tell you if its possible. Perhaps some internal modification can make it fly.

Best regards, Morten

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login


eBook - Manufacturing the Cars of Tomorrow
In this ebook, we'll explore how additive manufacturing is going to transform the way cars are made. This includes commentary from thought leaders such as Ford's CTO, Ken Washington, Customer case studies of ways 3D printing is being used today, and a variety of part examples where 3D printing is already impacting how automobiles are made. Download Now
White Paper - Smart Manufacturing for Semiconductor
New technologies and approaches present great opportunities for semiconductor manufacturers to achieve high levels of innovation, yield and improvement. This white paper explores some of these cutting-edge technologies and how they can be applied effectively in the semiconductor industry. Read about how Smart Manufacturing is transforming the semiconductor industry. Download Now
White Paper - Analysis and Simulation in Aircraft Structure Certification
Organizations using simulation and analysis tools effectively see the benefits in their ability to achieve certification faster and with drastically less total cost than those who do not maximize these tools. Read this White Paper to learn about how digital tools such as analysis and simulation help in aircraft structure certification. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close